The Project Gutenberg eBook of Glimpses into plant-life
This eBook is for the use of anyone anywhere in the United States and
most other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg License included with this eBook or online
at www.gutenberg.org. If you are not located in the United States,
you will have to check the laws of the country where you are located
before using this eBook.
Title: Glimpses into plant-life
An easy guide to the study of botany
Author: Mrs. Brightwen
Illustrator: Theobald Carreras
Release date: July 9, 2026 [eBook #79061]
Language: English
Original publication: London: T. Fisher Unwin, 1897
Other information and formats: www.gutenberg.org/ebooks/79061
Credits: Mairi, Jack Janssen and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)
*** START OF THE PROJECT GUTENBERG EBOOK GLIMPSES INTO PLANT-LIFE ***
_GLIMPSES INTO PLANT-LIFE_
_BY THE SAME AUTHOR._
=WILD NATURE WON BY KINDNESS.= Illustrated. Seventh and Revised
Edition. Crown 8vo, cloth, 5s.
“We have no space to draw particular attention to the multitude of good
things to be found in this cheerful and unaffected little book, from
every page of which there breathes a sincerity which is necessary to
the enjoyment of such stories as these.”—_Saturday Review._
“The book is one which may be warmly recommended for the simplicity
with which it is written and the power of observation which it
displays.”—_Athenæum._
=MORE ABOUT WILD NATURE.= With Illustrations by the Author. Third
Edition. Crown 8vo, cloth, 5s.
“No better book can be given to juvenile naturalists.”—_Graphic._
“When this delightful book, full of observation, of tenderness, and of
humour, has been read, it becomes a friend, to be visited often and
cherished much.”—_World._
=INMATES OF MY HOUSE AND GARDEN.= Illustrated by +Theo. Carreras+.
Crown 8vo, cloth, 3s. 6d.
“This is a charming book, and prettily illustrated.”—_Spectator._
“A charming series of sketches.”—_Times._
LONDON: T. FISHER UNWIN.
[Illustration: NEPENTHES RAFFLESIANA.]
GLIMPSES
INTO PLANT-LIFE
_AN EASY GUIDE TO THE STUDY
OF BOTANY_
BY
MRS. BRIGHTWEN, F.E.S.
_Author of “Wild Nature Won by Kindness,” &c._
WITH ILLUSTRATIONS BY THE AUTHOR AND
THEO. CARRERAS
London
T. FISHER UNWIN
PATERNOSTER SQUARE
1897
[_All rights reserved._]
To
SIR JOSEPH DALTON HOOKER,
K.C.S.I., P.P.R.S., D.C.L., LL.D., ETC.,
_Formerly Director of the Royal Gardens, Kew_.
+Dear Sir Joseph Hooker+,—
In conversation with you I have often been impressed by your conviction
of the importance of inducing young people to observe the elementary
facts of botany, and I have heard you express your admiration of the
efforts made in this direction, in an earlier generation, by that
distinguished botanist, Prof. Henslow. You have assured me of your
sense of the value of independent observations made by young students,
for themselves, in the simplest and clearest language.
By your own example the studies of beginners have often been led in
this direction, but in this little book, which I have ventured to
produce, and of which you have kindly accepted the dedication, I have
not attempted to compete with even your least ambitious flights.
All I have endeavoured to do is to prepare the minds of young people
for the study of botany by explaining in the simplest language some of
the elementary phenomena of plant-life. It is an humble experiment, but
made, as I believe, on lines which are novel so far as they go, and
essentially practical.
If, as is too likely to be the case, I have fallen into any technical
errors, your good nature must not be held responsible for my fault.
Believe me to be,
Yours very sincerely,
ELIZA BRIGHTWEN.
_April, 1897._
⁂ _The greater portion of this work has
appeared in serial form in “The
Girl’s Own Paper.”_
PREFACE
When I was a young girl I can well remember how much I longed for some
simple book that would help me to learn, not merely the name of a
plant and what class and order it belonged to, but something about its
life-history.
It seemed very wonderful that, if I put seeds into the ground, dry and
dead as they looked, I might feel sure young plants would presently
come up; that, if I planted an acorn, a young oak-tree would in due
time be seen; but how all this came to pass I could not discover. I
had access to an excellent library, but although I searched there hour
after hour, and found many a learned book about plants, they might
as well have been written in Sanskrit for all I could understand of
their scientific pages. There seemed nothing suited to the mind of
a thoughtful child, and although, since that long-ago time, endless
books have been written for young readers and thinkers, delightful
books, too, which meet the needs of those who desire information and
instruction, I have not hitherto met with one that makes the careful
study of plant-life really interesting and practicable for those young
people who may not have a teacher to help them in their study.
It has been my aim in the little volume I now venture to send forth to
my young friends, known and unknown, to supply this deficiency. I want
to enable them to share the joy of spending hours in a garden learning
to understand the structure of plants. I want to make them able, when
they see a bud, or a root, or a twig, to know what the history of that
object is, how it comes to have the shape it takes, how it developed
into its present condition, and what its next form will be.
The possession of the simple facts which I have tried to make plain to
every intelligence in the following pages will turn a country walk
from a useless lounge into a lively object-lesson, delightful, from
beginning to end, alike to teacher and taught. Nor will I apologise
for the simple language which I have used, for my design has been,
while taking advantage of all the latest discoveries of science, to
use no terms and introduce no ideas which cannot be made intelligible
to a thoughtful child. In the hope that even so humble an effort as
this may not be without a use in enlarging and quickening a sense of
that infinite harmony which runs through every part of the Creator’s
marvellous plan of nature, I put forth, not without a full sense of its
inadequacy, this little volume. It has, at any rate, given me an excuse
for endless hours of pleasure within the precincts of my own woods and
garden.
I have to acknowledge great indebtedness to Mr. J. W. Odell, F.R.H.S.,
whose wide knowledge of botanical science has been of essential service
in ensuring, as far as possible, the accuracy of my statements.
ELIZA BRIGHTWEN.
CONTENTS
CHAPTER I.
PAGE
+Adaptation+ 25
Plant collections—General view of vegetable growth—
Lowest forms of plant life—Water buttercup—Vallisneria—
Water-lily—Mare’s-tail—Sea-weeds—Cacti—Orchids—Tillandsia—Seed
dispersion.
CHAPTER II.
+Roots+ 47
Root fibres—Hygroscopic water—Root hairs—The evil
of stagnant water—Binding roots—Carex arenaria—Psamma
arenaria—Cheddar cliffs—Correlation of roots—Land, water, and
air roots—Laurel root in well—Horizontal stems—Poa bulbosa—
Earth-nut—Potato—Onion—Air roots—Hoya—Aëroids—Parasitic
roots—Yellow rattle—Clover dodder—Flax dodder—Mistletoe—Root-
cap—Office of the root—Growing mustard-seed—Strength of roots.
CHAPTER III.
+Tree Stems+ 73
Expansion of bark—Shedding bark—Repairing injury—Epidermis—
Fibro-vascular bundles.
CHAPTER IV.
+Leaves+ 97
A leaf a digestive organ—Petiole and blade venation—
Monocotyledons—Dicotyledons—Radical leaves—Phyllotaxis—
Epidermis—Stomata—Influence of foliage upon climate—Eucalyptus—
Mesophyll—Chlorophyllon—Pallisade tissue—Protoplasm—Absorption
of carbon-dioxide—Jewel-weed—Alchemilla—Growing wheat—Vertical
leaves of eucalyptus cork layer—Fall of the leaf—Useful
products of trees.
CHAPTER V.
+Buds+ 123
Buds formed in summer—Hollow stalks of plane-tree—Terminal
and axillary buds—Spiral arrangement—Pollard willow—Suckers—
Dormant buds—Bulbils on lily stem—Protection from cold—Leaf
and flower buds—Folding of embryo leaves and flowers.
CHAPTER VI.
+Flowers+ 149
Floral envelopes—Buttercup—Gamopetalous—Polypetalous—
Epipetalous—Apocarpous—Woodsorrel—Syncarpous pistil—Geranium-
coloured bracts—Composite flowers—Fading flowers—Flower
expansion—Flower dissection—Cruciferous plants—Papilionaceous
flowers—Honey glands—Entomophilous flowers—Catkins—Monœcious
and diœcious flowers—Arum—Protection from insects and moisture.
CHAPTER VII.
+Pollination+ 175
Cross pollination in dog’s mercury and hazel—Pin-eyed
primrose—Maiden pink—Wind pollination—Araucaria—Pollination
by moths—Nottingham catchfly—Attraction of scent—Bartsia—St.
John’s wort—Japanese toad-lily—Pollination by humming-birds.
CHAPTER VIII.
+Fertilisation+ 193
Pollen grains—Micropyle—Nucellus—Embryo-sac—Experiment with
lily pollen—Changes after fertilisation—Growth of embryo—
Albumen—Arillus in spindle-tree—Yew and nutmeg—Persistent
style of clematis—Ovules—Changes in ovary of oak and datura.
CHAPTER IX.
+Fruit+ 209
Wide meaning of the word fruit—Diversity in appearance and
character of various fruits—Dehiscent and indehiscent
pericarp—Epicarp—Chestnut involucre—Mesocarp and endocarp—
Pericarp—Achene—Strawberry an apocarpous fruit—Pineapple—
Irritating hairs—Resinous protection of cones—Coiled stem
of cyclamen—Seed-pod of ivy-leaved toad-flax hidden in wall
crevices.
CHAPTER X.
+Dispersion of Fruits and Seeds+ 227
Dispersion by hooks and spines—Martynia—Testa—Di Quaglia—
Burdock—Bedstraw—Dispersion by winged seeds or achenes—
Sycamore, pinus tribe, birch—Dispersion by silky down or
hairs—Dandelion, goat’s-beard, groundsel—Willow-herb—Bird
agency—Seas and rivers—Dispersion by elastic force—Pansy—
Balsam—Furze—Broom—Squirting cucumber—Dispersion by
hygrometric sensitiveness—Barley—Feather-grass—Mexican
insect—Dispersion by sticky glands—Linnæa Borealis—Salvia
glutinosa—Plumbago—Ground-nut self-buried.
CHAPTER XI.
+Germination+ 249
Testa and its various forms—Collomia—Axis, tigellum,
hypocotyle—Centre of growth—Double embryo—Three conditions
required for germination—Varying time in different plants—
Cedar of Lebanon—Railway-bank flora—Broad beans—Cress seed—
Tillandsia—Collecting seedling trees—Fern and moss spores—
Prothallium—Archegonium—Antheridium germ cells—Capsular fruit
of mosses—Protonema.
CHAPTER XII.
+Physiology of Plants+ 273
Processes of plant growth—Nutrition—Water and gas as plant
food—Water culture—Osmosis—Experiment showing absorption—
Nitrates—Insectivorous plants able to absorb nitrogen to some
extent—Second experiment on absorption—Preparation of plant
food—Water bouquet—Transpiration—Use of Stomates—Respiration—
Seeds give off carbon-dioxide—Effect of light, darkness, and
heat—Reproduction—Protococcus—Strawberry runner—Asexual and
sexual reproduction—Effect of cold upon seeds.
CHAPTER XIII.
+Insectivorous Plants+ 295
Special purpose of each plant organ—Various modes by which
plants entrap insects—Sundew—Venus fly-trap—Trapping insects
by sticky hairs—By viscid glands—By pitchers containing
fluid—Sarracenias—Roridula—Utricularia—Nepenthes—Pinguicula.
CHAPTER XIV.
+Habit of Growth in Plants+ 313
Tropical forest—Perching orchids not parasites—Mistletoe—
Yellow rattle—Saprophytes—Murderer fig-tree—Mutualism—Corn
blue-bottle—Clover and bacteria—Symbiosis in white poplar
and fungus—Sea anemone and algæ—Bryony tendril—Mycetozoa.
+Glossary+ 335
LIST OF ILLUSTRATIONS
+NEPENTHES RAFFLESIANA+ _Frontispiece_
PAGE
+WATER BUTTERCUP+ 36
+VALLISNERIA+ 37
+CATTLEYA WALKERIANA+ (_A Brazilian Orchid_) 41
+YOUNG SCOTCH FIR GROWING IN HOUSE-LEEK+ 44
+CREEPING GRASS+ 56
+POA BULBOSA+ 57
+LILY BULBILS+ 60
+CLOVER DODDER+ 64
+SECTION OF ROOT CAP+ 68
+TURKEY OAK BARK+ 76
+SCOTCH FIR BARK+ 77
+SNAKE-BARK MAPLE+ 78
+TURKEY OAK STEM+ (_struck by lightning_) 79
+PLANE TREE BARK+ 80
+HORSE-CHESTNUT BARK+ 81
+WHITE POPLAR BARK+ 82
+SYCAMORE BARK+ 83
+TREE-FERN BARK+ 84
+STEM OF YELLOW WATER-LILY+ 87
+STEM OF WHITE WATER-LILY+ 87
+GROUP OF BEECH-TREES WITH INTERLACING STEMS
AND ROOTS+ 93
+CONVOLVULUS+ 94
+NETTED VEINS+ 100
+MONOCOTYLEDON+ 101
+DICOTYLEDON+ 102
+TAMARIND SEEDLING+ 103
+STOMATA+ 107
+LEAF SECTION+ 109
+YOUNG SHOOT OF EUCALYPTUS+ 116
+MATURE FORM OF EUCALYPTUS LEAVES+ 117
+OAK IN WINTER+ 127
+OAK IN SUMMER+ 129
+HORSE-CHESTNUT+ 135
+YOUNG BEECH+ 138
+UNFOLDING ARUM LEAF+ 140
+UNFOLDING LEAVES OF HART’S-TONGUE FERN+ 140
+PEAR LEAF+ 140
+BUDS OF WAYFARING TREE+ 145
+PRIMROSE+ 153
+POINSETTIA+ 157
+WINTER CHERRY+ 160
+WALLFLOWER+ 162
+SWEET-PEA+ 165
+BIRCH FRUIT+ 168
+WILD ARUM+ 170
+PRIMROSE+ 179
+MAIDEN PINK+ 181
+ARISTOLOCHIA+ 186
+STAPELIA+ 188
+HYPERICUM+ 189
+TOAD-LILY+ 191
+POLLEN-GRAINS+ 196
+WHITE-LILY PISTIL. SECTION OF PISTIL+ 197
+POLLEN TUBE+ 198
+SECTION OF COCOA-NUT+ 203
+SPINDLE-TREE+ 204
+NUTMEG AND MACE+ 205
+CLEMATIS OR TRAVELLERS’ JOY+ 206
+SECTION OF PEACH+ 216
+POPPY CAPSULE+ 217
+WOODY PEAR+ 218
+PINE-CONES+ 223
+SEED-POD OF MARTYNIA+ 230
+BIRCH SEED+ 232
+PARACHUTE+ 234
+DANDELION SEED+ 235
+GOAT’S-BEARD+ 236
+COCOS-DE-MER+ 238
+BROOM AND SWEET-PEA PODS+ 242
+STIPA PINNATA (FEATHER GRASS)+ 244
+BIGNONIA SEED+ 252
+DOUBLE EMBRYO OF ORANGE+ 255
+BROAD BEANS+ 258
+GROWING MUSTARD SEEDS+ 261
+BEECH COTYLEDONS+ 264
+ACORN+ 266
+HORSE-CHESTNUT+ 267
+YOUNG DATE-PALM+ 269
+TRANSFUSION DIAGRAM+ 278
+SKELETON LEAF+ 284
+SUNDEW+ 300
+VENUS FLY-TRAP+ 304
+SARRACENIA FLAVA+ 306
+BLADDERWORT+ 308
+PITCHER OF NEPENTHES RAFFLESIANA+ 309
+BUTTERWORT+ 311
+PERCHING ORCHID+ 317
+RAFFLESIA ARNOLDII+ 320
+GIANT COW-PARSNIP+ (_Heracleum Giganteum_) 325
+CORN BLUE-BOTTLE+ 326
+BRYONY TENDRIL+ 331
+TRICHIA THROWING OUT SPORES+ 332
“To me be Nature’s volume broad display’d,
And to peruse its all-instructing page;
Or, haply catching inspiration thence
Some easy passage raptur’d to translate,
My sole delight.”
+Thomson.+
CHAPTER I
_ADAPTATION_
“My heart is awed within me, when I think
Of the great miracle that still goes on
In silence round me—the perpetual work
Of Thy creation, finished, yet renewed
For ever. Written on Thy works, I read
The lesson of Thine own eternity.”
+Bryant.+
CHAPTER I
ADAPTATION
The study of plants appears to me to be one of the most delightful and
instructive that can be taken up by young people. It has this advantage
over many other pursuits that it can be carried on almost everywhere,
for, even if the student’s lot is to live in a town, there are
generally botanic gardens within reach, and visits paid in the country
are made the more enjoyable when some special study can be carried on
in the daily walks.
Then collections of dried leaves and flowers can be formed during the
summer, and the arrangement and classification of these will provide
pleasant winter occupation.
I fear that many young people are apt to consider botany a very dry
study. They are naturally repelled by the long words and many technical
terms used in describing plants.
It has long been my belief that the study of botany should be
approached through the garden rather than the schoolroom, beginning
with a country ramble which should be an object-lesson opening out
endless paths for future study.
Our Heavenly Father has given us a beautiful world to live in, and,
when our eyes have once been opened to observe what lies around us,
nature becomes like an exquisite book of pictures, always revealing to
us something new and wonderful as we turn over each fresh page.
It is suited to all ages; the baby child begins by gathering daisies
and buttercups, while older children make wild-flower collections and
perhaps work in their own little gardens watching the growth of seeds
and slips.
The beauty of ferns and mosses is sure to lead to some painstaking
study of those fascinating growths.
Later on the fact that all trees have flowers comes as a surprise to
the unobservant, and thus, when rightly guided, young people can hardly
fail to love a pursuit that promises such endless sources of interest.
In the chapters that will follow on the subject of plant life, I do
not purpose to write for quite young children, as my hope is that
older readers will explain what is written, and make it interesting to
the little ones as they walk in gardens and fields, giving as it were
object-lessons on buds, leaves, and flowers, and training young minds
to search for themselves into the wonders that lie around them.
How much there is to learn about, even in the simplest things, some of
the succeeding chapters will endeavour to show, for example:
How young plants grow out of seeds;
How those seeds are dispersed;
How much is folded up in a bud;
How flowers are formed;
How the bark splits off different trees.
Any one of these subjects would need very careful, patient observation
truly to understand it.
I stand as it were only on the threshold of scientific research, and
look with wonder at the work of such a student as Darwin, who gave
twenty long years to observation of the common earth-worm before he
wrote his deeply interesting book upon it. Again, we see Sir John
Lubbock giving years of his life to the growing of seeds and their
seed leaves, in order to learn exactly how plants begin their life,
and two very thick volumes are required to contain the vast amount of
information he has thus obtained.
These two examples will suffice to show that the minutest objects in
nature are worthy of reverent attention, and if these chapters tend to
awaken young people to a perception of this fact and act as a humble
guide to new lines of thought, I shall feel that they have not been
written in vain.
I fear it is impossible to explain the processes nature is carrying on
in the plant-world without occasionally using scientific words, but,
when I am obliged to do so I shall try to explain their meaning,[1],
and when once we rightly understand an exact expression we soon begin
to use it, because it is more convenient and often saves repeating a
long sentence.
[1] See glossary at the end of the book.
I would ask my readers to try and obtain from their gardens and fields
the various objects mentioned at the close of each chapter, and
compare them with the plates, learning all about them as they read the
letterpress.
This will, I feel sure, add much interest to the study, for having
something to collect and examine tends to lighten mental work and
enables us better to understand descriptive writing.
In this introductory chapter I will simply take a general view of
vegetable growth and its adaptation to the situation in which it is
found.
In many respects plants require the same conditions as animals, birds,
and insects; they must have air, food, moisture and light in order to
attain healthy growth, and although they differ from animals in being
usually stationary, their life is carried on in a very similar way. Let
us take a forest tree as a type.
It is anchored in the soil by its roots which are its feeding organs;
through them it draws up various kinds of nourishment from the earth
in which it stands.
The roots by several chemical processes render the elements they have
taken up from the soil fit for the nourishment of the tree; they send
it up through the stem and branches into the leaves, and these being
the breathing organs have essential work to do in receiving from the
air, and giving out again, certain gases which contribute largely to
maintain the life and vigour of the tree. Thus it grows year by year,
producing annually its flowers and seed, which is the end and aim of
all plant life.
We can trace another analogy with animal life, in the necessity for
pure sweet air, plants growing in a vitiated or smoke-laden atmosphere
soon showing unmistakable signs of weakness. The stunted hedges and
trees on the fringe of London always remind me of the poor, ill-grown
children of the slums.
Besides the plant life which we see around us in the shape of trees,
shrubs, and flowers, there are lower and perhaps still more wonderful
forms of vegetable life affording endless fields of study.
Mosses, lichens, and fungi we are familiar with everywhere in the
country, but below these again are such growths as the green stain[2]
which makes the tree trunks in moist places as brilliant in colour
as the leaves themselves. Looked at through a lens we see the colour
arises from a growing plant of extremely simple form, little more in
fact than a succession of cells, each living and increasing “after its
kind.”
[2] _Protococcus._
Again, if we consider the process of fermentation, we find that when it
is set up in a cask of wine its action is due to the growth of a minute
vegetable that feeds upon the alcohol and sugar, and by robbing the
wine of those two elements turns it into vinegar or acetic acid.
A somewhat similar growth causes the thick jelly-like substance we
sometimes find in our inkglass when it has been allowed to remain too
long without renewal; the minute germs floating in the air have found
the ink suitable to them, and thus their mycelium[3] begins to form at
the bottom of the glass, to the great discomfort of the writer.
[3] First form of fungoid growth.
The yeast with which our bread is fermented is another of these minute
plants, and consists of oval cells which multiply with great rapidity
when placed in a pan of flour, and kept in a warm atmosphere.
By the careful study of these lower forms of vegetable life, Pasteur,
Koch, Frankland, and others have discovered and classified the germs or
microbes,[4] as they are called, which give rise to various diseases.
In books upon the subject, their different shapes are figured as they
appear when immensely magnified, so that we can see that which will
give rise to consumption, erysipelas, or cholera, and one reads with
deep wonderment of all that science has ascertained of late years as
to the presence in the air of these seeds of disease which are ever
floating more or less around us. But for the restraining hand of God,
it appears as if universal sickness and death would be our fate.
[4] Small living atoms.
Leaving these lower forms of growth, we may consider the three
divisions into which plants are naturally classed as to their duration
of life.
Annuals are those which grow and flower, and form their seeds in one
year, within which their life-history is closed.
Biennials produce leaves only in the first year; by their aid they lay
up stores of nutriment in the form of tuberous roots, on this food they
can exist through the winter, produce flowers the following summer,
perfect their seeds, and then die.
To this class we owe such useful plants as the carrot, parsnip,
beetroot, and many others which afford us such nourishing vegetable
diet.
Perennial plants live on for an indefinite number of years, flowering
annually, in some cases dying down to the root in autumn, and producing
fresh foliage the following year.
Water plants seldom have a fixed root, but remain floating, borne up
and kept in position by the water, their roots being the means by
which, in conjunction with the leaves, they derive nourishment from air
and water. It is well worth while to observe the two forms of leaves
in the water buttercup. Those on the surface are three-lobed, flat,
and round, they absorb from the air such gases as the plant requires;
while the leaves beneath the surface are divided into threads so as
to offer no obstruction to the flow of water and enable the plant to
collect needful food from the water. It can vary the form of its leaves
according to its requirements, since in running streams it may often be
found with the hair-like leaves only.
[Illustration: WATER BUTTERCUP.]
On the other hand, if its seeds are sown in moist earth, the seedlings
will grow and develop those flat leaves only which are characteristic
of land plants. This water buttercup, therefore, gives us a wonderful
example of adaptation to surrounding influences.
[Illustration: VALLISNERIA.]
Adaptation is remarkably shown in the Vallisneria, a grass-like
water-plant, found in Southern Europe;[5] it grows in freshwater lakes,
rooted in the mud, and yet its flowers need to be fertilised in the
air. In order to effect this, the small male flowers detach themselves
from their stems, and, rising through the water, float about upon its
surface. The female flowers are borne on a stalk, spirally twisted, so
that it can uncoil and allow the flower to reach the top of the water
whether it be deep or shallow. There the two kinds of flowers meet, the
seeds are formed and the stem coils up again and brings the capsule
below the surface, where it gradually matures.
[5] It can generally be met with at naturalists’ shops where aquaria
are sold.
The water-lily can grow a long or short stem as the depth of the water
may require to enable its leaves to lie flat upon the surface. I have
gathered lily flowers in my lake with stems from four to five feet
long, where the plant happened to be growing in deep water.
In such plants as the mare’s-tail (_Hippuris vulgaris_), we find the
stem specially adapted to a submerged life. Growing out of mud at
the bottom of a stream the plant upholds its slender stalks by two
different methods. Inside the epidermis (or outer skin) a strand of
rather tough tissue running through the centre gives flexible support,
whilst the rest of the space is filled up with very large air cells,
which give such buoyancy to the stems that even if they are three feet
in length they are kept upright in the water, rising ten or twelve
inches above the surface. It is a valuable as well as a curious plant,
as it has the property of absorbing the gases emitted by stagnant
water, and tends thus to purify the air.
The same power of adaptation is to be found in sea-weeds. Those growing
on rocky shores having short fronds covered with fructification, while
out at sea, ribbons of oar-weed may be found many yards in length,
formed, like the gulf-weed, of tough texture to bear the friction of
waves and storms.
If we were travelling in a Mexican desert, we should find those
remarkable plants which can be so well studied in the cactus-house at
Kew Gardens. Bearing in mind that for many months the plant must do
without a drop of rain, or in fact without moisture of any kind, it has
been necessary that the leaf-surface should be reduced to prevent loss
of moisture by evaporation, and so spines take the place of leaves, and
the stems are encased in a thick leathery skin, which protects the
plant from the burning heat of the sun. Very little moisture escapes
through this thick green epidermis; therefore when rain falls the
plants receive and store up their liquid food, and live sparingly upon
it during the long periods of drought, which last for three-quarters
of the year. Some of these cacti, as we see them at Kew, are tall,
straight-stemmed plants, others low-growing rounded masses, little
spiny cushions, almost like vegetable hedgehogs.
In the arid prairies of Texas, advantage is taken of the watery stores
of the cactus, for when other supplies fail, its fleshy stems are cut
open, and horses and cows greedily devour the succulent food, which
answers the purpose of drink, as well as affording nutritious fodder.
Our British spurge-plants have green leaves, a thin epidermis, and all
the ordinary characters of the plants of a temperate region, but by
comparing them with the spurges found in Madeira, we see how climate
causes adaptation to differing conditions. One of these spurges growing
in my greenhouse has a tall column-like stem, no leaves, and a thick
leathery skin, which would enable it to bear a hot, dry climate. It
thus mimics the giant cacti of Mexico.
[Illustration: +CATTLEYA WALKERIANA+ (_a Brazilian Orchid_).]
We may trace another contrast in our common groundsel and the large
succulent groundsels of the Cape and the Canary Isles, with their thick
fleshy leaves, the difference in form and texture being simply an
expression of the wonderful modification due to climate.
The lovely tribe of orchids make the same provision for long periods of
drought. Many of the species live in countries where the rainy season
lasts about six months, and is succeeded by as many months of dryness
and heat.
The air-plants we obtain from these countries have large pseudo-bulbs,
that is, the stems are enlarged so as to be storehouses of nutriment
upon which the plant exists, and by means of which it brings out the
gorgeous flowers which make Brazilian forests such fairylands of
beauty; every tree-branch being laden with parasitic orchids, their
lovely blossoms lasting month after month without the aid of rain or
dew, because Nature has provided each plant with its special store of
food, and has thus adapted it to the position it is created to adorn.
Another of these perching-plants is _Tillandsia Usneoides_, known in
Florida as Spanish moss, and often called “old man’s beard.” It hangs
from the tree-branches in tufts, like grey hair, and grows in such
profusion that it is collected and used for stuffing cushions. This
curious plant has no roots, but simply hangs from the branches, and
lives like the orchids by absorbing water from the moist air in the
humid forests where it is found.
The absorption by the long, hanging, grey roots of the orchids in one
case, and by the finely-divided leaves and stems in the other, are both
instances of the wonderful way in which Nature “adapts” the parts of a
plant to its requirements.
It often happens that seeds, blown hither and thither by the wind,
chance to fall upon places which are quite unsuitable to their mode
of growth; then we have an opportunity of seeing how their power of
adaptation enables them to triumph over almost insuperable difficulties.
I have observed a tiny plant of groundsel growing out of a chink in
a wall where there was scarcely any soil from which it could derive
nourishment, contriving to live on, however, and make the best of its
hard lot. Its stem, which should have been a foot high, could only
attain about two inches, and instead of dozens of leaves it had but
four, and yet it survived and even produced two small flowers, thus
touchingly displaying its power of adaptation.
[Illustration: YOUNG SCOTCH FIR GROWING IN HOUSE-LEEK.]
Another more remarkable instance which occurs to me was that of a
seedling Scotch fir, which had rooted itself in a lump of house-leek
on the top of a garden wall. For eight years the young tree managed to
live and grow, until it became a symmetrical well-branched fir-tree,
almost twelve inches high. By a supreme effort it produced a crop of
miniature cones, and soon after it died from drought and starvation,
the wonder being that it could have lived so long upon the modicum
of food the barren wall supplied, besides having to endure at times
periods of scorching heat as well as drought. The chief interest in
this example is centred in the fact that as soon as fruit-bearing has
been attained, then, and not till then, the little tree died, showing
how persistently under all hindrances and difficulties a plant will
endeavour to carry out the purpose of its creation.
We have seen in these instances some striking examples of the way in
which plant-life is adapted to its surroundings. Our examples have
been such as are easy of attainment, and such as we can verify with
our own eyes; but even more wonderful are the adaptations hidden away
in the recesses of the plant, and as we progress in our study these
arrangements of cells and tissues will be revealed to us. In order
however to see them, and to understand their true significance, we must
proceed step by step to study the parts of an ordinary plant; because
it is only by first mastering all we can of one part of a plant, and
then comparing that part with other plants, that we can hope to gain
real knowledge. Accordingly in our next chapter we shall take the root
as our starting-point, and ascertain its functions and uses, and the
part it has to play in the economy of the plant.
Specimens to be obtained:—Green stain on treebark (_Protococcus_);
yeast; annual, biennial, and perennial plants; water buttercup leaves;
vallisneria; water-lily stems; mare’s-tail plant; cacti; spurge;
orchids; tillandsia; plants growing in wall crevices.
CHAPTER II
_ROOTS_
“While thus through all the stages thou hast push’d
Of treeship—first a seedling, hid in grass;
Then twig; then sapling; and, as century roll’d
Slow after century, a giant bulk
Of girth enormous, with moss-cushion’d root
Upheaved above the soil.”
+Cowper.+
CHAPTER II
ROOTS
Let us begin our study of roots by considering the way in which plants
obtain their nourishment from the earth, and are kept in an upright
position by means of their root-fibres. These being out of sight, we
may easily not be familiar with this part of the economy of plant life,
but we shall soon see what important duties the roots have to fulfil,
and how much they vary in character and appearance according to the
soil, the climate, and the work they are required to do. The greater
number of annual plants (those which live only one year) have fibrous
roots, and of these we can find examples almost everywhere. A piece of
groundsel or tuft of grass will answer our purpose. On pulling it out
of the ground we see a bunch of whitish threads or fibres springing
from the crown of the plant (which is the junction between the stem and
the root), and on these slender fibres are hairs which are really the
active part of the root, for it is only through these hairs that the
rootlets are able to absorb the liquid from the soil, the fibres simply
acting as channels to convey the watery nourishment to the stem and
leaves.
Common earth consists of small particles of mineral substances such as
flint, chalk, or iron, and also of such vegetable matter as decayed
leaves and rotten wood.
The spaces between the particles are more or less filled with air, each
mineral particle being enveloped with a film of water. However dry
the soil may appear, this will always be found to be the case. It may
be tested by weighing in an agate balance some dry soil on a summer’s
day. There is a very delicate instrument called a hygroscope, which can
tell us when there is the slightest amount of moisture in the air, and
a clever German writer, Von Sachs,[6] has termed this film of water,
which gathers round earth-particles, hygroscopic water. It has been
ascertained by careful experiment that it is only on this delicate
watery film that the root-hairs of plants are able to feed. As these
hairs drain away the hygroscopic film it is always being renewed by the
free water which comes from rain and dew. The free water of the soil is
constantly passing from the surface to the subsoil, and by this action
plant-food, in the form of soluble earth salts, is presented to the
roots. The passage of the water is of the highest service to the roots,
since the warm air follows the water through the soil, and helps to
oxidise the mineral particles; these are thus rendered soluble, and are
taken up by the fine films of water, and so indirectly the roots are
fed. If, however, there is no outlet for the water and the soil becomes
water-logged this beneficial action is retarded, and to land-roots the
water is hurtful.
[6] Author of “Vegetable Physiology.”
We can now understand why stagnant water in the ground is so injurious
to plant-life, as it prevents the needful air from coming into contact
with the roots, and this is the reason why farmers are careful to
remove the surplus water from their fields by thorough drainage and
ploughing. Roots adapt themselves very wonderfully to their situation.
This piece of grass, which we are examining, if it grew in sandy soil,
would have its root-fibres covered with a downy growth to enable them
the more readily to absorb every particle of moisture in the sand.
Dr. Bonar speaks of the date-palm as having this same characteristic.
“These palm roots are peculiarly fitted to obtain every drop of water
that the sand contains; they consist of long fleshy strings or ropes,
shooting straight down into the sand, in numbers quite beyond our
reckoning, and extending over a large circle.”
The tendency of fibrous roots to bind sand together is taken advantage
of on many of our sea-coasts, where the sand blows inland and renders
acres of ground sterile and useless. There, if the _Carex arenaria_
(a kind of sedge) is planted, its roots will spread far and wide,
interlacing and creeping through the sandy soil, until in time the
latter becomes solid and no longer drifts inland.
An allied species of grass, _Psamma arenaria_ (or marrem grass) grows
abundantly at Bournemouth, and wishing to ascertain how far one of its
underground stems extended, with some amount of patience I disinterred
about six or seven feet of it in a bank on the sea-shore where it was
accessible. As it seemed to have no end, I could not ascertain its
entire length.
Another instance of root growth adapting itself to situations occurs to
me. In visiting the Cheddar Cliffs in Somersetshire I was struck by the
beauty of a plant which grew here and there out of the crevices of the
rocks. Its tufts of vivid green leaves looked so healthy and vigorous I
could not help wondering how it could obtain moisture enough to produce
such foliage, placed as it was high up on the dry face of a rock.
Failing to reach its roots in any other way, I climbed up to a spot
where I could remove some of the horizontal layers of stone. At last I
lifted a flat piece of rock just above one of those plants, and there I
saw at a glance the secret of its vigorous growth:
The roots had spread out over the surface of the stone for a distance
of eight or nine inches in a perfectly flat layer of fine fibrous
rootlets no thicker than a sheet of paper; these would doubtless suck
up abundant moisture whenever the rain beat upon the rocks, and there,
pressed closely between the two layers of stone the plant has its
water-supply stored up, and is enabled to look fresh and green when
other vegetation is suffering from drought.
In plant-life there is a marvellous variety in root-structure. Roots
differ much, not only in form, but in texture and duration of life, so
that to gain a true knowledge of them we must carefully examine those
of herbs, shrubs, and trees, and observation will soon teach us the
fact that there exists a close correlation between the form and texture
of the root and the size and character of the plant. The external
shape will depend principally upon whether a tap-root is developed
or no. Such, for instance, as the carrot and the dock are those of
the true tap-root character. Of branching roots we may find endless
modifications amongst ordinary field or garden flowers from the fibrous
roots of the little groundsel to the large fleshy tubers of the dahlia.
Between these two types there are others of an intermediate kind, but
it is possible to recognise amongst common plants the roots belonging
to one or other of the types I have described. For the purposes of
study we may broadly group roots into classes according to their method
of collecting and absorbing food. Thus we find one group growing in
soil and feeding upon the soluble earth salts and moisture of the soil.
Another group will be found growing in water, like the water-lily and
pond weeds. A third group simply hangs down in space from some perching
plant like the tropical orchid, whilst a fourth and very small group
consists of parasitic roots, of which a very common example is the
mistletoe. We will now study each of these groups separately.
I have already spoken of some kinds of fibrous roots, and may add that
if the root of a land plant is immersed in water, it will after a time
develop a different kind of fibre, capable of receiving nourishment
from water instead of earth. I remember seeing an instance of this in
the case of a laurel bush which grew near a well in our garden. We had
occasion to examine the water, and found that the laurel had thrown
down its roots below the surface, where they grew luxuriantly, finely
subdivided, of a delicate ivory white, owing to the absence of light,
and more than a yard in length. They had adapted themselves to the duty
of absorbing water only, but had we replanted them in earth they would
have withered, from their unfitness to take up the hygroscopic water of
which I have already spoken. On the other hand, if the seeds of a plant
formed to live in the water, such, for instance, as the water-lily, are
sown in ordinary soil, they adapt themselves to the new conditions,
and are able to live on the hygroscopic water they find around the
particles of earth.
[Illustration: CREEPING GRASS.]
Some plants send out a horizontal stem (culm) along the ground, with
a bud and some roots growing out of it at regular intervals. Each of
these joints (or nodes) takes root and forms a separate plant. What
are called strawberry runners are stems of this kind, and so are the
creeping stems of _Potentilla reptans_.
[Illustration: POA BULBOSA.]
I once found a plant of the latter growing on a low wall, and, as I
imagine, because it desired to reach the ground and root itself there,
it had thrown down a stem a yard and a half long with eight young
plants growing upon it at intervals ready to form so many colonies
when they should reach the ground.
One may frequently find stems of various grasses running along the
ground, and taking root at each joint. I have one such spray in my
herbarium, with twelve young plants upon it at regular intervals.
Some plants store up nourishment in their roots, as may be seen in one
of our common seaside grasses (_Poa bulbosa_); this soon withers after
flowering, and becoming uprooted, its bulbs, which are like small round
cheeses strung together, may be seen blowing about in the wind.
With such a provision as this, the parent plant is able to bear
extremes of cold and drought.
It is well for us that plants have this power of storing up their food
underground, for to it we owe such useful tubers as the potato and
Jerusalem artichoke.
One of our native plants, the earth-nut (_Bunium flexuosum_), has a
single round tuber which is eatable when roasted, and is often dug up
by children. Long ago, when England was liable to famines, even this
small tuber was valued as a means of eking out the labourer’s daily
meal. It is worth while to examine the curious divided tubers of some
of our common orchises, such as the spotted orchis (_O. maculata_), or
the meadow orchis (_O. morio_). The tuber which produces the leaves and
flowers withers away at the end of the summer, but it leaves behind it
a second tuber in which is stored up the nourishment required to enable
it to bring forth leaves and flowers in the following spring.
Tubers are in reality underground stems which have thickened into
rounded balls to contain plant food.
[Illustration: LILY BULBILS.]
If we examine a potato we shall see that it contains true buds in the
little hollows on its surface; these are called “eyes,” and each of
them if sown in the ground will produce a new potato plant. If a potato
is left in a damp cellar, each of these eyes will send out a stem, thus
proving that the “eye” has the nature of a bud. If we cut the potato in
half we shall see it is of an even substance mainly composed of starch,
but if we halve an onion it will be found to consist of rings or
layers of a thick fleshy nature, which proves it to be a bulb and not
a tuber. The onion is like a large bud growing underground, instead
of on a tree branch. We can prove how similar the onion and the bud
are, by searching on a lily stem for buds or bulbils, which are often
produced in the axils of the leaves; if we plant such a bud it will
throw out fibres and become a bulbous-rooted plant. Some of our native
grasses seem to have a singular power of adapting themselves to their
position. For instance, the common Timothy grass (_Phleum pratense_),
which usually lives by means of a fibrous root, can, if needful,
produce a bulb which enables it to keep living in a very dry place, but
if removed to a wet soil it returns to a fibrous root. Other grasses
have been observed to alter their root-growth in the same way, adapting
themselves to their surroundings.
+Air Roots.+
These absorb the watery vapour of the air; they cannot adapt themselves
to live in earth, but under certain conditions they can put forth other
kinds of roots that are partially adapted for growing in soil.
I may here give some personal observations about a certain _Hoya_ plant
that came into my possession so long ago as 1855. This muchenduring
plant lived in a hanging basket for many years, in the dry air of a
sitting-room. Its leaves were sometimes shrivelled from lack of water,
and it never had vigour enough to produce flowers. At last, after
enduring this life for twenty years, it was placed in a stove-house
where the moist heat suited its requirements. Then it flowered
charmingly, and even now is showing a further degree of enterprise
by growing a bunch of fibrous roots at the end of one of its stems. I
imagine it intends to plant itself into another pot standing near. I
am watching it with much curiosity, because if it does this, the old
plant will prove that it has a high degree of intelligence, and that
although it remained quiescent for so many years, it was only from lack
of opportunity to do more than quietly endure its privations.
In tropical countries, some plants and trees such as _Monstera_ and
_Philodendron_ send down slender aerial roots called lianes, many
hundred feet in length.
In the Aëroid House at Kew, I remember seeing these lianes coming down
from the roof of the house in search of water and earthy nourishment.
It seemed like actual intelligence that directed these roots to a tank
of water twenty-five feet distant from their starting-point above.
Whilst we are considering this subject, I may mention the curious root
action of a kind of fig-tree growing in the tropics which is sometimes
known by the name of the “Murderer.” Its seed often falls, or is
dropped by birds, amongst the leaves in the head of a palm-tree, there
it begins to grow and forms root after root, gradually descending the
stem of the tree and clasping it so tightly that at last the palm is
strangled and falls to the ground carrying its destroyer with it, where
it roots and grows into a tree.
+Parasitic Roots.+
As in human society there are thievish characters who live by preying
upon their neighbours, so in vegetable society we find quite a number
of different plants growing at the expense of others, inserting their
roots into the stems and roots of trees instead of drawing their
nourishment from the ground. Careful distinction must be drawn between
such plants as ivy, virginian creeper, clematis, lichens, &c., which
simply grow and climb on the bark of trees, and the true parasites
which are nourished by the juices of the trees and plants into which
their routs penetrate.
[Illustration: CLOVER DODDER.]
Some plants are only partially parasitic, such as the cow-wheat
(_Melampyrum_) and the yellow rattle (_Rhinanthus_). These represent
a very deceitful kind of growth. To all appearance the plants are
getting an honest living, the leaves are perfectly green and capable of
performing all the duties of leaves, and yet, if we remove a little of
the soil the plant will be found to be attached to, and growing from
the roots of some strong kind of grass, and is deriving its nourishment
from the food collected by those grass roots.
Yellow rattle grows abundantly in undrained marshy fields, where it
is easy to obtain the plant, so as to examine its mode of growth. We
may then go on to a clover-field and seek for that true parasite and
most troublesome enemy to the farmer, the clover-dodder (_Cuscuta
trifolii_). Its seeds are frequently mixed with the clover, and when
sown they germinate on the surface, but the little thread-like stem,
instead of entering the ground, feels about in the air until it reaches
a young clover-plant. It soon clasps its victim with its fast-growing
stem; as the clover grows the dodder coils around it and is carried
away from the ground.
As the wiry stem gains strength, it developes a series of suckers that
eat into the clover stem and rob it of the food it has collected; it
lives, flowers, and grows at the other’s expense. The rate of growth
of the dodder exceeds that of the clover, so that the latter is both
exhausted and choked by its snake-like enemy.
I once sowed a patch of flax in a garden, and not knowing that it too
had a parasitic enemy, I was greatly puzzled to find quantities of
pinkish threads growing out of the flax stems. These threads bore round
bunches of tiny flowers. All this was very pretty and interesting, but
it resulted in my patch of flax becoming a mass of interlacing threads
and dying a miserable death, fairly strangled by the flax dodder.
Another species of _Cuscuta epilinum_, grows on furze and also on
heather, it having the twine-like stems by which dodder may readily be
known.
We are all familiar with the mistletoe, its leathery leaves and its
white berries.
This plant grows out of the branches of poplar, hawthorn, and apple,
and very occasionally upon the oak.
In France and Belgium the custom of bordering the fields with single
rows of Lombardy poplars seems to favour the growth of mistletoe, for
its large green bunches form quite a feature in the landscape, and
cannot fail to be observed by the traveller as he journeys in the
railway train. I have been told that mistletoe is sufficiently abundant
to be used in Normandy as cattle-food.
If a mistletoe-berry is gently pressed upon a young branch of an
apple-tree, its own viscid juice will cause it to adhere, and before
long it germinates and sends its roots into the tissues of the tree; as
it grows, it fuses with them, and derives all its root nourishment from
the substances in the branch. Of course the tree is weakened by this
parasite, the sucking roots of which disturb the flow of the sap; woody
knots are apt to form, and not unfrequently the branch is killed by the
intruder which has fastened upon it.
Having touched upon the four principal kinds of roots, we will now take
a single root-fibre and examine it more closely. It seems scarcely
possible that such a brittle, feeble thread should be able to penetrate
into the ground and make its way amongst stones and sharp-edged
fragments of earth without being bruised or torn. The chief friction
is borne by the growing-point, and this always has for its protection
a root-cap; the section of the growing-point of root-fibre given in
the plate shows the outer skin, called the epidermis, and over that
is the root-cap shaped like a thimble formed of small cells. As they
are worn away outside and become dead tissue, owing to friction with
the soil, the cells are constantly being renewed from within. The root
is thus enabled to grow and perform its part in maintaining the life
of the plant. The presence of this root-cap and the absence of leaves
are the marks by which a true root is known and distinguished from an
underground stem. With a small lens one can see this extinguisher-like
cap protecting the extreme point of the root, and it is well to examine
a variety of specimens, and see how they differ slightly in size and
shape.
[Illustration: SECTION OF ROOT CAP.]
The one especial office of the root is to absorb liquid nourishment
from the soil for the benefit of the plant, and, as I have already
explained, this is done mainly through the hairs which grow upon the
fibres of the roots. For instance, there is no absorption in old
tree-roots, such as we sometimes see above the ground, nor in carrots,
turnips, and parsnips, but thrown out from such bulbous plants are
the fibres and their hairs which enable them to grow to maturity. We
may naturally inquire how the solid materials in the soil, which are
needful to the growth of the stem and leaves, can possibly be taken up
by these extremely minute hairs.
We may look upon the earth as being a sort of storehouse of
indigestible, unprepared plant-food which must be altered in its
character before it will be fit for absorption by the roots. Some
substances, such as sugar, will readily dissolve in water; others,
such as starch and sand, are insoluble, but the effect of rain-water
and atmospheric air passing through the soil, converts this insoluble
dormant food into soluble active food.
The root-hairs convey this food to the small fibres, and through them
as channels it passes on to larger ones, until it reaches the stem and
goes to feed the growing leaves and flowers.
In order to remain in a healthy state, roots must absorb oxygen gas,
and for this reason gardeners, when they find the soil growing caked
and hard on the surface, dig and rake the flower-borders in order that
air may freely permeate the soil and find access to the roots of the
plants.
Roots appear to be endowed with certain remarkable attributes, about
which learned books have been written of late, giving the result of
patient investigation as to their power of movement, the way in which
they are affected by gravitation, the influence of light, and other
forces.
The experiments of Darwin and other scientists have revealed very
singular facts about the movements of plants. The term used to describe
their motion is one we must learn, as it frequently appears in
botanical works. Circumnutation we may translate as wavering around,
and it well describes the curious way in which rootlets, for instance,
are always moving slowly from one side to the other, describing a kind
of oval zig-zag track through the earth. The fibres appear to have
a discriminating power, enabling them to choose convenient crevices
through which to penetrate hard soil, to avoid stone, and to seek out
any attractive food which lies in their way.
As soon as roots emerge from the seed they at once turn from the
light and seek to bury themselves in the earth; the plumule from
which the leaves will spring has exactly the reverse tendency, and
invariably seeks the light and grows upwards. This can be proved by
growing some mustard seeds on a piece of flannel about the size of a
shilling, floating it on water in a saucer exposed to light from a
single window; as soon as the leaves appear, they will lean towards the
light, whilst the roots will point towards the dark part of the room.
If a germinating seed is even placed with the root uppermost, and the
plumule pointing downwards, it will very speedily right itself, the
stem will turn and grow up, and the root will seek the ground.
The amazing strength of growing tree roots can be imagined when we
watch a tree in full leaf during a high wind. As the terrific force of
the gale sways the trunk backwards and forwards the roots are subjected
to an enormous strain. Like great india-rubber cables they give and
retract, and when the wind subsides we find the trunk as rigid as ever.
If my readers will seek for the specimens enumerated below, and compare
them with the remarks made in this chapter, they will have such a
general idea of the functions of roots as will, I trust, enable them
to enjoy the study of more advanced works upon the subject.
Specimens to be obtained and compared with the descriptions in this
chapter:—Sedge or marrem grass growing on a sandy sea coast; plants
growing between layers of stone; tree roots at the edge of a pond;
strawberry runners; a plant of _Potentilla reptans_; creeping grasses;
_Poa bulbosa_ roots from the seaside; potato. Earth nuts; lily bulbils;
Timothy grass; cow-wheat (_Melampyrum_); yellow rattle (_Rhinanthus_);
clover dodder (_Cuscuta trifolii_); flax dodder (_Cuscuta epilinum_);
mistletoe. Root fibres of various plants. Mustard seed sown on flannel.
CHAPTER III
_TREE STEMS_
“If thou art worn and hard beset
With sorrows, that thou wouldst forget,
If thou wouldst read a lesson, that will keep
Thy heart from fainting and thy soul from sleep,
Go to the woods and hills! No tears
Dim the sweet look that Nature wears.”
+Longfellow.+
CHAPTER III
TREE STEMS
A walk through a wood on a bright day in February will afford us many
interesting intuitions about the growth of trees.
We are apt to think of winter as a dead season, and long for summer
days once more, that we may pursue our botanical studies; but as soon
as February begins there is already a secret work going on within the
tree-stems, the sap is rising from the roots, and this ascent is easily
to be traced if we look carefully at the trunks of those trees, such as
the oak, elm, and others, which have rugged bark. The wood within is
swelling; fresh layers of material will, a little later on, be added to
the inner side of the bark as a result of this ascent of the sap.
As the bark is hard and inelastic, it cannot expand in proportion, and
therefore has to crack and split in yielding to the internal pressure.
If we look for these fresh cracks, we shall see the clean new bark
within, which, before long, will harden and become of the same shade of
grey as the rest of the stem.
[Illustration: TURKEY OAK BARK.]
It is at this season, too, that the plane-tree sheds off its fragments
of bark in greatest quantity, as one may plainly see in the London
squares, where this tree grows so remarkably well. Its stem is always
peeling more or less throughout the year, and possibly that fact may be
one of the reasons of its flourishing so well in the midst of smoke and
fog.
[Illustration: SCOTCH FIR BARK.]
Trees shed their bark in many different ways.
A reference to the illustrations will show the concentric rings of the
horse-chestnut, the square pieces of the sycamore, which are due to
the cleavage being both vertical and horizontal, the hexagonal shape of
the divisions of the Scotch fir, the rugged bark of the Turkey oak, the
sycamore and other species.
[Illustration: SNAKE-BARK MAPLE.]
Where a woodpecker or a nuthatch has bored a hole into the living wood
of a tree-stem, it is interesting to watch how the injury is repaired.
New bark begins to form at the edges of the wound, and to this a layer
is added each year, until at last the hole is filled up, and only a
scar is left to show where it once existed.
[Illustration: +TURKEY OAK STEM+ (_struck by lightning_).]
I have been able to watch this repairing process going on for twelve
years in the case of a Turkey oak, which was injured by lightning. I
was watching the progress of the storm from one of our upper windows,
and happened to be looking at this particular tree in the park, when
out of a lurid cloud above it, a streak of forked lightning descended
upon the tree, and rent off the bark of one side from the top to the
bottom, carrying away portions of it to a distance of fifty feet or
more, leaving a white gash which looked pitiful enough for many months.
Year by year a wave of new bark rolls on, covering the bare place by
slow degrees, but it is never destined to be quite healed in this case,
for the inner wood was killed to some extent by the lightning, so it
has become a home for the boring beetles, who are riddling it with
holes wherein to lay their eggs.
[Illustration: PLANE-TREE BARK.]
[Illustration: HORSE-CHESTNUT BARK.]
Such a tree becomes a happy hunting ground for the woodpecker, who is
attracted by the insect diet he finds there. The large holes he makes
in getting at his prey will let in the rain, so that after a time the
moist rotten wood forms a suitable place for various fungoid growths,
and all these agencies work together for the destruction of the wood
until the tree becomes a hollow stem, and the leafage above is solely
produced by the sap carried upward by the bark.
[Illustration: WHITE POPLAR BARK.]
[Illustration: SYCAMORE BARK.]
Let us inquire a little more carefully into the formation of a
tree-stem, and the different parts of which it consists. Some rather
hard names are given to the four principal parts of a tree trunk but,
by reference to the plate, and by knowing the meaning of the names,
I hope they will soon be mastered, and then our future walks in the
woods will be fuller of interest than ever, when once we understand
something about the hidden work that is being carried on in those grand
old trunks around us. A tree may be compared to a large manufactory. As
we stand outside the building we see the brick walls and the roof, and
smoke is coming out of the chimneys. We know that a great deal of work
is being done inside, and carts are leaving its doors laden with the
products of the machinery within, but how the work is done we cannot
tell from the outside. We perhaps desire to obtain this knowledge, and
under the guidance of the manager, we are taken from room to room and
see the marvellous processes by which raw material is converted into
exquisite fabrics, or it may be clay is turned into priceless china
or porcelain. We leave the building full of wonder at the things we
have seen, and those particular manufactures will ever afterwards be
invested with a special interest for us, because we have seen with our
own eyes how they are produced.
[Illustration: TREE-FERN BARK.]
Just in the same way we shall look upon trees in a new light, if we are
able in some measure to follow the processes nature is carrying on in
them year by year so as to ensure the foliage, flower, and fruit, which
minister so much to our pleasure and profit.
The four names we must learn about in order to understand the
formation of wood are these. First the outer bark, called epidermis,
from two Greek words _epi_ upon, and _derma_ the skin. _Cortex_, a
Latin word meaning bark. Fibro-vascular bundles; this long phrase
refers to certain threads or fibres which exist in stems and give
them toughness and elasticity. From such fibres in the flax plant we
obtain linen, and from the hemp fibres ropes are made. _Fibro_ comes
from the Latin _fibra_, a thread or fibre; and _vasculum_ is Latin
for a little vessel; we know the word better, perhaps, in another
sense as _vasculum_, the tin box in which botanists place their plant
collections.
These thread-like vessels are well called bundles, because they exist
in little masses in the substance of the stem.
Most young people know what is called King Charles’s Oak in the stem of
the brake fern, so plainly seen when it is cut across with a penknife.
The dark markings are the ends of the fibro-vascular bundles which
happen to resemble an oak tree in form, though some think them more
like an eagle with outstretched wings, so the fern is named _Pteris
aquilina_, from _aquila_, an eagle.
The fourth word is pith, the white substance in the centre of the stem,
which can readily be seen by dividing a piece of elder branch, when the
middle will be found full of white pith.
When we have these four parts of the stem clearly in our minds it will
be possible to go on with our study and learn about the spaces between,
which are filled with different kinds of cells.
The honey-comb formed by bees consists of small cells, little hollow
spaces in which they store the honey or bee-food. Woody structure
consists largely of cells of various shapes to contain sap and other
substances. A beautiful specimen of cell net-work may be obtained
by placing a thin slice of either white or yellow water-lily stem
on a piece of glass and, holding it up to the light, a fine sort of
lace-work will be seen. These are the cells which convey air and water
through the stem up to the leaves and flowers. Or if we examine a
flower petal with a magnifying glass we shall find it to be entirely
composed of minute cells.
[Illustration: STEM OF YELLOW WATER-LILY.]
[Illustration: STEM OF WHITE WATER-LILY.]
In these little spaces are stored very many and very different
materials, all necessary to the growth of a tree; we shall try and
learn about them by degrees; at present we must endeavour to obtain a
clear idea of their structure.
A tree-stem increases in size yearly by the growth of fresh cells
within the outer bark, and this active increase of tissue is due mainly
to what is called the cambium layer, which is developed only in the
spring and summer and does not exist in winter; it forms bast, or
phloëm, on the outer side next the bark, and on the inner side next the
pith it creates woody tissue.
Our English lime tree has a layer of fibre beneath the bark which is
worth examination; it is the same in character, but not so wide or
strong, as the bast which we import from Russia in mats to protect
vegetation from frosts. Squirrels are very fond of this soft material;
they strip it cleverly off the branches of our lime trees to form a
warm lining for their nests.
It is easily found by cutting the outer bark off any small branch of
lime within reach, when we can peel off the inner layer of bast, or
phloëm, as botanists call it.
The phloëm from the lace-bark tree of the West Indies is like the
finest possible net-work, and is used for many ornamental purposes.
_Liber_ (Latin for the inner rind of a tree) is another term applied to
this cell formation.
The study of different forms of woody fibre will be found most
interesting.
I obtained one of my best specimens of it by placing a very old Swedish
turnip in water for some months until the soft parts had melted away
and only the round ball of fibre remained. If any one wishes to follow
my example I would suggest placing the turnip and its pan of water in
some outhouse where its perfume will not incommode any one. A maid
came to me one day with a sad account of a fearful smell which had
been noticed for some time in a lumber-room at the top of the house,
and very naturally she thought that the plumber should be called in
to remedy the evil. I had almost forgotten my interesting skeleton,
but in due time I traced the odour to its right cause, and the turnip
was banished to a distant spot, where many washings and some soaking
in chloride of lime changed it into a really beautiful specimen of
woody fibre. I possess now only a quarter of it, for botanists have so
earnestly begged for pieces of it that I have been persuaded to share
it with them.
I have sometimes picked up on the seashore old cabbage-stems bleached
to a delicate ivory white, forming really beautiful instances of woody
fibre. These we can prepare for ourselves, if desired, by soaking the
stems in water until they can be brushed perfectly clean, and then
bleached by mixing a little chloride of lime in water and letting them
soak in it till they are white and free from odour.
In a manufactory there must of necessity be a series of windows on
the different floors, not only to let in light but for purposes of
ventilation. Now, the processes of tree-growth are carried on without
light in the stem, but air is necessary, and it is supplied by means
of small apertures called lenticels. These are not open holes, but
are more like gratings which admit a small amount of air through
loosely-packed cells.
These lenticels are the small brown specks which may be traced in
great numbers on the young branches of almost any tree. They remain
open through the spring and summer, admitting the needful air to the
interior of the bark, but when the tree-growth is over for the season,
and air is no longer needed, a layer of cork forms within the lenticel
which entirely shuts it up and keeps out the wintry cold. Thus it
remains sealed up till, by the growth of the cambium layer in the
following spring, the corky barrier is split open and air is again
admitted.
These lenticels are nature’s ventilators, opening and shutting in this
curious way in order that the manufacture which is going on beneath the
bark may receive from the outer air the various gases essential to the
work which is being carried on within.
I have said that many and various things are stored in the stem-cells
of trees. It would occupy too much space to attempt to make anything
like a complete list of the liquids and solids which are obtained from
trees, but I will enumerate a few of those with which we are familiar
from their usefulness in every-day life.
Turpentine is obtained from various kinds of firs—the Scotch fir,
larch, and others. Burgundy pitch from the spruce fir. A kind of tar is
also prepared from Scotch fir and larch. From various kinds of cinchona
we obtain quinine, so valuable as a remedy for fever. Camphor is a
product of a Chinese tree. Tannin, by which skins are converted into
leather, is obtained from the bark of the oak-tree. A kind of sugar is
made from the sap of the maple, which is largely used in America. Gum
arabic and a great number of gums used in medicine are produced by
foreign trees of various kinds. The interior pith of a West Indian palm
tree produces the sago of commerce.
Stems, like every other part of a plant, are to be seen in endless
variety when we come to examine them for ourselves. In common garden
plants such as the calceolaria and petunia, the consistence is soft,
and such stems are known as herbaceous; these generally die down in
autumn. Roses and rhododendrons have stems of a harder and more rigid
character, and seem to be intermediate between the soft herbaceous
stems and tall tree trunks.
If in some country ramble we resolve to make the trunks and bark of
trees our study, we shall find much that is interesting and well worthy
of observation.[7]
[7] For instance, I have noticed some curious examples of trees growing
together. A Turkey oak and Silver fir in my own grounds are closely
united at the base. The fir-seed and the acorn must have germinated
in such close proximity that the stems have almost grown into each
other. The group of beeches shown in the plate gives another example of
interlacing stems and roots.
[Illustration: GROUP OF BEECH-TREES WITH INTERLACING STEMS AND ROOTS.]
The Lombardy poplar, with its tall bending stem, the graceful willow
and the silver birch, contrast strongly with the thick and sturdy
trunks of the elm and oak. Even these two differ, the wood of the elm
being short and brittle, whilst that of the oak is hard and flexible.
Again, we may note the slender drawn-up stems of trees growing thickly
together in a wood, where light and air are in a measure shut out,
and compare them with other specimens standing in a park in free air
and light. There we see trees, growing as nature intended, with grand
sturdy trunks and welldeveloped branches spreading out on all sides.
Lastly, in this chapter, we may note the climbing stems; these are
especially numerous and diversified in their manner of growth. Almost
every part is modified and adapted to assist the stem to climb. The
common ivy develops upon the surface of its stem numerous rootlets, and
by their clasping nature the ivy is enabled to ascend the smoothest
tree-trunk. The hop and the convolvulus climb by means of their habit
of twining around some rigid stem or twig. Then the peas and vetches
send out little clasping tendrils in the place of leaflets, whilst that
lovely ornament of the hedges—traveller’s joy—climbs by occasionally
using the leaf stalk for a clasping holdfast. Not less interesting are
the plants that climb by means of their hooks; the common bramble is
of this kind; it scrambles over the hedge in a very enterprising and
aggressive manner, while its spines and hooks effectually prevent it
from slipping back.
[Illustration: CONVOLVULUS.]
A very highly developed organ of climbing is that to be found upon
the stems of the small Virginian creeper (_Ampelopsis Veitchii_). On
the points of its small tendrils we shall discover little globular,
crimson-coloured pads, which, when pressed against a tree or wall,
secrete a kind of vegetable glue. This fixes the tendril and enables
the weak slender stem to climb upwards. In these instances, as well as
others mentioned earlier in the chapter, we have again evidences of how
wonderfully plants are adapted to their wants and environment.
Things to observe and collect:—The various ways in which trees shed
their bark; how trees repair holes in the stem; fibres in flax stem and
in hemp; specimens easily obtained by sowing linseed and hemp-seed;
section of brake-fern stem; section of elder stem; thin section
of white or yellow water-lily stem; flower petal; piece of bast
matting; West Indian lace-bark; turnip and cabbage stalk prepared as
specimens of woody fibre; lenticels on various trees; suitable leaves
for skeletonising—holly, magnolia, tulip-tree, pear, poplar, aspen,
mahonia, plum and maple; suitable capsules—poppy, stramonium, henbane,
winter-cherry, campanula, and the calyces of the yellow-rattle.
CHAPTER IV
_LEAVES_
“These naked shoots
Barren as lances, among which the wind
Makes wintry music, sighing as it goes,
Shall put their graceful foliage on again,
And more aspiring, and with ampler spread,
Shall boast new charms, and more than they have lost.
Then each, in its peculiar honours clad,
Shall publish even to the distant eye,
Its family and tribe.”
+Cowper.+
CHAPTER IV
LEAVES
We have learned in the previous chapters that the roots are the means
by which a plant gathers out of the earth the various constituents
which are needful to maintain its life.
The leaves have also to do their part in collecting from the air such
gases as are required to effect the processes carried on within the
substance of the leaf.
The leaf is really the digestive organ of the plant; it feeds,
breathes, and gives off in the form of vapour any excess of water
not required for its work. For these purposes sunlight and air are
necessary.
A leaf consists of a stalk, called a petiole, and the flat green part,
which we may call the blade.
If we hold a leaf up to the light we see a network of veins, and it is
by their help the leaf becomes a broad expansion of tissue, so exposed
that it gets the fullest possible benefit from the sunlight and air.
This fibrous network gives strength to the leaf, and answers to the
bones in animal structure.
[Illustration: NETTED VEINS.]
The fibro-vascular bundles, which we see in the stem, go up through
the petiole, and branch out in a beautiful and regular manner. We may
observe this arrangement very clearly in a skeleton leaf, the midrib
forming a backbone to the whole structure, while the smaller veins tend
off to the edge of the leaf, and then overlap so as to form a system of
girders supporting the edge, and preventing the wind from tearing the
delicate tissues into shreds.
The arrangement of leaf network is called venation, and by a glance at
it we can at once see to which of the great divisions in botany a plant
belongs. If the fibres are straight and run parallel to each other
without being netted, then we know the leaf is that of a plant which
begins its life with only one seed-leaf; such are all the species of
corn and grass, bulbs, palm-trees, bananas, and others.
The long name applied to this division of plants must be explained, as
it is a term we cannot do without, and I must own it looks formidable
until we understand its meaning.
[Illustration: MONOCOTYLEDON.]
The first leaf that comes out of a seed is called a cotyledon, from
_kotúle_, a cavity, or cup. The Greek for one is _mónos_, so plants
with one seed-leaf are called monocotyledons.
If we sow a date-stone or a few seeds of Indian corn in moist soil they
will grow readily, and afford us nice little specimens of a one-seed
leaf-plant.
If we see that a leaf has netted veins, then we know its seed produced
two leaves at first,[8] so plants belonging to this great division are
called dicotyledons.
[8] The Maranta and a few other plants are exceptions to this rule.
[Illustration: DICOTYLEDON.]
In order to watch the growth of two-leaved seedlings, we may select a
broad bean, or some of the seeds out of tamarind jam; either will grow
readily in a pot of earth, if it is placed in a sunny window, or near a
stove, and kept moist.
Orange and lemon pips may sometimes be found sprouting within the
fruit, and either of these seeds will germinate, and form charming
little evergreen plants to brighten a town window-ledge.
[Illustration: TAMARIND SEEDLING.]
Now we need not be afraid of those two long words which are used to
describe one-leaved and two-leaved seedlings, since we know their
meaning, and it will be interesting when we come across some new plant
to see to which division it belongs, because knowing that will mean
knowing a great deal besides.
All our English trees (with the exception of the firs, which have
many seed-leaves) are dicotyledons; they increase their stems from
the outside, and are therefore called exogens, and most of our plants
belong to this division.
The monocotyledons increase from the centre, that is to say, the
second leaf grows out of the first, and the third leaf and its stem
grow out of the sheath of the second leaf, and so on; and this is
the law of their growth, whether they be corn plants or palm-trees.
These sheathing leaves and the straight veins will always enable us to
recognise a one-seed leaf-plant at sight.
The development of the stem has a marked influence upon the arrangement
of the leaves; these, in such plants as the cyclamen, sundew, or
primrose, are said to be radical; that is, growing from the root.
Close observation will reveal the cause to be the non-development of
the internodes, the leaves being crowded upon a very short, suppressed
stem, and thus we get the beautiful little rosettes we find in the
daisy and plantain. When the stem is of greater length the leaves
are ranged at definite intervals, the spaces between the leaves (the
internodes) varying in length in proportion to the size of the leaf.
Small leaves are thus much thicker upon the tree than larger ones.
This will readily be seen if we compare a branch of sycamore with one
of elm, the former having its large leaves much further apart than the
latter.
Then, also, the arrangement of leaves upon the stem (_phyllotaxis_)
varies much. If we take a spray of beech we shall find that its buds
are placed alternately on either side of the stem, so that the third
bud is exactly below the first, and the second bud is in a line with
the fourth, and so on. This is also the plan of the elm, hazel, lime,
hornbeam, and many other trees. In the alder and whitebeam the buds
occur in three rows, and in some of the willows in series of eight.
The leaves of the horse-chestnut are borne in pairs on alternate sides
of the stem, and this plan is common to a number of plants, especially
those of the type of the dead nettle and speedwell.
Quite a distinct arrangement is that to be found in the woodruff and
bedstraws, where the leaves are placed in a ring (a whorl) at regular
intervals on the stem.
The botanical student should carefully observe the differing methods
of leaf arrangement, since, as branches are developed from buds, the
varying order in their position must naturally modify the general
aspect of a tree, and has also much physiological importance. We shall
find that buds are so placed that each leaf shall receive its full
share of sunlight and air, for it needs this position in order to
enable it to carry out the wonderful work of assimilation which it has
to perform.
The upper surface of a leaf is covered by a thin layer of cells, known
as the epidermis (or skin); this does not prevent the light from
falling through, and its outer surface is protected by a thickening,
known as the cuticle. This is of great use in controlling the escape of
moisture, otherwise the leaf would soon shrivel up in a hot sun. In a
young seedling leaf the cuticle is not developed, and it can therefore
breathe out moisture very rapidly; later on, when the cuticle is
formed, it controls the escape of moisture, which can then only exude
through the under surface of the leaf.
We can easily peel off a portion of the skin from the under surface
of the leaf, and if we place it in a little water between two pieces
of glass and look at it in a microscope we shall see that it consists
of an extremely thin layer of cells, with numbers of little openings
called stomata (from the Greek _stoma_, a mouth), answering somewhat
to the lenticels to be found in young tree-stems, only those are solely
for the admission of air, while these little mouths are to let in and
out not only air, but water, vapour, and oxygen.
These stomata look like little crescent-shaped slits with a curved cell
on either side, and as they curve more or less, the mouths are opened
or shut as the plant may require. These little mouths play a very
important part in the economy of the leaf, and they exist in immense
quantities on its under surface.
[Illustration: STOMATA.]
It has been calculated that a million stomata exist on a single leaf
of the lime tree. When the root has taken up more moisture than is
required, then it is the office of these pores, or stomata, in the
leaf to give out this extra water in the form of vapour, and we can
thus see how the action of leaves must influence climate. If forests
are recklessly cut down, the bare country, with no foliage to throw
moisture into the air, may become an almost barren desert, and again
in marshy places, where the air is too damp, a wise reduction in the
number of trees may alter the climate to a healthy condition.
Remarkable results have been obtained by planting the Australian
gum-tree, _Eucalyptus globulus_; it thrives well in malarious places,
and at once produces a marked hygienic change in the air. A Monsieur
Gimbert relates that “A farm some twenty miles from Algiers was noted
for its pestilential air, and in the spring of 1867, 13,000 eucalyptus
trees were planted there, since which time not a single case of fever
has occurred.
“The gum-tree grows rapidly and absorbs as much as ten times its weight
of water from the soil, and emits camphoraceous antiseptic vapour from
its leaves. It is therefore often called the fever-destroying tree.”
Experiments have been made to try and find out how much moisture is
really given out by leaves. It was found that a sunflower three and
a half feet high, with a leaf expanse of over five thousand inches,
exhaled one pint of liquid in the course of the day.
No wonder, therefore, that trees tend to make the air damp.
Each stomate leads into air spaces between the cells, and is thus
connected with the interior of the leaf.
[Illustration: LEAF SECTION.]
The tissue and cells of a leaf (bifacial)[9] can be understood by
reference to the accompanying diagram. Between the upper and under
surfaces of a leaf there is a layer, more or less thick, of soft green
tissue known as _mesophyll_, and if we hold a leaf to the sunlight we
shall see the veins traversing this tissue.
[9] That is, a leaf like the beech or sycamore, having an upper and
under surface; vertical leaves, like the iris, have palisade tissue on
both sides.
The upper part of the mesophyll consists of elongated cells arranged
at right angles to the surface, and placed so evenly parallel to each
other that they have been compared to the pales of a fence, and are
called palisade tissue. These cells contain a quantity of the green
substance called _chlorophyllon_ (from _chloros_, green, and _phyllon_,
a leaf), so named because to this bright green substance we owe all the
lovely verdure of our woods and gardens.
Below this palisade tissue is another of quite a different form,
consisting of large spongy cells, and therefore known as spongy tissue.
In its intercellular spaces are stored those secretions which make
certain herbs, such as thyme, marjoram, and others so fragrant when
bruised.
The chemical changes which are ever going on in these various layers,
require a constant supply of the outer air, and this is secured by the
little openings, called stomata, on the under surface of the leaf,
which have been already described; these constitute the breathing
apparatus of the leaf, for they open and shut, and regulate the
supply of air into little air chambers, from which it passes into the
structure of the plant.
Before going any further I must try and explain a little about the
wonderful substance called protoplasm.[10]
[10] Greek: _proto_, “first”; _plasma_, “anything moulded.”
If we have ever watched a potter at work, we know he takes a lump of
clay and moulds it according to his purpose, into a rough pot, or a
lovely vase; now protoplasm seems to be just such a foundation material
from which the Divine Creator causes animal and vegetable forms to
proceed. _First material_ seems to me to be a term that actually
expresses the meaning of the word protoplasm.
It lines the cell walls of leaves, it is capable of forming fresh
cells, it can absorb moisture and other matters, it contracts and
expands, it has power of movement, as one may readily see when a
portion of a leaf is placed in a microscope, so as to show the grains
of bright green chlorophyll circulating in the lining of each little
cell.
Learned volumes would be needed to explain the nature of protoplasm, so
I must be content with these simple facts about its nature, and proceed
to the chemical action going on in leaves.
In ordinary atmosphere there is a very small quantity of a gas called
carbon-dioxide.[11] The leaves absorb this gas from the air, and
because there is so little of it, each tree needs to spread out an
immense amount of foliage, that it may drink in, by its means, all the
carbon-dioxide that can possibly be obtained.
[11] Carbon meaning charcoal, and dioxide meaning two parts oxygen.
Sometimes called carbonic-acid gas.
When this gas comes in contact with the chlorophyll in a leaf, one part
of the oxygen is set free, and returns to the air in a pure condition,
thus making it more healthy for us to breathe; then the carbon and the
remaining oxygen combine with water in the leaf cells, and form starch,
the leaves retain the carbon, to build up their own structure; it
enters indeed so largely into the composition of vegetable substance,
that in some cases if we could burn one hundred parts of it, fifty
parts of the ashes would prove to be carbon or charcoal.
In a rough sort of way we may see for ourselves how much carbon there
is in woody fibre, by lighting an ordinary wooden match and letting it
burn itself out; the black portion that remains will be a piece of
charcoal not very much smaller than the original match.
Of course, in the process of burning, the match has lost the resin, and
other organic substances which were stored up in the cells of the wood;
all these have passed into the air, and only the carbon remains. If,
however, instead of this slow manner of combustion, we had set light to
a whole box of matches so that it burnt fiercely, the flame would have
been strong enough to consume the charcoal, and nothing would then be
left but mineral ashes.
When charcoal burners are at work in a forest, we may see them making a
stack of wood, which they cover with a thick layer of clay so that the
wood may burn away very slowly; in this case the charcoal will be left
in the same way as when we burnt the single match.
As long as the upper side of leaves are soaking in the sunlight, starch
is being formed, as I have described; but during the night the starch
thus formed is dissolved, and passing through the leaf fibres finds its
way into every part of the plant, either to be used in forming new
tissue, or else to be stored up for future use.
The net-work of veins act as a service of tiny pipes, to convey the
liquids up and down the petiole (leaf-stalk).
Generally the water given off from the stomata is in the form of
vapour; but in some plants drops of water exude from the apex or point
of the leaf through the water pores. In _Saxifraga crustata_, there
are pores round the edges of the leaves, through which water, highly
charged with lime and other salts, passes out, and as it evaporates a
white deposit of lime remains which is quite visible in the form of a
frosted edging to the leaves.
There is an American plant called the jewel-weed, which shows to
perfection this power of distilling drops of water. I will quote a
short description of its appearance at night-fall.
“Upon the approach of twilight, each leaf droops as if wilted, and from
the notches along the edge, the crystal beads begin to grow until its
border is hung full with its gems. It is Aladdin’s lantern that you see
among a bed of these succulent pale green plants, for the spectacle is
like dreamland.”[12]
[12] “Sharp Eyes,” by Wm. Hamilton Gibson.
A very similar effect may be observed if we visit a plant of
Lady’s-mantle (_Alchemilla vulgaris_) at early morning after a warm
dewless night; each leaf will be found beautifully decked with dewdrops
at equal distances round the edge of the leaves where the pores have
exuded the moisture with which they are charged.
Nasturtium and fuchsia may also be examined for this purpose and will
show exudation from their leaf pores.
If a small quantity of wheat is grown in some cocoa fibre, it will
illustrate this power of giving off water, for when the little blades
are a few inches high, they will be found each morning tipped with a
large dewdrop, the result of exudation during the night.
In countries where the sun is intensely hot, if the leaves of trees
were to be exposed to its full power, they would probably wither, and
vegetation would perish.
[Illustration: YOUNG SHOOT OF EUCALYPTUS.]
Against this danger some trees are enabled to make special provision,
by changing the form of their leaves, and their mode of hanging on the
branch. In Australia, for instance, where the sun is almost vertical,
the acacias and eucalyptus trees, instead of holding their leaves flat
or horizontally as trees do in England, so that they may catch every
ray of sunlight, avoid the heat as much as possible, by holding them
edgeways to the light.
[Illustration: MATURE FORM OF EUCALYPTUS LEAVES.]
While eucalyptus trees are young, and partially shaded by surrounding
vegetation, their leaves are flat and oval, and English seedlings
of this tree usually retain such leaves from five to ten years, our
climate not being hot enough to require the mature form of leaf which
hangs vertically, and is of an entirely different form.
Reference to the plates will show a young shoot of _Eucalyptus
globulus_ and a branch of the older leaves, with their edges only
exposed to sunlight.
The curved sickle-shaped leaves of the eucalyptus afford very little
shade to the traveller in Australia for this reason, that only fine
intercrossing lines of shadow are seen on the ground. To make this
clear, let my readers take a sheet of notepaper out of doors on a sunny
day and hold it perfectly flat, so as to expose it to all the sunlight
it can receive upon its surface, as if it were a growing beech-leaf,
and it will throw a large shadow on the ground. Then hold it edgeways
to the sun, and it will form the kind of thin line of shadow that would
be cast by a mature eucalyptus leaf.
Preparation for the fall of the leaf begins in spring, when a fine
line or ridge may be traced just below the junction of the leaf with
the stem. This dark line is in reality a thin layer of cork, which,
during the summer months, continues to grow inwards to form in due time
a covering for the bare place on the stem that will be left when the
leaf falls off; this is called the leaf-scar.
It is interesting to watch this line, growing more and more visible as
the year goes on.
Another curious fact is, that some of the starch which the leaves have
been making during the summer, becomes stored up in autumn at the base
of the leaf-stalk, so as to afford nourishment to the bud which will
arise out of the axil of the leaf. When a weak solution of iodine is
applied to it, this starch turns blue, and in this way its presence can
be ascertained.
The fall of the leaf appears to take place mainly because the starch
has the effect of softening the cells of the leaf-stalk; as it dries up
it loses its hold of the twig, and either the wind or a slight frost
will suffice to bring the leaves down to the ground in showers.
Another reason for their fall is, that their year’s work is done. Like
good servants, they have been hard at work all through the summer and
autumn months, taking in stores of nourishment for the benefit of the
tree, and giving out volumes of oxygen, so helpful for the maintenance
of human life. They have secured and laid up sufficient nutriment
for the development of the next year’s buds, and having done this,
their special office being at an end, they fall beneath the tree to
become leaf-mould, which, in its turn when fully decayed, will yield
nourishing elements to be carried by the winter and spring rains to the
tree roots.
I might add many more useful objects which we owe to trees, and I
commend it to my young readers as an instructive study to try and make
out a complete list of the useful products of our English trees. I
imagine we do not yet know all that might be obtained from them, new
discoveries continue to reveal their value in the way of medicines;
for instance, the crystals of the willow (called salicine) are now
frequently prescribed as a remedy for rheumatism. Euonomine and many
others might be included amongst the valuable gifts which nature has
stored in the cells of tree-stems.
Specimens to be obtained:—Leaves with straight veins, such as grass
or corn, hyacinth, narcissus, or any bulbous plants; leaves with
netted veins, such as oak, ivy, vine, &c.; monocotyledon seedlings;
dicotyledon seedlings. Leaf-skin to be examined through a microscope,
in order to see stomata, chlorophyll, network, and cells. Examine
waterpores in leaves when exuding moisture. Observe shadows thrown
by leaves held flat and edgeways to the sun. Compare young and old
eucalyptus leaves. Observe line of cork below leaf-scars.
Leaves can be made into beautiful skeletons by soaking a good many
together in a pan of soft water until the upper and under surfaces of
the leaves are sufficiently decayed to be easily removed by a soft
brush; the fibre which is left can then be bleached with chloride
of lime. When mounted with fine wire these skeleton leaves form an
interesting group to place under a glass shade.
CHAPTER V
_BUDS_
“Oh! who can speak the joys of spring’s young morn,
When wood and pasture open on his view,
When tender green buds blush upon the thorn
And the first primrose dips its leaves in dew.”
+Clare.+
CHAPTER V
BUDS
How we watch for the buds as tokens of the coming spring! We delight to
see them daily growing larger, and opening out their leafy treasures to
the sun.
The re-clothing of the trees has always an element of wonder about it;
the change is truly a resurrection; a few days of warm sunshine and
gentle rain, and then the dry, dead-looking branches begin to bud and
blossom as if by a miracle.
We may, however, trace the secret of this sudden change, if we look
back to the processes Nature was carrying on during the previous
summer, and we may learn from her many a useful lesson of foresight and
preparation.
If during the summer we lift up the branch of any deciduous tree
and search amongst the leaves, we shall find that the buds for the
following year are already there, waiting to be developed in due time.
When the leaves turn dry and sere, they fall off and leave the buds to
be hardened and matured by the rain, snow, and frost of winter.
Certain species of Turkey oak, young beeches, hornbeams in hedges, and
other trees, appear to retain their leaves, to some extent, as if to
protect the buds until the rising sap in spring loosens their hold upon
the branches, and makes them fall off.
The plane-tree appears to be an exception to most trees in the curious
protection it affords its young buds. If we search for these in the
summer or autumn, they are not to be found, for the leaf-stalk is so
swollen and hollow at the base as to enclose the bud within it; even
when the leaf falls off, the bud is covered by a tough outer case
coated with resin, and within are many fur-lined scales. When these are
removed we see the tiny leaves wrapped in silky coverings, and when the
warmth of spring enables them to expand, their under surfaces have
such a thick coat of down that the plane is known in some countries as
the cotton-tree. From its fruit being in the form of hanging circular
balls, its name in America is the button-wood. The need of this
special protection against cold is shown by the fact that if severe
frost returns after the leaves have expanded, they frequently shrivel
and perish. Some Japanese maples have the same arrangement of hollow
leaf-stalks to contain the buds.
[Illustration: OAK IN WINTER.]
When buds are situated at the end of a branch they are called terminal,
and their office is to increase the length of the branch.
When they grow in the axil of a leaf (that is, where the leaf-stalk
joins the stem) then they are called axillary, and as they grow out and
form fresh stems and leaves, the branch broadens on either side.
[Illustration: OAK IN SUMMER.]
Seeing that the branches of a tree thus spring from the buds, it
follows that the position and development of the buds upon the stem,
as we tried to show in the last chapter, have much to do with the
ultimate shape of the tree. The development of the axil buds, as well
as of the terminal bud, gives rise to a branched tree like the oak;
these buds, however, are often erratic, and in some trees the terminal
bud of the shoot is often suppressed and the axil buds grow with extra
vigour, whilst in other instances the terminal bud grows strongly and
the axil buds either grow feebly or are altogether suppressed. In the
bamboos, palms, and sugar-cane we get good examples of this terminal
bud-growth, the axillary buds being suppressed; the suckers that grow
from the axils of the lower leaves of the palm are often evidence of
the presence of axillary buds, although they are, as a rule, dormant.
We are all more or less familiar with the character of ordinary forest
trees, the rounded outline of the oak, the slender sprays of the birch,
the spreading branches of the beech, but perhaps we may not have
remarked how much these variations of form are due to the position
of the buds upon the branches. We will suppose that on a winter’s
day we are looking at the tracery of some elm-branches against the
sky; the form of each branch shows that the terminal bud in this tree
usually ceases to grow, and allows the lateral shoots to increase in
length, and take its place; this produces short, twiggy branches, and
a stem which makes a tall tree rather than a wide-spreading one. The
horse-chestnut, again, produces its flowers in the terminal buds; this
arrests their growth, and side shoots have to grow on instead, thus
usually giving height rather than breadth to the tree. We may note
the differing outline of the willow, birch, and many others where the
terminal buds do not cease to grow, but each year continue to add to
the breadth as well as the height of the tree.
In pine-trees the buds are produced at the ends of the branches, and
several shoots proceed from one bud.
The spiral arrangement of leaves is well seen in a young coniferous
shoot, also in the flower-bud, and especially in the fir-cone itself,
in which an ever-varying double spiral can be traced.
Loudon remarks, “The perfection of a fir consists in height rather
than in lateral expansion; buds are produced very sparingly and nearly
always at the extremities of the shoots. Provision is thus made for the
upward growth of the tree more than for side expansion.”
When we speak of a coniferous shrub having lost its leader, we mean
that the terminal bud on the topmost shoot having been broken off, one
or more of the lower branches must rise up and take its place, and
thus lateral buds in time become terminal and grow upright instead of
sideways.
A silver fir, that I have been observing for years past, bears such a
crop of heavy cones on its slender upper branches that the leader is
almost invariably broken off by the weight, and the lateral shoots have
to take its place, to the great detriment of the central stem, which is
twisted and curved out of shape by the efforts the tree makes to repair
its terminal shoot.
In other trees, again, the unfolding of all the buds is nearly
simultaneous, but in the fir tribe the bud which terminates the summit
of the tree and is destined to form its leading shoot and increase its
height is developed last; this delay seems a provision of nature for
the safety of the most important shoot which the tree can produce,
ensuring its height rather than its breadth, and the production of
timber by the preservation of its permanent trunk rather than by its
temporary branches.
If a willow is deprived of the upper part of its stem and so made a
pollard tree, it develops a bushy head of small stems which spring from
the other buds thrown out to repair the loss of the central stem. This
pollarding is often resorted to in order to obtain wood of the right
kind for basket-making, and young ash trees are thus treated, so that
slender rods suitable for hop-poles and tool-handles may spring from
the lopped stem.
When buds are found growing on any other part of a plant except those
just mentioned, they are called adventitious buds. These may be found
growing on the edges of the leaves of the marsh tway-blade; they also
spring out of the flat surface of the fronds of the viviparous fern.
Under favourable conditions every part of a plant will produce buds,
and, taking advantage of this fact, florists increase their stock of
succulent plants by putting the leaves on a wet surface, which induces
them quickly to send out buds and roots. Such plants as begonias,
gloxinias, hoyas, and sedums are readily increased by this mode of
propagation. Underground stems will often send out buds, and they
produce the underwood from the stumps of fallen trees.
We are all familiar with the suckers of trees which spring up in our
lawns and gravel paths often many yards away from the parent tree;
these all arise from active buds on underground stems. Gardeners
are always careful to prune away such growths at the base of their
wall-fruit-trees, since they rob their valuable peaches, nectarines,
and apricots of strength and nourishment. These well-named “suckers”
spring from the common stock upon which the choice fruit-trees were
grafted, as one may see by gathering a leaf from a sucker and comparing
it with a peach or nectarine leaf.
On the oak, chestnut, lime, beech, and other trees there are sometimes
to be found dormant buds in the form of rounded knobs covered with bark
and increasing in size with the growth of the tree; these, in the event
of other buds perishing, will start into active growth and do their
part in preserving the life of the tree.
Such woody balls when found on the oak are worth examination, as when
divested of their bark they show exquisite structure of woody fibre.
The small bulbils we find in the axils of lily stems, on the
cuckoo-flower, on _Dentaria bulbifera_, and on some species of Allium,
are all adventitious buds, which drop off in due time and become young
plants.
They are in many respects similar to bulbs, and if we cut one in half
and compare it with a divided hyacinth we shall see that they both
consist of over-lapping scales. In the onion these scales are fleshy
and succulent, but in most tree buds they are dry, hard membranes.
The pear and magnolia buds are secured against wintry cold by woolly
linings to the scales, and in the horse-chestnut they are covered with
a kind of resin which renders them impervious to moisture.
[Illustration: HORSE-CHESTNUT.]
It requires a careful use of the microscope to trace all that a bud
contains; I will therefore quote the words of a German naturalist who
dissected a horse-chestnut bud gathered in winter, and found that it
contained sixty flowers. It would be interesting to select a terminal
flower-bud of this tree; by taking it carefully to pieces one might,
with patience and using a powerful lens (or a microscope if one is
available), see for ourselves a good deal of what the writer describes:—
“Having removed the outer scales, seventeen in number, cemented
together by a gummy substance to render the bud waterproof, I
discovered four leaves surrounding a spike of flowers, so clearly
visible when magnified that I not only counted the number of flowers,
but could discern the pollen on the stamens.”
The winter covering of a bud, both the inner and outer scales, are
only a temporary protection in order to keep out moisture and keep in
warmth, so that as the sun begins to gain power, the gummy covering of
the bud melts and yields to the expanding pressure from within, when
one after another the sticky scales fall off, showing the young leaves
with their soft woolly surfaces; these leaves rapidly unfold and hang
droopingly until the midribs gain strength enough to hold them upright.
Evelyn remarked that, “As soon as the leading shoot of the
horse-chestnut has come out of the bud, it continues to grow so fast as
to be able to form its whole summer’s shoot, sometimes eighteen inches
long, in about three weeks. After this it grows but little more in
length, only thickens, becomes strong and woody, and forms the buds for
next year’s shoot.”
Buds have always been to me a most interesting subject of study; there
is much variety of character in them, and to those who observe them
closely they reveal in the autumn and winter what the tree is purposing
to do in the following season.
A beech-tree on my lawn bears its nuts only every second or third
summer, and in the previous autumn I can always tell whether the
squirrels are likely to be well off for food in the coming year, by
observing the size and shape of the buds. Those which contain the
flowers are round and bulky, whilst the leaf-buds are long and slender.
[Illustration: YOUNG BEECH.]
Embryo flowers are disposed in the buds in different ways. The
woodsorrel is rolled into a spiral, rose-petals are placed one within
the other, the pink is folded in five divisions, and others are pleated
and fluted into the smallest possible space. Perhaps of all others
the bud of the great Oriental poppy is the best example of exquisite
packing. Early on a summer’s morning you may see its huge green hairy
bud at the end of a stem several feet in length, and whilst you are
looking the sepals or calyx leaves suddenly divide and fall off, the
mass of vivid scarlet petals crumpled into a thousand folds begins to
open out, and before long the glorious flower, which is often as much
as seven inches across, holds itself erect in majestic beauty.
Those who possess a tulip-tree will find its opening buds reward
examination. The leaves are folded in half and bent double, a pair
of leaf-scales enclosing each of the true leaves. One may unpack the
entire bud until we come to leaves almost too minute to be discerned.
Young sycamore-trees often have buds of large size and brilliant
crimson colour; the foldings of their leaves are very intricate, and
form an interesting contrast to those of the tulip-tree. Hart’s-tongue
fern, arum, and pear leaves afford three very remarkable modes of
folding in the bud.
[Illustration: UNFOLDING ARUM LEAF.]
[Illustration: PEAR LEAF.]
[Illustration: UNFOLDING LEAVES OF HART’S-TONGUE FERN.]
Another point of character in buds is of considerable importance to the
horticulturist, namely, the fact that in some cases the value of the
flowers produced varies with the position of the buds. For instance,
the blossoms produced from the crownbud[13] of certain chrysanthemums
are poor and pale in colour compared with those grown on the side
shoots; the latter are therefore retained and fostered, so that from
them flowers of the finest description may be obtained.
[13] The uppermost bud of the central shoot.
In cultivating fruit-trees it is found needful not only to prune away
redundant branches which bear leaves only, but also where strong
woody roots are promoting the growth of leaf-buds, they also have to
be pruned, so that the check thus given to the growth of the tree
may result in the formation of fibrous roots, which will tend to the
production of flower-buds and a resulting crop of fruit.
I have often observed that the transplantation of trees leads to their
throwing out flowers in the succeeding year. This was notably the
case with an avenue of deodars which had overgrown my carriage drive;
they received a considerable check in being transplanted, but in the
following year their branches were covered with male catkins and some
few cones succeeded.
For this reason the removal of fruit-trees is not unfrequently resorted
to, as a means of inducing fruit-bearing.
So much vigour is stored up in the bud, that it will bear being
removed from one tree and inserted in the stem of another, within which
it will grow and become a part of the living tree. This is one of the
means by which we have obtained such an infinite variety of roses; the
buds from choice species being readily made to grow upon strong briar
stocks, and thus one may also see roses of several different colours
blossoming on the same stem. Choice varieties of fruit-trees are
cultivated in the same way by means of buds inserted in the bark.
Having observed how flowers are arranged in the bud, we may go on to
dissect incipient leaves and learn how they are placed.[14] We shall
find that the frond of the hart’s-tongue fern is rolled up from the
tip, the arum gracefully curved lengthwise. Pear leaves are rolled
from side to side towards the middle, and so is the primrose, but the
reverse way. Beautiful examples of curled leaves may also be seen in
the water-lily and banana.
[14] Venation.
In grasses the first leaves are equivalent to budscales, and protect
those which continue to grow from the centre, each one sheathing out of
the previous leaf after the manner of monocotyledons.[15]
[15] One seed leaf plants.
The colouring of buds is one of the lovely features of spring. Seen
against the blue of the sky, the coral red of the lime, sycamore,
and Japanese maple buds, cannot be passed by without notice. The
whitebeam has a beauty of its own for its buds are large and white
with downy coverings, giving promise of the future leaves which are so
light-coloured underneath, that the effect when they are blown aside by
the wind is curious and beautiful. The Germans call it _mehl-baum_ or
meal-tree, from its whitish downy leaves.
The variegated vine, sometimes seen in greenhouses, has exquisite buds
of pinkish crimson, with bright yellow stipules. By way of contrast,
I once placed some sprays of it in a glass with twigs of purple hazel
which are of a deep claret brown; they were not only opposite in
colour, but curiously different in habit, the vine holding its bud
erect, and the hazel as persistently drooping. These variations lead me
again to remark that, to a close observer, buds will be found to differ
much in character and to be well worthy of close attention.
I will mention some trees whose buds are specially remarkable for
beauty of form whilst unfolding. The mountain ash has very graceful
leaves when just emerging from the bud; they show on their upper and
under surfaces two distinct shades of green.
The unfolding weigelia buds are extremely pretty in shape, the leaves
being pointed and delicately curled.
I need hardly mention the beech; nothing can be more exquisite than a
spray of its opening buds with their silky fringed young leaves and
crimson leaf-scales. I look forward every spring to the joy of watching
the unfolding of these caskets.
A warm shower or two and some sunny days cause them to expand with a
rapidity which seems magical, and one almost regrets to find the beauty
of the buds in their early stages so quickly passing away. The ash
attracts notice by its jet-black buds, and the wayfaring tree by the
delicate venation of its young leaves.
I cannot refrain from mentioning another beautiful effect arising from
young buds in the case of a _Picea nobilis glauca_, which long name
simply means a sea-green silver-fir, standing on our lawn. In the
summer its terminal buds are a very pale sea-green, and as they grow
and are seen against the dark green of the rest of the foliage the
effect is very curious, as though each branch had become tipped with
frosted silver.
[Illustration: BUDS OF WAYFARING TREE.]
The soft silky buds of the willow, and especially those of the low
growing sallow which are gathered as “palm” for church decoration, are
amongst the welcome signs of early spring. The sallow has its male
blossoms on one tree, but not far away we shall find the female tree
bearing the flowers which will eventually produce the seeds. We may
therefore seek for three kinds of buds, those which produce the flowers
on each tree, and the others which will clothe the tree with leaves
when the blossoms are over.
This chapter shows us how much there is to instruct the student of
nature during the winter as well as the summer months.
I have but indicated a very few out of the many lines of study which
may be taken up; one could write essay after essay upon the growth of
a single hedgerow, but all I can hope to do in simple chapters of this
kind is to throw out hints and indications, and trust that my young
readers may find their interest sufficiently excited by what they have
read, to lead them on to fuller, deeper study of each point touched
upon.
Nature is an inexhaustible storehouse of wonders, and the further we
explore, the more our eyes are opened to see the vistas that lie before
us, branching out in various directions.
This special path of botanical study is one that, more or less, can be
pursued at intervals, as opportunity may offer through life, and as it
adds much pleasure to leisure hours, I specially commend it to my young
readers.
Specimens to be obtained and compared with the descriptions in this
chapter:—Search for buds in summer; plane-tree buds; Japanese maples;
terminal and axillary buds; observe shape and outline of trees; buds
of coniferous trees; fir cone; fir-tree that has lost its leading
shoot; pollard willow, and other trees, buds on marsh tway-blade, and
viviparous fern; buds on underground stems; suckers from wall-fruit
trees; dormant buds or knobs on tree-stems; bulbils on lily, dentaria
and allium; horse-chestnut terminal bud; observe leading shoot of
horse-chestnut in early summer; flower and leaf buds on beech; various
flower-buds; Oriental poppy; tulip-tree buds; various leaf-buds
unfolding; colouring of Japanese maple, lime, and sycamore buds;
whitebeam; variegated vine; purple hazel; mountain ash; spray of beech
buds; ash buds; _Picea nobilis glauca_; willow and sallow, male and
female flower buds and leaf buds; bamboo.
CHAPTER VI
_FLOWERS_
“Your voiceless lips, O flowers, are living preachers;
Each cup a pulpit, every leaf a book
Supplying to the fancy numerous teachers
From loneliest nook.”
+Horace Smith.+
CHAPTER VI
FLOWERS
Instead of looking at flowers as bright and beautiful objects made to
be a source of continual delight in our daily lives, though such they
truly are, we will rather now, for purposes of study, consider them as
the means by which the plant carries out the purpose of its creation,
namely, to perfect its seed and thus perpetuate its species.
In the life-history of shrubs, trees, and plants we find this is their
one aim, and that everything else is subservient to it.
The stamens and pistil being of essential importance in forming the
seed, we find them placed for safety in the centre of the flower;
folded round them are the petals or coloured parts of the flower, and
outside these again are the green sepals, or leaves of the calyx.
These two sets of enfolding leaves are called “floral envelopes,”
because they fold over and protect the central organs, the stamens and
the pistil.
We will select a buttercup as a type, and taking it to pieces we will
try to learn the names and uses of its various parts.
The outside is a greenish-yellow cup which is called the calyx.
The divisions of this little green cup are called sepals, and their
office is to protect the five bright yellow leaves within, which are
called petals when we speak of them singly, but, taken all together,
form the corolla.
In the buttercups the petals are all separate, but if we look at a
primrose we shall see that the corolla is in one piece, united in a
tube; so also is the calyx.
The botanical term for a corolla thus formed is _gamopetalous_, a long
word but easily understood when we know that _gamos_ means united; a
flower with petals in one instead of many divisions is more easily
referred to by this word than if we had each time to express it by a
sentence.
[Illustration: PRIMROSE.]
Gathering a newly-opened flower, we can see at a glance that the sepals
are placed quite below the central green organs of the flower, and
that they are in no way influenced by the petals; we also see that
the petals are entirely separate from the other parts of the flower,
and we learn, as the result of our examination, that the parts of the
buttercup are _free_. To express this botanically we prefix the word
“poly” to the words sepals and petals, and so we get _polysepalous_,
meaning that the sepals are quite free and distinct, and _polypetalous_
referring to the same condition of the petals.
Now, having removed the petals and sepals, we can proceed to study the
other parts of the flower.
First we find a great number of little yellowish stalks tipped with
tiny pouches; these are the stamens, and in the little pouches
(anthers) the yellow powder termed pollen is developed. We will
carefully take away these stamens, and note in so doing that they are
all distinct and all sprung below the green central part. Like the
sepals and petals, we find the stamens are free and uninfluenced by the
other parts. If we again compare this with a primrose-flower we shall
find a difference; the stamens of the primrose spring from the petals
and are therefore called _epipetalous_ (_epi_ upon, a petal). Again in
the sweet-pea or scarlet runner we find the stalks of the stamens are
all joined together. We now have left upon the flower-stalk the little
central green parts previously mentioned; there are quite a number
of them; each one is distinct from its neighbour and is free. These
bodies are known as carpels, they are large at one end and taper to a
curved point at the other, the broad end being attached to the stem.
Collectively these carpels constitute the _pistil_, and because the
carpels are apart and free it is said to be _apocarpous_.
The flower of the little woodsorrel (_Oxalis acetosella_) will help us
to understand better the arrangement of the carpels. If we take away
the sepals, petals and stamens, we shall have only the carpels left,
and these are five in number. They are in the same position as those
of the buttercup, but they are not separate, they are joined by their
inner surfaces. We can plainly see that this is the case, since each
carpel is distinctly outlined and there are five little tapering ends
(stigmas). The pistil in this case is said to be _syncarpous_.
Names are given to express some quality, and they often draw our
attention to interesting facts about the plant’s mode of growth or the
place where it is found; for instance, the pretty blue nemophila is so
called from _nemos_, a grove, and _philo_, I love, because it delights
in shady places.
Geranium is derived from _geranos_, a crane, because the fruit of some
of the species resemble the beak of that bird.
Some plants are named after famous botanists, as _Linnæa_ after Linnæus.
Others derive their names from their mode of growth, as stone-crop,
which is called sedum, from _sedo_, I sit, the plant having scarcely
any stalk, and sitting, as it were, on walls and rocks.
These instances will show that it is well worth while to study names
and learn their meanings, as they often throw so much light upon the
history of a plant.
In the flowers of bulbous plants we find that the calyx and petal
leaves are frequently alike in colour and texture; in that case the
three sepals and three petals, of which they usually consist, are
spoken of as a perianth.
In looking at the brilliant colouring of a flower we should hardly
imagine that the petals have to some extent the nature of leaves, and
under certain conditions may be changed to the green colour and form of
ordinary leaves.
In very wet seasons we may sometimes find rose-buds with the sepals of
the calyx developed into perfect green leaves. The floral envelopes
therefore possess the nature of true leaves.
[Illustration: POINSETTIA.]
The brilliant scarlet so-called flowers of the poinsettia are really
coloured bracts, the true flower being the small inconspicuous
blossom in the centre.
In the chapter on leaves we saw that bracts are those small
imperfectly-shaped leaves in the axils of which flowers are placed.
They are usually green, but may be also brilliantly tinted as in the
mauve-coloured Bougainvillia, the bright violet spikes of the _Salvia
Hormineum_, and also pure white as in the spathe of the arum.
By special cultivation flowers can be made double, for excess of
nourishment will cause the plant to multiply its petals. Instead of
the five pink petals of the wild rose we find one of our garden roses
bearing as many as eighty or a hundred petals.
Double flowers but rarely produce seeds, because the stamens and pistil
have been turned into petals, and as there is no need to attract
insects for fertilising purposes, there is no secretion of honey, and
therefore we scarcely ever see honey-bees in double flowers; they are
wise enough to know that their visits to them would be in vain.
In composite flowers such as asters and sunflowers the change, when
they are double, occurs in several ways.
The centre may become filled with florets similar to those in the
outside ring, or the florets in the middle may become larger or of a
different colour.
These various changes may be readily observed in the cultivated
chrysanthemums, in which every form and variety of flowering can be
traced.
When the pollen has reached the pistil the flower begins to fade,
because its end has been attained; nature, however, has such variety
in even the smallest of her operations that the passing away of a
flower is accomplished in different ways. In the primrose the corolla
withers and drops to the ground. The flower of the spiderwort, one
of our common garden plants, becomes pulpy as it fades, in this way
resembling the pineapple plant, the flower of which eventually becomes
the luscious succulent fruit.
The poppy is proverbial for its fleeting petals, which scarcely last
more than a few hours, a passing wind soon scattering them far and wide.
“Pleasures are like poppies spread,
You seize the flower, its bloom is shed!
Or like the snow-fall in the river,
A moment white—then melts for ever.” (+Burns.+)
Some flowers, as the hydrangea, have persistent petals, which simply
lose their brilliant tints and become tough and brown.
[Illustration: WINTER CHERRY.]
The calyx of the physalis or winter cherry continues to grow after the
flowers are fertilised until the round balloon-like bag is formed in
which the fruit is enclosed.
We will now examine the parts of a flower separately, beginning with
the calyx.
In the buttercup the calyx consists of one whorl or ring of five sepals.
In the strawberry there are two whorls of sepals, and in the cotton
plant there are three whorls forming its green calyx.
There are also variations in the mode of flower expansion.
As a poppy-bud opens it detaches its calyx from the stem, and the
sepals fall off (the calyx is therefore called caducous, a term which
means ready to drop off).
Many flowers retain the calyx until the petals wither and it falls off
with them. It is then called a deciduous calyx.
Others again have a permanent calyx, so that when, as in the primrose,
the corolla withers and drops off, the sepals close over the
seed-vessel and protect it until the seeds are matured; this would be
called botanically a persistent calyx.
The best way to learn the names of the different parts of a flower is
to pull it carefully to pieces and arrange the separate organs on a
thin card. They can be tacked on to the card with a stitch or two of
fine thread, and when the lesson is over, if the card is placed between
sheets of blotting-paper under a weight, the flower dissections will
dry and be useful for reference later on.
Each separate part of the flower should have its name neatly written
beneath it, so that when a good many different flowers have been thus
dissected they may be compared and the variations in form and position
duly noted.
[Illustration: WALLFLOWER.]
A wallflower will be a good subject for our dissection.
At the back of the petals we first take off the calyx, which consists
of four divisions called sepals. We then pull off the four yellow
petals, and as they are placed in the form of a cross it shows
that this plant is a crucifer, or cross-bearer, one of a very large
natural order, _Cruciferæ_,[16] none of which are poisonous and very
many are useful food-plants, such as cabbage, turnip, watercress, and
cauliflower. Now there remain six stamens—four long and two shorter
ones; these last rise outside of and alternate with two nectaries or
honey-glands.
[16] All cross-shaped flowers do not, however, belong to this order.
The stems of the stamens are called filaments, from _filum_, a thread;
and the upper part, containing yellow powder, is called the anther, the
proper name for the powder itself being pollen.
In the centre of the flower is the pistil, the lower part of which is
the ovary, the part of a flower which contains the ovules, and is so
named from _ovum_, an egg.
The stem part of the pistil is called the style and the top of it is
the stigma.
Such simple words as I have given must be learned, else we cannot
understand botanical descriptions, and if this page is studied whilst
we have the flowers in our hands it will not be difficult to identify
each separate organ; when these are once arranged on a card with the
name of each part written beneath it, we shall have attained some very
useful information ready for future study.
In the buttercup flower all the five petals are the same size and
shape; therefore, like hundreds of other evenly-formed blossoms, it
would be described as “regular”; but if we take a sweet-pea, balsam, or
monkshood-flower and examine its separate petals, we shall find they
vary very much in form, and they are known as “irregular” flowers.
The sweet-pea is a type of a large order of plants producing what
are called butterfly-shaped flowers, and _papilio_ being Latin for
a butterfly, they are therefore called papilionaceous flowers. If
we learn clearly about the various parts of such a flower we shall
henceforth be able to recognise it at a glance.
In the sweet-pea we find a broad petal at the back of the flower which
is called the standard, beneath it are the two side petals called
wings, and within them is the keel, so named because it is shaped like
the bottom of a ship. Within the keel lie the stamens and pistil—the
most important parts of the flower, and to protect them from injury the
standard is so formed as to catch the wind like a sail and turn the
blossom round so that this broad petal shelters the keel from rain.
[Illustration: SWEET-PEA.]
In our next ramble out of doors it will be well to try and gather all
the specimens we can find of this order of plants. If it be in summer
or autumn we shall soon collect a handful of these butterfly-shaped
flowers.
On a common we shall find broom, furze, restharrow, vetches, tares,
trefoil, clover, saintfoin, and other plants. In the garden and
greenhouse we shall see many more species belonging to this class.
Having shown the difference between a regular and irregular flower, we
will now proceed to notice how irregularity is caused.
If we pull off one of the buttercup petals and look at the base of it,
we shall see a small pouch which contains honey; it is called a nectary
or honey gland, and the position of this gland has much to do with the
shape of the flower.
As each petal of the buttercup has a nectary at its base it follows
that, all the petals being the same size and shape, the flower is
perfectly regular—like a small golden cup. Now in other flowers we
shall find the nectary very large and confined to one petal or sepal
only, and this results in the flower having an irregular shape. Gather
a violet, examine and compare the petals; four of them will be found
to be nearly alike, but the lower petal is much larger because it has
grown into a tube (called a spur) to secrete honey, and I need hardly
say that the honey is intended to attract the bees so that the flower
may be enabled to produce fertile seed. The enlargement of the lower
petal gives the flower an irregular shape, and the same thing happens
in the monkshood and many other flowers, where both the petals and
sepals are thrown out of shape to form nectaries. In the orchid family
this influence may be traced to a wonderful degree. The contrivances
for insuring the fertilisation of their flowers are so many and various
that books of the greatest interest have been written on that subject
alone.
In the flowers we have hitherto noticed, both stamens and pistils are
found, the petals are coloured, honey-glands exist, and some specimens
also possess a powerful scent.
Such flowers are obviously very attractive to insects, and on that
account they are called by modern botanists, entomophilous, which long
word means that they are beloved by insects.
In sharp contrast to these gay and conspicuous flowers we may observe
the very simple catkins of the birch, _Betula alba_. If we examine a
twig of this tree in spring, we shall find two very distinct kinds of
flowers (or catkins, as tree-blossoms ought properly to be called),
one a stiff green spike standing upright, and the other longer and of
yellowish colour, always to be found hanging down.
The former consists of a number of scales arranged on a central stem,
and in the axil of each scale is the little pistil, with its pointed
and divided stigmas. This catkin, later on, becomes the fruit of the
tree, and sheds out with every passing breeze its little winged fruits,
which are carried far and wide and often sow themselves in rocky
crevices, and appear able to grow and flourish with only a modicum of
soil.
[Illustration:
_Natural Size._ _Magnified._
BIRCH FRUIT.]
The pendulous catkin is very soft and loose, and on the inner surface
of its scales we find the stamens, which in due time will shed from
their anthers the fertilising pollen. Here then we see flowers which
are not so attractive to insects, flowers in which the stamens and
pistils are separated and developed in different catkins, and such
flowers are termed monœcious, from _monos_, single, and _oikos_, a
house.
The most interesting feature of these tree-blossoms is their
fertilisation by the wind; the slightest puff of air liberates little
clouds of pollen from the loose swinging anthers; these pollen grains
become entangled in the upright catkins bearing the pistils, and the
future seed thus becomes fruitful. There are many trees and plants
which are thus fertilised by the agency of the wind, and they are
termed by botanists _anemophilous_, from the Greek words _anemos_,
wind, and _philos_, beloved by.
In the common bryony of the hedges, we get another example of a green
inconspicuous flower. Gather a few sprays of this in early summer,
taking care to keep the specimens of each plant separate. Take up one
specimen and you will find each flower has a small green calyx, a
minute corolla, and five little stamens; not one pistil can we find on
the spray.
The flowers on the next spray look very similar, but in them there are
no stamens, the centre of each flower being occupied by a small pistil,
and thus we learn that there are two distinct sexes in the bryony
plant, the one bearing only staminate flowers, and the other producing
those bearing only pistils. Such plants are termed diœcious, from _di_,
two, and _oikos_, a house.
[Illustration: WILD ARUM.]
One of the earliest spring flowers is the arum of the hedges, known
to village children as “lords and ladies.” Accustomed as we are to
bright-hued flowers if in our gardens and fields, it is somewhat
difficult to recognise that the pale-green sheath of the arum is a
flower at all. It consists of a beautifully-folded spathe or bract,
curving over at the top, and if we remove that we find a central stalk
bearing a number of little naked flowers, arranged in the order shown
in the plate.
First, below the club-like apex, a few hairs tending downwards,
then the anthers containing pollen, and below these the pistils with
protruding stigmas. The whole stalk is termed a spadix.
The outer green spathe forms a kind of prison, into which flies are
enticed by the somewhat fetid odour which is exhaled by the flower. The
flies easily creep in past the circle of hairs, which, as they point
downwards, do not prevent their entrance, but, once in, these hairs are
like a _chevaux-de-frise_, and hinder the escape of the insects. The
flies in all probability carry upon their wings pollen from some other
arum flower, and in their efforts to escape they brush off this pollen
upon the stigmas, which thus become fertilised. When this has taken
place the stigmas throw out a sweet juice upon which the insects feed;
the anthers now shed out their pollen, with which the flies become
covered; the hairs meanwhile have withered, and thus the flies, having
done their appointed work in fertilising the flower, are free to crawl
out and perform the same office for some neighbouring plant.
We have not space to do more than allude to certain plants, whose
flowers never open and are self-fertilised. The common violet, for
instance produces, in addition to its well-known fragrant flowers,
certain inconspicuous blossoms, hidden under the leaves and close to
the root, very seldom noticed by any but botanists, and known to them
as cleistogamic flowers; these are fertile, and always produce seed.
Other such plants are the woodsorrel and sundews.
It is interesting to observe the various ways in which flowers are
protected from browsing animals, snails, and caterpillars by thorns,
spines, prickles, and spiny bracts. The teasel secretes water in the
bracts around its stem, which prevents ants from ascending to the
flowers, and in many plants we may see quantities of small insects
caught by a sticky gum exuded from the leaves and twigs.
Many delicate plants entirely alter the position of their flowers in
order to protect them from rain. On a sunny day the wood-anemone holds
its little snowy cup so as to receive the full sunlight, but on a damp
day every blossom is closed and held downwards. We may observe this in
the poppy, the blue-anemone, and nearly all composite flowers.
These are merely hints scattered over a wide field of study, which
some readers may like to follow out.
Objects to collect and examine:—Buttercup flowers, seed-vessel of
wild-geranium, stonecrop growing on walls, flowers of bulbous plants,
flowers of poinsettia, bougainvillia, salvia hormineum, arum. Examine
various chrysanthemum flowers, sunflowers, asters and woodsorrel.
Difference between hydrangea and poppy flowers, winter cherry
(physalis); prepare flower dissections. Examine various cruciferous
flowers and pea-shaped flowers, regular and irregular flowers, birch
catkins, wild arum flowers, cleistogamous flowers, protection of
flowers, position of flowers.
CHAPTER VII
_POLLINATION_
“When summer shines,
The bee transports the fertilising meal
From flower to flower, and even the breathing air
Wafts the rich prize to its appointed use.”
+Cowper.+
CHAPTER VII
POLLINATION
We now come to the consideration of the real function of the flower
of a plant. In whatever form it is developed, whether as a gay and
fragrant blossom, in a dull foul-smelling structure like the arum, or
as a green inconspicuous little floret like the grass, its main office
is to reproduce itself by the formation of seed. We will first glance
at some of the wonderful agencies that actively help in this work.
There are at least three distinct processes necessary for the complete
formation of a perfect seed, and we must, I fear, persuade ourselves
to learn some of the long words by which botanists speak of these
processes. They are known as pollination, fertilisation, and the
growth of the ovule. There is so much to be said about the first
subject, that I must leave the two latter for a succeeding chapter.
Before seed can be formed it is necessary that the powder contained
in the anthers, which is called pollen, should be transferred from
those anthers to the stigma or upper part of the pistil, and this
transference is called pollination. If we examine a tulip or, better
still, a buttercup, we find the anthers and stigmas so near together
that the transfer of the dust-like pollen to the sticky-looking
stigmas can easily take place. This would be called an instance of
self-pollination, but although cases of this kind do occur in nature,
they are not at all common. As a rule, in order to ensure what is
called cross-pollination, the transfer of the pollen of one flower to
the stigma of another, many wonderful and interesting arrangements
exist even in some of our commonest flowers.
Cross-pollination must be the case in such plants as dog’s mercury,
because we find in a colony of these plants—so frequently seen by the
roadside—that some plants have flowers with stamens only, and others
containing only pistils. Again, in the hazel we may see how impossible
it is for self-pollination to take place, as, if we examine the
pistils, we find that they consist of scales bearing stamens and pollen
only, whilst somewhere close by, on the same stem, hangs the pretty
little red flower which possesses the pistil and forked stigma. If seed
is to be formed in either of these flowers and in many others similarly
arranged, then the pollen of one flower must be transferred to the
stigma of the other.
[Illustration: PRIMROSE.]
There are interesting facts to be learned about the common primrose.
When we examine a little bunch of these flowers we find quite half of
them are what children call pin-eyed, meaning that the stigma, which
is at the end of a long pistil, is like the head of a pin in the throat
of the primrose.
Looking at the sketch, we see at once that self-pollination is hindered
by the fact that the anthers in this flower being at the bottom of the
tube, the pollen they contain must be transferred by some direct agency
before it can come in contact with any stigma. Now let us examine the
other flowers in our primrose nosegay; we find the stamens in these are
placed in the mouth of the tube, and the pistil is quite short and low
down in position. At first sight it appears as if the pollen would fall
directly upon the pistil, since the stamens are above that organ, but
this is not exactly what happens; the pollen of this particular form of
flower is shed before the stigma is mature, so that when it has reached
maturity the pollen is all gone.
The arrangement of nature is as follows. An insect attracted by the
sweet-smelling bank of primroses will visit the flowers, thrusting
its proboscis down a pin-eyed flower until in so doing its head has
been dusted with the pollen of the stamens; then withdrawing from that
flower the insect visits another near by, possibly one with a short
pistil; the pollen on its head is now rubbed off and falls upon the
stigma below and pollinates it, for that is the term used when this act
takes place.
[Illustration: MAIDEN PINK.]
The pretty maiden-pink will help us still more clearly to understand
how cross-pollination is promoted in flowers containing both stamens
and pistils. Select a flower that has just opened, the petals of which
are spreading and fringed, whilst from the centre of the flower a
cluster of stamens projects with the pollen mature and easily shaken
out of the anther lobes; the pistil is concealed in the long tube, and
in this stage there is no sign of stigma. In a short time, however, if
we examine the flower again, we shall find the stamens have shrivelled
up, and in their place a forked stigma appears, as shown in the sketch.
Here again it is obvious that the fact of the stamens ripening first
and expending their energy before the pistil is ripe must mean, that
in order to secure seed the pollen from some younger flower must
be transferred, probably also by insect agency. It will give fresh
interest to our garden rambles if we remember that the bees and flies
we see hovering over the flowers are not only collecting honey or
feasting upon it, but are also performing a very important office for
the benefit of the plants they are visiting.
We may now proceed to notice the various agencies for the conveyance of
pollen between flowers.
These agencies are water, wind, insects and birds.
In an earlier chapter I gave an account of the _Vallisneria spiralis_,
which will serve as a type of a water-pollinated flower.
Those pollinated by wind are, as I have said in a previous chapter,
called anemophilous (_anemos_, wind, and _philos_, loving). They are
usually of small size and inconspicuous character, with very little or
no scent, and devoid of colour; these are characteristics that are not
always associated in the same species; thus in the hazel, which is a
wind-pollinated flower, we find a bright yellow catkin (so well known
to children as lambs’ tails) and a small but bright red pistil.
Let us notice, however, how wonderfully these plants are adapted
for this method of pollination; the stamens are usually hanging,
and the pollen, produced in great quantities, is easily set free by
the slightest breath of wind. The stigma of the hazel, of different
grasses and of sedges are both forked and plumed, so that pollen grains
floating in the air are readily intercepted.
The firs and pines are excellent examples of wind-pollinated trees. I
remember once possessing a ripe male cone of the _Araucaria imbricata_,
and ascertaining that it contained as much as a wine-glassful of
pollen. Speaking about this fact to the gardener at the Pinetum
at Dropmore, I was shown how this fertilising dust from the great
Araucaria (which was planted there in 1830) was carried by the wind
for an amazing distance to a female tree on the other side of the
garden, pollinating its cones so that they produced fertile seeds.
In some of the Canadian pine forests, the trees shed forth such
quantities of pollen in the flowering season that the ground becomes
perfectly yellow. The early settlers, being unable to account for the
strange phenomenon in any other way, ascribed it to showers of sulphur
descending from the clouds. Even in our own country the foliage and
undergrowth in the neighbourhood of fir woods is often thickly coated
with the yellow dust falling from the male catkins of the trees; the
structure of the pollen grains is such that they float very buoyantly,
each grain being provided with two air bladders. I may mention in
passing that this apparently wasted pollen affords a rich feast to
endless species of bees and flies, and is in many cases stored up by
them as food for their young grubs. The various adaptations for wind
pollination will perhaps be better understood if we glance at the
attractions which flowers offer to birds and insects.
Colour serves to render flowers attractive to insects, and to make them
conspicuous; the bracts, petals, and sepals of flowers are usually of
some light or dark colour quite distinct from the green tone of the
foliage.
It has been ascertained also that plants which are pollinated by
night-flying moths generally have white or light-yellow flowers so as
to be easily seen in twilight.
One of the most interesting of these night-pollinated flowers is
_Silene nutans_, the Nottingham catchfly. In the daytime the five
narrow petals are curled up and look dead and withered, but as night
comes on they change their position, and the flower has the expanded
shape of an alpine pink. In this open condition it is visited by the
moths which, flying from one flower to another, transfer the pollen,
and thus accomplish at night what more frequently occurs in the
sunlight; at daybreak the petals roll up once more, and one would again
suppose the flower to be dead; but no, it will continue to open at
nightfall until some moth finally succeeds in pollinating its blossom.
A small species of moth[17] visits this catchfly in order to deposit
its eggs; these, by means of a very long ovipositor, it places in the
ovary, and in that somewhat inflated cavity they produce microscopic
caterpillars which find shelter and nutriment in the strange nest.
When the caterpillars arrive at maturity they escape by biting a hole
in the wall of the capsule, and creeping out, they seek for a suitable
place in which to turn to chrysalides.
[Illustration: ARISTOLOCHIA.]
[17] _Dianthræcia albimacula._
Scentless flowers usually have some equivalent form of attraction, such
as honey, brilliant colour pollen in abundance, or the grouping of a
number of small florets, in order to secure a conspicuous effect as in
the ox-eye daisy, or hedge parsley.
Strong and varied odours are great helps to ensure pollination by
insects. The bee-tribe and moths and butterflies are specially
attracted by the sweet scents of roses, violets, carnations, and
sweet-peas, and the powerful odour emitted by such flowers as the
evening primrose, tobacco, and night-flowering rocket as evening comes
on tends to guide the nocturnal moths to these and similar flowers. An
odour may, of course, be pleasant to an insect which to us would be
simply intolerable. The arum of the hedges, and those curious plants,
the aristolochias and stapelias, all emit scents of the most fœtid
description, as we think, but flies, on the contrary, are attracted by
thousands, and hold apparently joyous revels in the blossoms which
they are pollinating by their frequent visits.
[Illustration: STAPELIA.]
A little care and patience in watching the visits of insects to
different flowers will soon be rewarded by a perception of the tastes
and likings of insect life, and we shall gradually learn to expect to
see certain insects on the flowers they specially frequent.
[Illustration: HYPERICUM.]
I would call attention to the interesting fact that if one agency
fails to effect pollination, another is adopted in order to attain the
desired end. Thus, when the flowers of the common bartsia first open,
they are visited by insects; but, in the later stages of flowering,
the pollen is blown out by the wind, and the neighbouring stigmas thus
become pollinated. We see in the arrangement of the flower of the St.
John’s wort (_Hypericum_) a perfect type of this provision against any
possible failure of pollination. The stigma is surrounded by groups of
stamens of unequal length; those in the centre nearest to the stigma
are as long as the style itself, whilst those on the outside are short,
and these shed their pollen first, whilst those in close contact with
the stigma shed their contents last. Thus we find that if insects fail
to effect cross-pollination by means of the short and early opened
stamens, it is secured by means of the longer stamens whose anthers are
in close contact with the stigma. Again, when we stand under a sycamore
tree, we may see that the green tassel-like flowers are having their
pollen dispersed both by wind and bees.
We cannot draw hard-and-fast lines in nature, for although a special
end may be kept in view, the various means and adaptations by which
it is attained are a continual source of admiration and wonder to the
reverent student of nature.
We have already seen that there are all kinds of devices by which the
pollen of one flower may be made sure to reach the stigma of another;
but, if by any means this crossing fails, if the weather is such that
insects are scarce, or other conditions cause failure, then, in the
case of many flowers, most curious contrivances are provided to secure
seed by self-pollination. Truly this is one of the most beautiful of
God’s wonders in floral construction. One of the gems of my own flower
garden is a lovely little Japanese toad-lily (_Tricyrtis hirta_). In
this flower there are three styles which stand well above the stamens;
the points of the styles are bent over as in the plate, and the
stigmatic surface grows mature before the anthers shed their pollen;
if, however, no insect visits the flowers, pollination is effected in
the following way. The styles bend down and place their forked points
in direct contact with the open anther-lobes (as shown in drawing),
the style assuming almost the form of a semicircle. This is done very
deliberately, for it is often fully a week before the act is complete.
[Illustration: TOAD-LILY.
_Stigma and Stamen._]
Pollination is effected in tropical countries not only by insects of
many kinds, but by the lovely tribes of humming-birds which abound in
those regions. Their slender, curved beaks are specially adapted to
penetrate the honey-laden flowers with long-tubed blossoms, which could
only be pollinated by some such agency.
Those who are within reach of the Natural History Museum at South
Kensington may there see a gallery filled with exquisite specimens of
humming-birds, arranged in cases, and some of the birds are shown as
they appear in life, hovering over tropical flowers, drawing honey
from their hanging blossoms, and performing the useful office of
transferring the pollen from one flower to another, thus ensuring the
fertilisation of the seed.
I might go on multiplying examples of the various methods by which seed
is rendered fertile, but perhaps enough has been said to show what
hidden force exists in flowers to enable them to attain the end for
which they mainly exist, namely, the perpetuation of their species by
means of seed.
Specimens to be obtained and compared with the descriptions in this
chapter:—Buttercup flower, dog’s mercury, hazel catkins, primrose
flowers, male blossoms of pine trees in June, Nottingham catchfly,
ox-eye daisy, bartsia, St. John’s wort flowers, and Japanese toad-lily.
CHAPTER VIII
_FERTILISATION_
“The men
Whom Nature’s works can charm, with God Himself
Hold converse.”
+Akenside.+
CHAPTER VIII
FERTILISATION
Having now considered some of the many wonderful arrangements by which
the pollen of plants is dispersed, we will endeavour by tracing the
course of the pollen-grains after they reach the stigma, to learn what
is meant by the term “fertilisation of the ovules.” These are the
minute specks contained in the ovary which are to become seeds, and by
means of which the plant will eventually reproduce itself.
To the naked eye the yellow pollen we see on the anthers of flowers
appears as small grains; but, when magnified, these grains are seen to
be singularly beautiful, each little sphere having on its surface a
chequered network and delicately sculptured patterns.
The forms, too, are as varied as the ornamentation.
Some plants have triangular grains, some oval-shaped and others
many-sided.
[Illustration: POLLEN-GRAINS.
1 _Morina._
2 _Cobea._
3 _Convolvulus._
4 _Dianthus._
5 _Pinus._
6 _Albucca._
7 _Buphthalmum._
]
I have given a few examples, and would specially call attention to the
pollen-grains of the Pinus tribe (fir-trees), to which I alluded in the
last chapter. These are remarkably buoyant, owing to the two little
bladders with which they are furnished.
[Illustration: WHITE-LILY PISTIL.]
[Illustration: SECTION OF PISTIL.]
Now we are going to watch this yellow dust performing its appointed
office in the central organ of a flower. In order to do so we will take
a white garden lily, and remove the petals, sepals, and stamens,
leaving only the pistil, which, as shown in the drawing, consists of
three parts, the club-like stigma, a very long style, and its base the
ovary, which contains three cavities. In these last we see a number
of small, colourless spore-like bodies termed ovules (from _ovum_, an
egg), each consisting of an outer coat, and a mass of cells in the
centre called the _nucellus_.
[Illustration: POLLEN TUBE.]
An opening exists at one end of each ovule called the micropyle
(meaning a little gate or entrance), and this opening leads down
into the middle of the nucellus, where lies what we may call the
life-principle, but what is known in botany as the embryo-sac.
We need the aid of a microscope to enable us to see how the pollen
exerts its influence upon the ovules.
If we place a drop of very weak sugar and water upon a slip of grass,
and sprinkle over it some pollen grains of the common white lily, then
allowing the slide to remain for a few hours in a dark place, it will
be fit for our purpose.
When placed in the microscope we shall observe that many of the
grains will have thrown out long thread-like tubes, and this is just
what happens when pollen falls upon the viscid stigma of the lily.
Referring to the section of a lily pistil we see that a pollen grain
has rested on the stigma, and, excited into growth by the sweetish
fluid which holds it there, it sends down a slender tube through the
centre of the pistil, which is lined with a very delicate loose tissue
of cells filled with starch, oils and food-materials. The pollen-tube
is stimulated and fed by this nourishment stored up in the conducting
tissue, and on it goes until, passing through the micropyle, it enters
the embryo-sac of one of the ovules, adheres to it, and renders it
fertile.
Only one grain is shown in the drawing for the sake of clearness, but
of course each ovule is sought out and fertilised by a pollen-tube.
With infinite variation this process takes place in every flower,
so that even the commonest weed affords evidence of the marvellous
provisions made by an All-Wise Creator for the preservation of species.
The time occupied by the passage of the pollen-tube varies
considerably. In the fir tribe it takes nearly twelve months, in the
hazel-nut and orchis it requires several weeks, whilst in many other
plants the whole process is completed in a few hours.
One of the first results of fertilisation is a rapid withering of
the style and flower; the great end of the flowering period has been
attained, and so without further expense of energy the bright petals
die away.
At the same time other external changes take place, which are obvious
to every observer of nature. The lower end of the pistil, known as the
ovary, begins its second growth, and in a short time swells into a
large structure, the shape of which varies much in different species
of plants. Finally, the ovary changes colour and develops other
characteristics quite different from its former conditions. These
characters have reference to the distribution of its seeds, and in
our chapter on fruits we shall learn something about the interesting
botanical significance of the various hard and soft fruits, and see how
they all arise from fertilisation.
Take, for example, the flower of an apple immediately after
fertilisation is effected. The petals fall off, the styles shrivel up
and the ovary rapidly enlarges; the tube of the calyx becomes fleshy,
and finally the well-formed apple is produced. The change, however,
does not end here; in this stage of development the little apple
is bitter and is charged with a vegetable acid. As the fruit grows
on, however, this acid changes into sweet juice varying in flavour
according to the species of apple.
Now let us examine the interior of the ovary and see what changes have
arisen as a consequence of fertilisation.
The egg cell which has received the pollen grain becomes filled with an
embryo, whilst the thin delicate coat of the ovule develops into strong
seed-coats.
The embryo is the first germ of the young plant that is to be. It is
a tiny speck indeed in its beginning, but deeply interesting to us
when we realise that, because it possesses life, it will grow on and
on, and result, according to its species, either in a plant but a few
inches in height, or in a grand forest-tree which may give shelter to
man and animals for hundreds of years.
The naked eye can scarcely trace any indications of form in the embryo,
but when dissected and examined with a lens it is seen to consist of a
tiny plant, root, stem and leaves (cotyledons).
The size of the embryo in comparison with the other part of the seed is
a point which should be observed.
As the embryo develops it absorbs the special nutrient or reserve
tissue that exists in all ovules; a bean embryo, for example, rapidly
absorbs all the nucellus of the ovule, so that at length the seed-coat
contains nothing but the embryo, the two cotyledons of which are thick
and filled with stores of food for the first growth of the seed.
I would advise students to plant a few broad beans in a little damp
cocoa fibre, and carefully watch their growth. It is advisable to
dissect these beans successively at different stages, so as to watch
the development of the radicle (root) and plumule (young leaf-bud).
Place the seed in what position we may, the radicle will always find
its way down into the earth, while the plumule obeys its vegetable
instinct, and rises into the air. The embryo of the castor-oil bean
and that of the cocoa-nut do not, however, use up all the nutritive
matter in the ovule as the broad bean does, so that when the seed is
ripe we find inside it, not only the embryo, but also a quantity of
cheesy matter known as _albumen_, and seeds of this kind are hence
called _albuminous_, whilst peas, beans and hazel-nuts are classed as
_ex-albuminous_ (without albumen).
[Illustration: SECTION OF COCOA-NUT.]
An interesting development consequent upon fertilisation is a growth
which occurs in some plants from the base of the ovule. The pretty red
coverings of the seeds of the spindle-tree, and the bright berry-like
structure on the seeds of the yew-tree are examples of this growth,
which is known botanically as an aril (from _arillus_, a wrapper). In
the willows this aril is a very lovely covering of silky hairs, these
serve to float the seeds on the atmosphere at every puff of wind.
[Illustration: SPINDLE-TREE.]
The pretty lace-like covering on the nutmeg is another example of an
aril, better known to us in the form of the fragrant spice called mace.
The style, which in most plants dies as soon as the ovules are
fertilised, is in other cases persistent, as in the hedge-climber
called travellers’ joy. The white, feathery-looking seeds owe their
special character to the persisting styles, which, after fertilisation,
grow into the bunches of fluffy seeds, which hang in profusion on
hedges in the country.
[Illustration: NUTMEG AND MACE.]
[Illustration: CLEMATIS OR TRAVELLERS’ JOY.]
I will conclude this chapter with a reference to a change of quite a
different character. Not unfrequently, fertilisation results in the
suppression of certain chambers in the ovary, and in the consequent
failure of the development of the ovules.
A cross-section of a young oak ovary shows a three-chambered structure,
each cavity containing two ovules, so that the ovary in this stage
contains six ovules in three chambers. Soon after the act of
fertilisation, one of the fertilised ovules takes the lead in growth,
starves the other five ovules, and, as it grows, pushes the partitions
of the other chambers aside, and gradually fills up the whole interior,
converting it into a one-celled structure. This change happens also in
the birch; its two-chambered ovary becomes one; and in the lime, though
at first it has a many-chambered ovary, yet in the ripened fruit there
is rarely more than one to be found.
In a few plants, changes of quite an opposite character take place.
In the ovary of the datura,[18] for instance, we find two cells;
after fertilisation, two false or spurious partitions are developed,
dividing the original two-celled structure into four parts, and as a
consequence we get a four-chambered fruit. The same change takes place
in some of the pea family.
[18] Thorn-apple.
Specimens to be observed:—Examine pollen grains, with lens or
microscope, dissect white lily, flower-pollen on glass slide. Observe
changes in growing apple, plant broad beans, castor-oil seeds, and
maize; examine spindle-tree berries (_euonymus_), yew-tree berries,
willow seeds, nutmeg, and mace; travellers’ joy (clematis), section of
oak ovary in the pistillate flower. Examine birch catkins and lime-tree
flowers. Datura seed-vessel.
CHAPTER IX
_FRUIT_
“Here, as I steal along the sunny wall,
Where Autumn basks, with fruit empurpled deep,
My pleasing theme continual prompts my thought;
Presents the downy peach; the shining plum;
The ruddy, fragrant nectarine; and dark,
Beneath his ample leaf, the luscious fig.
The vine, too, here her curling tendrils shoots,
Hangs out her clusters, glowing to the south,
And scarcely wishes for a warmer sky.”
+James Thomson.+
CHAPTER IX
FRUIT
If we are shown a collection of delicious apples, pears, grapes,
peaches and cherries, we form a very appreciative opinion of the use
and function of fruit, but that opinion is somewhat modified when we
are shown a basket of poppy-heads, acorns, the light downy seeds of the
thistle, the small dry carpels of the buttercup or the winged fruits
of the maple. We usually connect the term fruit with some luscious
product of the vinery or kitchen-garden, and we may include as such
the brightly-coloured berries of the hawthorn and wild rose, which are
so conspicuous on trees and hedges in autumn; but if we examine the
subject botanically we shall have to widen our ordinary conception of
the term.
There is probably no part of a plant so difficult to understand as
its fruit, and this difficulty is due to those many changes which I
described in my last chapter. A very general definition of fruit is
that it consists of the ripened ovary, and this will be found to be
correct in a great number of cases, but this term is not exactly wide
enough to express the general formation of all fruit. In some cases
it is composed of the ripened ovary with the parts of the stalk or
the original flower, enlarged or incorporated in the structure of the
fruit, but in other specimens we find the ovary, although present, very
little enlarged, and playing but a minor part in the ultimate character
of the mature fruit.
No fact seems so emphatic to the observant botanist as that which
upsets his artificial rules and classifications of plants and the parts
of plants. We say, for instance, that fruit is the ripened ovary, and
yet directly we leave our books and go out to study botany in the
fields and woods, we find a large group of fruits perfectly innocent of
any such structure. The firs and pines have no organ of this kind, and
yet their fruits are most important and extremely interesting. Scarcely
any part of a plant varies so much in different species as the fruit
does. Although leaves may be found of every size and shape, they still
have some general similarity of form, but we hasten to observe what
an immense contrast there is between the huge _Musa_ fruit (banana)
and that of the oak (acorn), although the former is, compared to the
latter, but a poor weakly plant.
Again, let us note the difference between the cocoa-nut palm fruit, a
nut, which with its outer husk is almost as large as a peck measure,
and that of the St. John’s wort or any other of our native wild flowers.
These differences in size have their counterparts in other directions.
We generally think of fruits as being soft, luscious, and pleasant to
the taste. Many fruits of delightful colour and texture are, however,
bitter as gall, and possess highly noxious qualities. I well remember
gathering a plateful of rich purple berries from a plant I discovered
in one of my childish rambles and carrying them home as a great prize;
I was not a little disappointed when I learned that they were the
poisonous fruits of the deadly nightshade; their deceitful resemblance
to plums, as well as the berries of the woody nightshade to red
currants, make these two of our most dangerous native plants.
As offering very distinct contrasts to the above, we may note the dry
membranous fruits of many of our forest-trees, the hard nuts of the
hazel and walnut and the leathery husk of the chestnut. Again, the
shape of fruits is wonderfully diversified. We have round and oval
apples, plums, and gooseberries; the linear seed-pods of the cabbage,
cauliflower, wallflower, peas and beans, and other plants in endless
varieties of forms.
There are contrasts again in the smooth surface of some fruits and the
hairy coats of others where the roughness is due to hooks, prickles
and other contrivances. How different, too, is the airy pappus of the
dandelion to those heavy fruits which drop like stones and are to be
found lying exactly beneath the branches where they have ripened.
These differences in external form are multiplied when we examine fruit
more minutely. We shall then find a useful dividing line in the manner
in which fruits allow their seeds to escape. In one large division the
fruit when perfectly ripe splits open and allows the seed to fall out;
such fruits are termed dehiscent (from _dehisco_, I gape). In the other
division the fruit remains closed, and the substance of it must decay
before the seeds can escape and grow; these are classed as indehiscent
(I gape not). Before referring to a few examples of each division we
will endeavour to distinguish clearly the various parts of a fruit and
learn their proper botanical names.
We must be careful not to confound the seed and the coats of the ovary;
the latter is termed the pericarp (_peri_, around, _karpos_, a fruit).
In some fruits this pericarp is developed into distinct coats, or
layers. In a peach, for instance, the outer coat is rough and hairy,
this is called the epicarp (1) (_epi_, upon, _karpos_, a fruit); the
middle coat is the succulent delicious fruit, and is known as the
mesocarp (2) (_mesos_, middle, _karpos_, fruit), whilst the inner coat
is the hard stone, or endocarp (3) (_endon_, within, _karpos_, fruit),
and inside it lies the kernel, or true seed. As a type of a dehiscent
fruit we may select a pea-pod; here we get no division of the coats
into distinct parts, the pericarp is dry and tough, and when perfectly
ripe it bursts open, and allows the seeds to escape.
[Illustration: SECTION OF PEACH.]
It would be very interesting to make a collection of various
seed-vessels, and note the immense variety of ways in which the seeds
find their way out of the dry capsules. A poppy-head, campanula and
antirrhinum sprays, henbane, columbine, stramonium, and many other
plants afford good examples.
[Illustration: POPPY CAPSULE.]
The woody pear is the hard fruit of a New Holland plant which splits
open to release the seeds. The horse-chestnut is a conspicuous instance
of a dehiscing fruit, the rough prickly part is the pericarp, and
when the fruit is mature this splits open and allows the two large
chestnuts (seeds) to escape. In the sweet-chestnut we get an altogether
different structure. If we pick up one of its spiny burrs, we hold in
our hand what is called in botany an involucre (from _involucrum_,
a cover), that is, a number of bracts which have grown together and
formed an outer case to the fruit. The acorn-cup is an involucre, and
we may find other good examples in composite flowers and those of the
umbelliferæ. The small green whorl in which a daisy-flower is set is,
therefore, not a calyx, but an involucre consisting of minute bracts
grown together. The true fruit of the sweet-chestnut is enclosed in a
mass of spiny bracts, and thus differs entirely from the pericarp of
the horse-chestnut; if we wish to speak of it correctly we must call
it either a cupule or involucre. We will now select a few examples of
fruits that are indehiscent.
[Illustration: WOODY PEAR.]
On the outside of an orange we find the yellow coat of the pericarp,
next to it is the white mesocarp, and inside is the juicy endocarp,[19]
in which the seeds are embedded. When an orange falls to the ground
these different coats simply decay, and the seeds are aided in their
efforts to grow by the succulent flesh of the fruit, which affords them
moisture and nutriment. The hazel-nut is a fruit of another texture
altogether. The hard shell is the pericarp, and the one or two seeds
within it must remain enclosed there until the shell decays and the
kernels can germinate and become new plants.
[19] Strictly speaking, the endocarp of the orange is a thin membrane,
and the pulp grows from it and fills up the ovary cavities.
In the currant, gooseberry, and date we find examples of indehiscent
fruits with a sweet fleshy pericarp. In the date there is only one seed
in each fruit, and a curious thin endocarp can be observed enveloping
the solitary seed. Many allied species, as well as the date, possess
this sweet pericarp, which must decay in order to liberate the seeds,
and in the case of succulent fruits the process is frequently assisted
by the fruit-eating birds.
It may be well to draw attention to the very simple kind of fruit
possessed by the buttercup and other similar plants. It is a dry
membranous pericarp, and inside one seed exists free from the pericarp;
this remains closed, like other forms of the indehiscent types, and
technically this fruit is known as an achene (from _achanes_, not
gaping), and it is well named, as it remains closed until decay enables
the growing radicle to break through the pericarp and enter the ground.
The curious after-development of the strawberry fruit is worth a little
careful study.
This flower is known as apocarpous (_apo_, apart, _karpos_, fruit),
consisting of a number of distinct ovaries each with one ovule; these
ovaries when ripe are exactly like the achenes of the buttercup, but
they are developed upon a receptacle which, when fertilisation has
taken place, begins to dilate and swell, with the result that the
little achenes are gradually scattered over the surface of a large
fleshy receptacle which, as it nears its time of perfection, becomes
of a most tempting crimson colour. The little seed-like dots we notice
on the strawberry are distinct and perfect fruits embedded in a sweet
succulent floral receptacle. Thus we find that the strawberry, speaking
botanically, is not a berry, but a collection of achenes, the term
“berry” being usually restricted to such fruits as the currant and
gooseberry. For this reason the strawberry and the common fig are
sometimes termed spurious fruits, for in these the soft pulpy flesh is
really the receptacle and the little round so-called seeds are the true
fruit.
There is a very different formation in the pineapple, since this fruit
is the development of an entire spike of flowers; these in their early
stage are crowded together on the flower stalk, but as time goes on
they coalesce and fuse, with their ovaries, bracts, and receptacles,
into a succulent mass, the various parts of which can be well defined
if we cut a section through a pineapple before it is quite ripe.
This chapter may fittingly conclude with a brief reference to the
ultimate purpose of these varied forms and textures of fruit, for
that they each have their special work, and that there is a meaning
for every form, is a truism we may accept without doubt. The fruit is
in reality the storehouse for the seeds, the latter being the vital
part of the plant. If we review the life-history of a plant, first
its producing flowers, then the special and intricate processes of
pollination and fertilisation, and subsequently the growth of that
wonderful little part, the ovule, into a seed, and further if we
reflect that the whole strength of the plant has been concentrated on
producing that seed, we shall then comprehend the true significance of
fruit.
The seed is first stored up in the recesses of the ovary; clearly
then the ovary, which subsequently becomes the fruit (pericarp), is
intended to protect the seeds, and it is interesting to note some of
the various ways in which this protection is afforded. Take first the
soft and sweet fruits so plentiful in the autumn; this edible sweet
flesh is not developed until the seeds are quite ripe. All through the
period of growth and ripening the pericarp is hard or stringy or it
may be also sour or acid. This is especially true of hedgerow fruit,
such as crab-apples, sloes, and wild pears, texture and juice alike
affording complete protection.
Again, such fruit as the walnut and chestnut are protected by their
rough covering and hard shells, and many others have their outer coats
covered with prickles and spines for the same reason. The most extreme
case is perhaps that of _Mucuna pruriens_, a leguminous climber found
in the tropics; this has downy pods not unlike those of a sweet-pea,
and these pods are covered with brownish hairs which, if incautiously
touched, enter the pores of the skin and cause a most intolerable
irritation; a truly formidable protection this to the seed.
Let me now point out how the seed is protected in some of the pine
family (firs), where there is no pericarp. During the growth and
development of the pine seeds, the woody cone is rich in resin, and
should an enterprising nuthatch try to peck out the seeds, he finds his
beak covered with the resin and his effort baffled.
[Illustration: PINE-CONES.]
Protection is also afforded to the seed by the movements of fruit
after fertilisation, and of this the cyclamen flower affords a good
illustration. As soon as fertilisation has taken place the flower stalk
coils up like a watch-spring, and the seed-pod is thus placed safely
beneath the leaves to ripen.
In crevices of old walls we may often find that charming little
wilding, the ivy-leaved toad-flax; it has a highly intelligent method
of protecting its seeds. When the flower is fertilised its stalk bends
its point round to the wall, and places the tiny ovary in a cranny
of the brickwork to mature and ripen its seeds. These are but two
instances, out of hundreds, of plants whose fruits are protected by
what we call instinctive movements.
It is of essential importance to young seedlings that they should have
sufficient soil, light, and air, to ensure their healthy growth. To
begin life directly under the leaves of the parent plant is to court
failure and starvation, and so we find in the fruit that wonderful
provisions are made to ensure the dispersion of the seed when it
leaves the parent plant, and so endless are the contrivances for the
dispersion of fruits and seeds, that it will be needful to devote the
next chapter entirely to that subject.
Objects to collect and examine:—Compare various fruits, fir-cone,
banana, acorn, seeds, and berries, &c. Examine a peach and pea-pod.
Collect seed-vessels, horse-chestnut, sweet-chestnut, daisy-flower,
orange, hazel-nut, date-fruit, strawberry, pineapple.
Observe seed coverings, pine-cones, cyclamen stems after flowering,
seed capsules of ivy-leaved toad-flax in wall crevices.
CHAPTER X
_DISPERSION OF FRUITS AND SEEDS_
“Who gave the thistle’s feather’d seed its plumes,
That wing-like waft it on each gentle breeze
To sterile yet to it congenial soils,
Investing them with purple beauty, rife
With fragrant treasures for the wild bees’ store?”
+T. L. Meritt.+
CHAPTER X
DISPERSION OF FRUITS AND SEEDS
I purpose in this chapter to explain some of the many remarkable ways
in which plants are enabled to scatter their fruits and seeds. The
chief agencies which assist in carrying out this purpose are wind,
animals, birds, running water, and moisture in the atmosphere. We
shall find that many seeds are furnished with certain outgrowths and
peculiarities which are specially adapted to the action of these
agencies, with the result that such seeds are distributed far and wide.
We will first examine some of those fruits which are scattered by
animals; this end is generally attained by means of hooks and curved
spines on the outside of the fruit.
Perhaps one of the most remarkable instances of this class is the
seed-pod (or capsule) of the Martynias. During the visit of the Prince
of Wales to India, a panther killed in one of the shooting excursions
was found to have quantities of long-hooked seeds attached to his skin:
these must have been brushed from a plant of _Martynia proboscidea_,
which has sharp curved horns three or four inches long.
[Illustration: SEED-POD OF MARTYNIA.]
Another species called by the Italians _Testa di Quaglia_, or quail’s
head, sows itself in a similar manner by clinging to moving objects.
Many common hedgerow plants have their fruits armed with quite
formidable hooks, so that creeping or flying creatures may be made
unwittingly the means of distributing the fruits. The burdock is a
most persistent plant in this respect, each of its numerous fruits
being covered with long hooks which successfully retain their hold
of our clothing if we happen to brush past the plant when covered
with its troublesome burrs. Other examples are the rough seeds of
the forget-me-not, agrimony, enchanter’s nightshade—a great pest in
gardens—and all the bedstraw tribe.
These plants, we may observe, are low-growing and herbaceous, quite
distinct in the matter of position from the tall trees and shrubs which
depend upon the wind to scatter their seeds.
We are all familiar with the winged fruits of the sycamore; they are to
be seen in early autumn. The clusters are first of a pale green, and
then the seeds[20] often attain a flush of pale crimson which adds
much to the picturesque beauty of the tree. The equinoctial gales
separate the seeds from their stalks, and away they go far and wide,
borne up by the delicate membrane attached to the seed which catches
the wind, and is carried by it to a great distance from the parent
tree. In the same way the winged keys of the ash, being very light,
are borne by the autumn gales to strange habitats, so that the tree
may often be found growing on church towers, in ruins, and on crags
inaccessible to man.
[20] In botany the fruit of the sycamore, maple, ash, &c., is called a
_samara_, and is properly speaking a winged _achene_.
[Illustration:
_Natural Size._ _Magnified._
BIRCH SEED.]
The pinus tribe of trees have seeds with wings slightly twisted so
that, if we hold up a dry fir-cone, the seeds descend from it with a
whirling motion like small shuttlecocks.
The winds which blow strongly in mountainous places carry these seeds
before them, and are thus ever renewing the pine-forests by sowing
the products of their cones on bare tracts of land. The lightest of
all tree seeds is that of the birch; it is gifted with two wings or
membranes, so that it floats in the air before the lightest breeze,
and this may account for the wide distribution of the tree which has
been found growing from Mount Etna to Iceland and Greenland. I may give
an instance of a common which, twenty years ago, was covered only by
furze, broom, and brake-fern; about fourteen years since, a shower of
birch seed must have been strewn over the ground, and now it has become
a wood, shutting out the distant views and quite altering the character
of the landscape.
The wind again is the agency for the dispersion of the seeds of such
plants as the common groundsel; here it may not be uninteresting to
note the beautiful provision made in regard to the buoyancy of the
seeds. These winged structures which the wind so lightly blows into the
air must attain a certain altitude from which they can be successfully
launched, and therefore we find that a large class of low-growing
plants have their seeds furnished with accessories in the form of light
silky down or hairs.
[Illustration: PARACHUTE.]
[Illustration: DANDELION SEED.]
Most of the plants known as _compositæ_ have their seeds thus
feathered, and amongst them are those plagues of the farmer, the
thistle, dandelion, goat’s-beard and others. The dandelion may serve
as our example, and I would advise my readers to watch carefully the
variations of position in the flowering stems. Whilst the flower is
still fully expanded the stalk remains in an upright position so that
it is conspicuous and likely to attract the notice of insect visitors.
After the florets are fertilised it gradually lowers itself until it
lies on the ground under the leaves for a period of ten or twelve
days. During this time the seed-vessel matures and ripens, then the
stalk rises to the erect position once more, and the beautiful downy
globe expands into a soft fluffy ball of seeds hanging so loosely
that the first breeze carries them away, and their descent into the
ground is curiously provided for. Persons have sometimes alighted on
the earth from a balloon by means of a parachute, a machine which
closely resembles an open umbrella with a car at the lower end. Now
the dandelion seed descends in a similar manner, touching the ground
first with its lower end, the weight of the seed enabling it to drop
into some hole in the soil, and the spiny projections at the upper
end preventing the feathery part of the seed from dragging it out
again. The common goat’s-beard is perhaps the most beautiful English
example of fruit with a downy pappus. A single flower will produce a
sphere as large as a cricketball, and each seed is furnished with a
starlike crown of branched feathers which the wind can bear away to a
considerable distance.
[Illustration: GOAT’S BEARD.]
The handsome willow-herb, which adds so much colour and beauty to our
river banks, bears its seed in long, narrow pods, and these, when ripe,
split up into five segments which, curling back as they open, leave the
downy seeds free to be carried off by the passing breeze.
Bird agency in seed dispersion is a most interesting subject, and
one can but admire the wonderful way in which the services of winged
creatures are made available.
Succulent berries and sticky fruits are highly attractive to many kinds
of birds, and whilst they revel upon the sweet, soft flesh of the
berry, the seeds which they swallow with it are enabled to resist the
action of digestion by a hard covering which protects the kernel until
the shell shall decay and allow the seed to germinate. In this way I
find my garden in early spring quite thickly strewn with the seeds of
the Irish ivy, always a favourite food of the common wood-pigeon which
is so frequently to be heard cooing in my woods.
The seeds of aquatic plants often cling to the feathers of birds that
visit pieces of inland water, and are widely distributed by them in
their flight from one lake to another.
[Illustration: COCOS-DE-MER.]
Darwin has shown by careful experiment that the mud clinging to the
feet of various birds almost always contains seeds. A wounded partridge
had a ball of earth weighing six and a half ounces adhering to its
legs. From this earth Darwin reared no less than eighty-two separate
plants of five distinct species. Seas and rivers also do their part in
dispersing seeds. The huge nuts of the _Cocos-de-mer_ palm, which grows
only upon the Seychelles Islands, are often thrown upon very distant
shores. This nut is said to take ten years to come to perfection; it
is exceedingly hard, and sometimes weighs as much as forty pounds.
The common cocoa-nut is often found growing on the shores of coral
and other islands in the Pacific Ocean, and owes its position there
to the buoyant nature of the nut, which floats uninjured in the sea
until it finds a resting-place and a home on some atoll or island. In
this way the cocoa-palm has spread to such an extent that it is now
perhaps the only palm common to the western and eastern hemispheres.
West Indian seeds and fruits have even been thrown upon the Norwegian
coasts, and, but for the unsuitability of the climate, there is little
doubt that tropical trees and plants might sometimes be found growing
even so far north. It is obvious that the seeds of all vegetation on
the banks of rivers, small running streams and lakes, must be liable
to very wide distribution. Darwin made many interesting experiments as
to the length of time seeds could retain their vitality when floating
in fresh or salt water. Ripe hazel nuts germinated after being ninety
days in water. An asparagus plant with mature berries, when dried,
floated for eighty-five days, and the seeds afterwards grew vigorously.
Out of ninety-four plants experimented upon, eighteen floated for
more than a month and some for three months, their germinating power
not being destroyed. In quite a large number of species the plants
themselves possess the means necessary to distribute the seed. It is
true the distance traversed by each seed may not be great, but it is
sufficient to give the seed a new field of growth. This power varies in
different species. It is perhaps best defined as elastic force, and in
the majority of cases the seed is actually thrown away from the parent
plant by the expenditure of this force. The seed-pod is generally in
a state of tension, due to the gradual drying up of the tissues. Then
a puff of wind, a slight blow, or even a change in the atmospheric
condition of the air, gives the final impetus, causing the pod to
burst with such force that seeds are thrown out in all directions. The
fibro-vascular cords are often found crossing the pod in an oblique
direction, or even in a spiral manner, so that finally, as they
shorten through dryness, they act upon the walls of the legume and we
see the result in such dried pods as those of the sweet pea, broom, and
laburnum.
[Illustration: BROOM AND SWEET-PEA PODS.]
The pansy has a three-valved seed-pod, and as it dries the edges of
the valves press upon the polished, hard-shelled seeds and they are
squirted out with a jerk to a distance of several feet. I was once
greatly puzzled by a strange, crackling sound in my room, and after
a few minutes’ search I discovered it was caused by a fusillade of
pansy seeds striking against the sides of a small box in which I had
placed the capsules to ripen. It is worthy of notice that the capsule
hangs down to protect the seed-valves from rain; but when the seeds
are matured the capsule rises to an upright position so that they
may be projected far and wide. A conspicuous example of the elastic
force of which I have spoken is seen in the British balsam, _Impatiens
Noli-me-tangere_ (touch-me-not). When its seeds are mature, the valves
of the capsule curl up in a spiral form with such force as to project
both themselves and the seeds through the air many feet from the plant
dropping the seeds by the way. On a hot summer’s day one may hear the
dispersion of seeds! The furze and broom pods, the sweet peas, and
especially fir tree cones, make quite a loud report as they split and
scatter their contents. The tension causing these explosions is in some
cases brought about by the fluids inside the fruit. This is the case
with the squirting cucumber, which, when fully ripe, is so distended
with fluids that the slightest touch or movement is sufficient to
cause it to break away from its stalk, and then the whole contents are
ejected with great force, so that the seed is thrown some distance. The
extent of dispersion is very limited in those plants that are dependent
upon the varying moisture of the air. Such plants are usually furnished
with special awn-like[21] appendages; these are hygroscopic[22] in
their nature, and the difference in the amount of moisture in the air
lengthens and contracts these apparently moving organs. When the seeds
fall from an ear of barley they lie thickly strewn around the bottom
of the stem, and, were they to take root there, they must inevitably
choke each other; but each awn is thickly set with bristles, and as the
morning sun shortens and the evening dew lengthens the hair-like awn,
the prickles only allow the awn to move in one direction, and the seed
which is attached to it is slowly but surely drawn many inches away.
What is popularly called the dancing oat is another curious example
of this hygrometric property. If a dry seed (or oat) is placed for a
moment in water, and then laid on a smooth table, it will be seen to
wave its long horns as if they were the antennæ of an insect, and to
turn over and over until it has progressed some inches from the point
where it was first placed. In _Avena elator_ (the tall oat grass) and
_Stipa pinnata_ the awns are bent sharply just as they emerge from the
flowers, the part below the bend being like a corkscrew and highly
sensitive to moisture, relaxing and contracting according to the amount
of moisture in the air, with the result that the seed travels along the
ground. By the help of the long awn it can pass over small obstacles,
such as stones or clods, the movement resembling that of a lever.
[Illustration: STIPA PINNATA (FEATHER GRASS).]
[21] The beard of corn.
[22] Sensitive to moisture.
I must here guard my readers against those movements that are caused
by some insect larva. The so-called jumping bean imported from Mexico
is now so well known that it may be taken as a type of these curious
movements due, not to the seed itself, but to the efforts of an
imprisoned insect, the grub of a small moth which passes its larval
stage inside the hard-shelled seed of a kind of euphorbia.
In conclusion, we may glance at a small group of plants that develop
sticky glands for the purposes of dispersion.
That charming Alpine plant _Linnæa borealis_ has a pair of bracts
closely adherent to the fruit and these bracts are covered with
stalked glands of a sticky nature, so that when an animal, bird, or
even a passing moth brushes against the little fruits they stick to
the intruder and are thus borne away. Now it may perhaps occur to the
thoughtful reader that the Linnæa seed-vessel, being part of a growing
plant, would not readily break off with a slight touch, but it is
another instance of that consummate skill and arrangement that is so
apparent to the close observer. In the stalk of the little fruit there
is a special separating layer[23] (analogous to that of the falling
leaf which we noted in a previous chapter), and at this point the
fruit readily separates if the slightest pressure is brought to bear
upon it. This example is typical of what takes place in such plants as
_Salvia glutinosa_ and _Plumbago capensis_ and _Rosea_. As a contrast
to these various modes of dispersion I may mention those seed-vessels
which are actually buried by the plants themselves, such as the
ground-nut, ivy-leaved toad-flax, and others. We must bear in mind that
these plants usually have aerial flowers in addition to those matured
underground, and that these aerial flowers produce fruits which are
subject to dispersion. We may therefore conclude that the underground
seeds are to ensure the continuance of the plant when the ordinary
methods have perhaps partially failed. My readers may each autumn find
an endless source of wonder and interest in the thousands of differing
fruits and seed-vessels which may be obtained in any hedgerow and
field; and by careful observation they may yet learn many new facts and
be ever adding to their store of knowledge by gathering and comparing
the fruits and their dispersion, as shown in the types sketched in this
chapter.
[23] Called botanically an “absciss layer.”
Objects to collect and examine:—Fruits and seed-vessels of martynia,
burdock, forget-me-not, agrimony, enchanter’s nightshade, bedstraw,
samara of sycamore, ash-keys, pinus seeds, birch seeds, dandelion and
goat’s-beard seeds, pods of sweet-pea, broom, laburnum, and pansy.
Seed-vessels of balsam, wild oat, feather-grass, _Linnæa borealis_,
salvia, plumbago, ground-nut, and ivy-leaved toad-flax.
CHAPTER XI
_GERMINATION_
“O Source unseen of life and light,
Thy secrecy of silent might
If we in bondage know,
Our hearts, like seeds beneath the ground,
By silent force of life unbound,
Move upward from below.”
+T. T. Lynch+
CHAPTER XI
GERMINATION
Having considered the processes which lead up to the formation of seed,
we may now investigate the life-history of a seed and its various forms.
Like fruits, seeds differ much in their outward shape. In size alone
we find a great contrast between the dust-like seeds of the orchids
and the huge seeds of the cocoa-nut-palm, while between those two
extremes we may note every gradation of size. In other respects, also,
the seed offers no less variety of form and covering than the fruit,
such variations having relation to the particular mode of dispersion
and germination. The outer skin or coat of a seed, called the _testa_,
offers a very interesting field of study, and such seeds as the poppy
and _silene_ with beautiful network, the _bignonia_ and _pinus_ with
membraneous wings, the cotton-plant seed with long hairs, and the
_collomia_ with hairs that are resolved into mucilage when wetted, are
all worth special study. When a small portion of _collomia_ seed is
moistened and placed in a microscope one may see the rapid change being
effected; that which had been a hard dry atom suddenly throws out coils
of gum, like watch springs, and a novice is led to ask, “Is the thing
alive?” so full of motion does the object appear.
[Illustration: BIGNONIA SEED.]
We may regard a seed under various aspects. As a special means of
continuing the life of a plant, one of its modes of reproduction, as
a special means of tiding a plant over a season that would be fatal
to its life in its ordinary condition of leafage, in the seed we have
the germ of the future plant, a reproduction of its parent. This germ
or embryo is lethargic or hibernating like many animals which exist
throughout the winter in a dormant condition, yet still continue to be
living vital bodies waiting for some special influence to come into
play, and ready to resume all the activity of a growing organism.
The construction of a seed is simple; inside the coat or _testa_ we
find the embryo with or without a special supply of albumen; if the
seed is ex-albuminous, then we may expect to meet with thick, fleshy
seed-leaves especially stored with this substance. The embryo contains
all the essential parts of the plant, the root, stem, and leaves; the
root in the seed state is called the radicle, and is that part of the
embryo which usually points towards the micropyle; this radicle forms
one end of the first shoot which comes out of a seed, the other end
terminating in the stem or plumule. This first shoot is known by three
names—axis, _tigellum_, or hypocotyle. The _tigellum_ in many plants
gives rise to a special structure; thus in the cyclamen it forms the
tuber, and the greater part of the “roots” of radishes and turnips is
due to it. In other instances it is a mere collar forming a slightly
thickened surface between the base of the cotyledon and the radicle.
The _tigellum_ is in reality a centre of growth, as may easily be shown
by cutting off an inch of the upper part of a well-grown carrot and
placing the slice in a saucer of water; before long a crown of young
leaves will spring up and will continue to grow and flourish as long
as the plant food contained in the slice is sufficient to maintain the
leafage. In botanical language we have thus been growing carrot leaves
from this _tigellum_.
The embryo varies very much in the relative position of its parts.
Thus the embryo of the reed-mace is straight in the _tigellum_ of the
embedding albumen. In contrast to this is the curved embryo of the
deadly nightshade and the spiral embryo of the hop.
[Illustration: DOUBLE EMBRYO OF ORANGE.]
The seeds of the orange often contain two embryos, which is rather
a rare occurrence in the vegetable world. Before we can trace the
future of these parts we must attain a clear idea of the change the
seed undergoes when it germinates. In the whole of our studies our
attention has been drawn to no process so deeply interesting and yet
so mysterious as that of the breaking into life of the seed. There
are three conditions that promote the process of germination: warmth,
moisture, and air. When these three conditions are present and the
seed is healthy, growth begins, and its first stage is the absorption
by the seed of moisture; this, combined with warmth and the oxygen of
the air, sets up a change in the contents of the seed. We have already
seen that seeds are of a dry and starchy nature, and in this condition
they are insoluble and unfit to be active plant food. The change that
ensues results in this starchy matter being converted into sugar which
is soluble; then the parts of the embryo begin to unfold, first the
radicle and finally the plumule are developed. In this early stage
these parts live entirely upon the contents of the seed, just as a
young chick is developed and nourished upon the albumen of the egg.
The temperature requisite for germination varies according to the
species; those of us who possess gardens know to our cost at what a
low temperature such plants as chickweed, bittercress, groundsel,
and some of the speedwells grow; as long as the thermometer is above
freezing-point these troublesome weeds will make their appearance in
our flower borders. Sach’s experiments on germination tend to show that
wheat and barley begin to grow below five degrees centigrade, whilst
French beans and maize germinate at nine degrees centigrade.
Some plants start into growth very quickly. Garden cress, vegetable
marrows, and some grasses appear above ground a few days after they
are sown, whilst other seeds, enclosed in a hard, woody seed-case,
will require twelve months to germinate. This was the case with a
seed taken out of a cedar cone brought from Mount Lebanon; I vainly
watched for the young plant, and when a year had passed by the pot
was thrown aside on a rubbish heap. Shortly after I was passing by and
observed a fir-cotyledon growing on the heap, and this proved to be the
long-desired young cedar-plant.
Seeds have the power to retain their vitality for years, especially
those of the _Leguminosæ_, but I believe the stories of Egyptian mummy
wheat germinating are scarcely to be believed. A good object-lesson
upon this subject is furnished by a newly-made railway cutting; here
we may always find growing upon the freshly-turned soil quite a crop
of plants which have sprung from seeds that in the course of years
have become embedded in the earth, it may be at so great a depth as
to preclude the admission of air or prevent one of the necessary
conditions of germination. When, however, the underlayer of soil is
brought to the surface and exposed to light, air, and moisture, the
seeds are able to grow.
[Illustration: BROAD BEANS.]
To this we owe the richness of our railway-bank flora, and many a
rare plant may be discovered there which cannot be found elsewhere in
the neighbourhood. We will now in imagination conduct a few simple
experiments that we may learn something of the behaviour of seeds
during their early stages of growth. Each seed that we thus study may
be regarded by us as a type of many others. First, then, we will sow,
in a few pots, about a dozen broad beans; before doing so we may notice
on the seed the black stripe or ridge known as the _hilum_; this is the
scar showing where the seed was attached to the pod, and at one end of
it is the micropyle (_small gate_). If we remove the skin of the seed
we shall observe the two fleshy cotyledons or seed leaves, a tiny point
which is the rudimentary root, and, lying close to the inner face of
the cotyledon, the slightly curved plumule. After the beans had been
sown a few days and carefully watered, we may take up two or three for
examination. At first we may only see the radicle just emerging from
the little hole at the end of the _hilum_, but if we wait, say, eight
or nine days, we shall get a further development.
Before digging up our seed we will see if any others are peeping
through the soil. Yes, here is one, just an arched kind of shoot, no
leaves, only the bow of the arch pushing up the particles of the soil,
so that the point of the shoot is clearly still below the ground.
Now, taking up a seed we notice that the radicle has penetrated some
way down into the soil, and with a pocket lens we are able to see a
little higher than the tip of the root quite a crop of delicate little
root-hairs. The cotyledons are still enclosed in the tough skin, but
the upward growth of the _tigellum_ is acting on them like a lever,
and we can now plainly see that it is this _tigellum_ that, by its
upward growth, is penetrating the soil, and in so doing is drawing
the cotyledons from the seed coat. All this time the delicate plumule
is kept out of danger by the arched shape of the _tigellum_ and the
folding of the cotyledons. Leaving our seeds for a day or two longer
we find a further change. The plumule has been carried up beyond the
soil-level and has begun to expand into leafage. It is interesting
to note how the curved _tigellum_, pushing through the soil first,
effectually guards the plumule from injury arising from contact
with rough particles of earth; the cotyledons remain just below the
soil-level and we see that the _tigellum_ is thickening and forming
a distinct connecting branch between the new shoots and the fleshy
seed leaves; these latter are full of plant food, and the plumule is
supplied from this storehouse of nutriment until the first leaves are
formed and are able to decompose carbon-dioxide for the nourishment
of the plantlet. The seed-leaves in this case do not perform this
function, but act simply as storehouses.
Our next seed example will be the familiar mustard plant. These we may
sow in two lots, the first we only need to sprinkle upon some fine soil
and the second may be sown in a shallow drill and covered with fine
earth.
[Illustration: GROWING MUSTARD SEEDS.]
The first sowing will quickly germinate, and the movement of the
radicle which pushes out of the micropyle may be understood by
reference to the appended diagram. In it we see the white thread-like
radicle emerging from the seed coat; it turns very quickly towards
the ground and pushes directly into the soil. Here I must direct my
readers’ attention to one of those minute arrangements which, though
apparently insignificant enough if we fail to study the context, is
really an evidence of the infinite perfection, care, and wisdom of the
Creator in even such a tiny detail as the springing up of a mustard
seed. As the seed lies upon the ground, the lengthening radicle, while
it penetrates the ground, has a tendency to force the seed into the
air (as shown in the illustration), and were it allowed to do so the
seedling would soon shrivel up and die. This catastrophe is, however,
averted by the development upon the radicle of quite a crop of fine
white root-hairs; these adhere closely to the minute particles of the
soil, and are thus enabled to counteract the force exerted by the tip
of the radicle; the latter pushes through the ground without uplifting
the seed. This action can be watched and the growth of the root-hairs
observed by means of a pocket lens and by the exercise of that virtue,
most necessary for all young naturalists—patience.
Returning to the seeds that were sown under the soil, we find they
have germinated; the radicle is pushing downwards, and just above the
soil-level we may see the short curved _tigellum_. This very quickly
straightens itself, and then we observe that the cotyledons have been
drawn out of the seed-coats and are displayed as two green leaves,
which in a few days will be an inch or two above the ground, owing
to the growth of the _tigellum_. Here we get quite a departure from
the bean seed, whose cotyledons were _hypogean_ (under the earth),
those of the mustard being _epigean_ (upon the earth). There is also
another point of difference; the mustard cotyledons are green, they
contain chlorophyll corpuscles, have stomates, and so can perform
all the functions of the normal green leaf; thus they help at once
to feed the young plantlet by decomposing the carbon-dioxide of the
air and forming starch, whilst in contrast to this we learnt that the
seed-leaves of the bean were storehouses only. We are now sufficiently
acquainted with the functions of the seed to be able to appreciate the
variations of the _testa_, or seed-coat. In numerous instances the
spines, prickles, hairs, and other growths on the surface have, in
addition to their use in dispersing the seed, an essential purpose in
holding the seed in its rightful position. We will take cress as our
next example, since it may be regarded as a type of all smooth seeds.
Cress seed remains intact until water comes in contact with it; then it
becomes slimy by the liberation of a mucilaginous cement from the outer
coat layer; this is, of course, highly adhesive, and thus the seeds are
fixed firmly into the soil.
Another example is that of the little epiphyte (mentioned in our first
chapter), _Tillandsia usneoides_, or old man’s beard. When the seeds
leave the capsule they are furnished with silky hairs, which enable
the tiny little structures to float through the air; they soon come in
contact with the bark of trees, and then the little hairs cling to
the rough surface. In this position the seeds germinate, and are held
firmly in their place by the tightly-clasping silken strands.
[Illustration: BEECH COTYLEDONS.]
Hardly any pursuit is more delightful than the collecting and drying
of seedling trees; a ramble through the woods in early summer will
reveal many specimens under or near the outskirts of the foliage.
Under the beeches we shall soon light upon the nuts of last year
coming up through the moist, rotting soil, in the form of two broad,
green seed-leaves. As they often retain the dry, three-cornered
seed-husk upon them, we can easily see that they are young beeches;
otherwise, the cotyledon leaves being so unlike the perfect form, it
might be rather difficult to distinguish the species. These seedlings
have germinated somewhat like the bean seed, the radicle has grown
downward, and the curved _tigellum_, pushing upwards, has drawn the
cotyledons out of the seed-coat. We may notice with surprise through
how small an aperture the cotyledons have been pushed, and still they
are uninjured, a fact that is due to their being folded up like a fan
in the seed-husk. As soon as the _tigellum_ reaches light and air it
straightens out, and the flat seed leaves, which are at first of the
palest green, soon deepen in colour, and are working away preparing
food for the growth of the young plumule which springs up from between
the cotyledons, crowned with two perfect young beech-leaves. This
is all the baby-tree can do the first year. We can distinguish the
second-year seedlings by their woody stem, brown leaf-scales, and
silken-fringed young beech-leaves.
[Illustration: ACORN.]
We shall not find cotyledons on the young oak, horse-chestnut, or
sweet-chestnut seedlings, because these remain normally below the
ground (hypogean), forming a storehouse of nutriment for the young
tree. It is interesting to watch the growth of an acorn when placed in
damp moss in a saucer. After a few weeks the acorn will have absorbed
water, and the leathery seed-coat will burst at the pointed end;
through this rent the radicle will protrude, fibres will be found
growing upon the root, the _tigellum_ is thick, and just where the
stalks of the cotyledons are joined to it the plumule emerges as from
a sheath. The plumule is in no hurry to develop leaves; its first
growth is provided for by the rich supply of food within the acorn.
If, however, we look carefully at its little stem, we shall observe
upon its surface a few scattered scales, each with a rudimentary bud in
its axil. When the shoot has attained a height of three or four inches
it develops its first green leaf, and by the end of its first summer
about six will have been formed. A collection of these seedling trees,
carefully dried[24] and neatly arranged in a blank book, with the
English and Latin names to each, a note of the age of the seedling, the
spot where it was obtained, and the date, will in time form a pleasant
memento of forest rambles, and, probably, may lead to further studies
of a similar kind.
[Illustration: HORSE-CHESTNUT.]
[24] They merely need to be placed between sheets of blotting paper,
which should be dried daily and kept in a press or under a weight for a
few days until the specimens are fit to be placed in a book.
To make the collection complete there should be some seedlings of the
other great division of plants, namely, the plants with one seed-leaf
(monocotyledons). A few date-stones will supply these specimens; they
should be sown in moist earth and placed either in a greenhouse or on a
sunny window-ledge, where their growth can be watched.
Their germination is quite different from that of the other seeds we
have described, and if a number of seeds are sown the different stages
can be seen as in the accompanying figure.
One long cotyledon is pushed out from the seed, the free end is like
a sheath. The part nearest the seed forms a structure resembling a
rolled-up stalk; from the former roots are developed, whilst from
the rolled-up stalk or sheath grows the next formed leaf, and each
successive leaf is sheathed like its predecessor. This arrangement can
be well seen in young growing grasses which can be taken to pieces and
examined. I shall conclude this chapter with a brief reference to the
spores or so-called seeds of ferns and mosses.
[Illustration: YOUNG DATE-PALM.]
These are essentially different from the seeds that have formed
our study in the earlier part of this chapter, they do not contain
an embryo. Let us first notice fern-spores, which we shall find in
abundance at the back of maiden-hair and other fern fronds; they are
contained in little brown patches known as spore cases (_sporangium_,
from _spora_, a spore, and _aggeion_, a vessel). If we collect some
of these and sow them on some very fine damp earth, keeping it at the
same time shaded and warm, the spores will soon germinate. We shall
not find a radicle this time as the result of growth, but in its
stead a flat expansion of green tissue (prothallium, Gr. _protos_,
first, _thallos_, a branch) growing upon the earth like an exceedingly
delicate leaf. From the underside of this green film a few very fine
root-like hairs (rhizoids, Gr. _rhiza_, a root) are developed; very
soon with a microscope we shall be able to discern upon the surface of
this structure a few little projections. In one of these is developed
a flask-shaped mass of cells (archegonium, Gr. _archegonos_, first
of a race), in the other (antheridium, diminutive of Gr. _anthera_,
an anther) some minute bodies (antherozoides, Gr. _anthera_ and
_zooid_, a minute life) with tails; these escape from the covering and
wriggle about very much like tiny animalcules until finally they come
into contact with the flask-shaped opening before mentioned. These
tailed structures are something like pollen grains in their function,
only they differ from pollen grains, which are passive, by being
endowed with the power of motion; the result of their fusion with the
flask-like body is to fertilise the germ cell (oospore, Gr. _oon_,
an egg) in that structure, and from the germ cell so fertilised is
developed an embryo from which at once springs the young fern plant.
The first leaf grows from the upper part of the embryo and from the
lower part is developed the “foot,” a little connecting-link between
the green prothallus and the baby fern which serves to nurse the little
plant until two or more leaves have been produced; the roots also grow
from the same part of the embryo. I imagine that fern spores could
be grown and watched through all their various stages even by those
of my readers who dwell in towns, as a bell glass would maintain the
requisite dampness and shelter the young ferns from smoky air.
Lastly I will describe an even simpler form of spore development.
At any season of the year we may find the capsule fruit of mosses
(Calyptra, Gr. _Kaluptra_, a veil), a very common one being the hair
moss (Polytrichum, Gr. _Polutrichos_, having much hair), borne upon
long wiry stalks. Inside the capsule we shall find a large quantity
of small greenish bodies; these are the spores, which of course fall
out when the spore-case is blown by the wind, and being light are
easily carried away and at length find a resting-place in some damp
nook or shady bank. In such a place they find the conditions necessary
for their germination, which is not unlike the same process in other
seeds and spores we have studied. The result is very simple. A fine,
silky, thread-like body (protonema, Gr. _protos_, first, and _nema_,
a thread) is developed; when this has attained a fair size, a little
moss plant begins to grow upon its surface exactly as we see a bud grow
upon a tree-branch, and it is upon this moss plant that the organs of
reproduction are produced. We have now come to the end of our study of
seeds.
An endless source of interest to the student of nature is opened up to
view by carefully observing the beginning of all vegetable life, and
the seed or spore of the commonest weed or fern will teach us lessons
that should ever make us mindful of the wonderful mystery of life and
its genesis.
Objects to collect and examine:—Poppy, silene, and collomia seeds.
Examine _tigellum_ of cyclamen, radish, and carrot. Sow broad beans,
mustard, and cress seed. Collect seedling trees. Sow date-stones.
Examine fern and moss spores.
CHAPTER XII
_THE PHYSIOLOGY OF PLANTS_
“Lo! on each seed, within its tender rind,
Life’s golden threads in endless circles wind;
Maze within maze the lucid webs are roll’d,
And, as they burst, the living flames unfold.”
+Erasmus Darwin+, _The Botanic Garden_.
CHAPTER XII
THE PHYSIOLOGY OF PLANTS
In this chapter I will endeavour to present to my readers a concise
view of the nature and method of the various processes that go on
continually in the growing plant.
These processes were incidentally referred to in our examination of the
character of the various organs of the plant. Thus, in dealing with the
root, we spoke of its physiology so far as concerned the absorption of
water by its root-hairs. In the leaf, we touched upon the correlation
between the shape and arrangement of the leaf tissues and the part
the leaf plays in the economy of the plant. The physiology of the
reproductive organs, again, we briefly explained in connection with
their natural history.
In order to arrange our studies systematically, we may divide the
physiology or function of plants into groups, and, taking each group
separately study their effect on the plant.
We may then divide the functions of plants into
Nutrition,
Assimilation, and
Reproduction.
The first teaches us how a plant feeds and what it feeds upon; the
second, how the food is prepared by the plant so as to enable it to
use this food for growth and to store some of it away for future use.
The third group deals with the various means adopted by plants for
multiplying and increasing the species.
Plants, like animals, must _feed_ and _breathe_ in order to live; the
food of plants, however, differs from that of animals in being more
simple and elementary.
Plant food is of two kinds, water and gas. Water is an actual necessity
to the plant, both as a direct food and as a medium to convey inorganic
food. If we burn some wood to a white ash and then analyse it, six
inorganic elements will always be found—potassium, magnesium, calcium,
iron, phosphorus, and sulphur. These substances have been proved by
experimental water-culture[25] to be indispensable to plant-life;
others are found in larger or smaller quantities, but they are not,
judging by experimental tests, essential to plant life. These inorganic
elements do not enter the plant as such, but in the form of salts
dissolved in water; the phosphorus and sulphur as phosphates and
sulphates. Exactly how these salts and other elements are absorbed will
be best learnt from a simple experiment.
[25] Testing the effect of plant food by water-culture is carried out
in the following manner. Six large jars are filled with distilled
water. In No. 1 all the six elements above mentioned are placed in
small quantities, so as to form a weak solution. In No. 2 only five of
them are added to the water, and in each succeeding jar one element
is left out. A seedling plant which has been germinated on damp sand
is suspended in each jar in such a manner that the leaves are in the
air and the roots in the water without the seed touching the liquid.
The growth of the young plants is carefully observed, and the result
is found to be that No. 1 will grow and flourish, finding all its
needful food in the water, whilst the rest of the seedlings will show
plainly by their feeble and starved condition that, the food elements
being absent, they cannot build up their stems and leaves, and must
eventually perish.
We must first provide a large glass jar three parts full of clear
water. Then a lamp chimney, to the bottom of which a piece of membrane
(which any butcher will supply) has been affixed, should be partly
filled with water coloured by sulphate of copper, and then suspended in
the glass jar. Through a cork fitted to the top of the lamp chimney a
long tube should be inserted. The fluid in the lamp-glass will be seen
to rise in the tube shortly after the experiment is made, and the clean
water in the large jar will become slightly coloured.
[Illustration: TRANSFUSION DIAGRAM.]
This experiment teaches us that liquids have the power of passing
through a membrane; this power is known as diffusion, or _osmosis_.
Further, we notice that the clear fluid passes into the coloured water
more rapidly than the heavy coloured water passes out.
Now the fine _root hairs_ of a growing plant are _membranes_, having
the same property as the membrane we placed on the lamp shade; inside
the root hairs there exists heavy dense cell sap, outside are the films
of hygroscopic water containing (dissolved) inorganic salts, and this
water passes in through the membrane of the root, whilst a very little
of the cell sap passes out into the soil, the quantity passing in being
greatly in excess of that which escapes.
When once the crude water of the soil is inside, it is soon passed
along to the stem and leaves by the pressure of more water coming in,
and by what is called _capillary power_, this power we may easily see
if we dip a fine tube into water, when at once the water will rise up
some distance into the tube. I have pointed out that plant food is
gaseous as well as aqueous.
Oxygen is absorbed by the root very freely from the soil, and,
therefore, farmers and gardeners frequently plough and stir the soil
of fields and gardens so that the roots may obtain a supply of this
needful gas.
Let us now endeavour to see how the gaseous food is taken into the
plant. In order to do so we must remember that the gases necessary
for plant food form part of the air we breathe; this air is made up of
two-thirds nitrogen, one-third oxygen, with a small and varying, but
always present, quantity of carbon-dioxide, and of these the latter is
the most essential to the life of plants.
We have learnt in our study of the leaf how it, by the aid of the green
chlorophyll granules, and under the influence of sunlight, absorbs
this carbon-dioxide and effects certain changes in it. One of the most
essential elements in the growth of plants is _nitrogen_; this we
have just seen constitutes two-thirds of the air we breathe, but the
plant is unable to make use of it in this free form; that is to say,
although the leaf can freely absorb carbon-dioxide it cannot absorb
nitrogen; it has to be taken in by the roots of ordinary plants in the
form of nitrates, that is, in conjunction with some other element.
There is, however, an important exception to this rule; for what are
called the insectivorous plants have the power to absorb nitrogen under
certain conditions. These will be explained in the succeeding chapter.
We can now summarise the processes of nutrition. The roots absorb
water containing earthy salts as well as oxygen gas. The leaves absorb
gaseous food in the form of carbon-dioxide, and I may add sometimes
water vapour. There are two simple experiments that my readers can
make which will prove these statements, and will give them a greater
interest in the somewhat dry details of vegetable physiology. Our first
experiment to show the absorptive power of roots is taken from Sir
Joseph Hooker’s Primer on Botany.
“Take up three plants of the buttercup carefully by the roots; leave
one (No. 1) on the table; place another (No. 2) with its roots in
water; hang the third (No. 3) upside down over a tumbler of water with
a few of the leaves in the water, but the root exposed. In due time No.
1 will have faded; No. 2 will be quite fresh; No. 3 will have the parts
not in the water faded. No. 1 shows that water contained in the plant
has evaporated from its surface; No. 2 that the water has been absorbed
by the root and conveyed to the leaves; No. 3 that the immersed leaves
have not supplied the other portions of the plant with water.”
The second function, assimilation, depends upon several processes
that together go to make up the work of digestion and preparing plant
food. These processes are transpiration, respiration, and evolution
of oxygen; the latter process is associated with the feeding of the
leaf—that is, the absorption of carbon-dioxide. This compound gas
is under the influence of sunlight, and by the agency of the green
colouring granules, decomposed into carbon-monoxide and oxygen; the
latter is eliminated, whilst the carbon and a part of the oxygen is
retained, and with the absorbed water is converted into material that
the plant can use for the purpose of increasing its structure.
By a very simple experiment we can prove the escape of oxygen from the
foliage of plants. A few sprays of such leaves as laurustinus, bay,
arbor vitæ, and maiden-hair fern should be tied firmly to a piece of
stone. We should have ready a soup-plate, a glass shade, and a tub
full of fresh spring water (one large enough to allow the shade to be
held upright under the water). When all is ready, place the bunch of
leaves and stone in the glass shade held horizontally, and gradually
sink it under the water till the shade is quite full; place the
soup-plate at the open end where the shade is, and slowly raise the
glass until it is upright, and then it can be lifted out and placed on
a table in a window where the sun or bright light can reach it. The
bubbles of oxygen will soon begin to form along all the edges of the
leaves and the jewelled effect of the bouquet will be very curious and
beautiful. It is hardly needful to say the stone is simply required to
keep the group in an upright position. By the following day there will
be a large bubble of oxygen collected in the upper part of the shade,
eliminated from the leaves by the aid of chlorophyll and sunlight.
These changes resulting in assimilation are always in correlation with
the process known as _transpiration_. The root is continually taking in
fluids charged with inorganic salts; these are by the water conveyed
to the leaves by means of the network of veins, which we know by the
term fibro-vascular bundles. These, as we may see in skeleton leaves,
traverse the entire substance of the leaves where the salts are used up
in the constructive work of the plant. The water is not all wanted;
part of it passes off in the form of vapour. Transpiration, then, is
the passing off of this water.
[Illustration: SKELETON LEAF.]
We can easily see this process going on if we place a few tropæolum
leaves in a cool tumbler, and then expose the tumbler to sunlight.
In a short time the sides of the glass will show a film of moisture
due to the transpiration of the leaves. This process takes place more
freely in a warm temperature than in cool conditions; consequently, in
hot weather there is rapid transpiration, and as the water is parted
with more cell sap passes into the leaves and stems, and so the plant
is kept cool. We can now see the great use of the little pores known
as _Stomates_; these are found mainly on the under surface, and it is
principally through these pores that the leaf transpires.
We must now carefully note the fact that all growing parts of the
plant take up oxygen and give off carbon-dioxide. This power which is
common to all life is known as _respiration_. It is a process that
cannot be observed in daylight in green plants because this respiration
is feeble, and also because the opposite power of assimilation is
so strong that the action of breathing is obscured. In the absence
of sunlight, however, it can be observed, as also it may be traced
in connection with parts of the plant other than the green leaves.
Seeds, for example, during their earlier growth (germination) give off
carbon-dioxide freely by respiration. This we can prove for ourselves
by taking a large glass jar holding about two or three quarts; fill
this about half full of beans that have been well soaked in water so
as to swell them and induce them to commence germination. Close the
jar with a tight fitting cork; after six or seven hours the presence
of carbon-dioxide may be easily seen. Have ready a small phial of
clear lime water, and with a piece of twine let this down into the jar
without spilling its contents; allow it to remain there some minutes,
keeping at the same time the top closed with a handkerchief. We shall
see that the clear lime water will after a short time become cloudy
or milky; this is due to the carbon-dioxide, liberated by the seeds,
forming chalk with the calcium of the lime water, the chalk being
insoluble and easily seen. Now take out the phial and let it stand,
well covered, when the chalk in the form of a fine precipitate will
be seen at the bottom of the phial. If desired, a second experiment
can be made with the same jar by lowering into it a lighted taper; we
shall find it will go out owing to the presence of the carbon-dioxide;
as this gas does not support combustion our lighted taper is quickly
extinguished.
We can see from these experiments that respiration goes on in the
growing plant and that this process is independent of chlorophyll. It
is an essential part of the life of all plants, and my readers who may
perhaps wonder why it is that two such opposite processes as I have
described are both carried on in the plant must remember that in the
main the feeding process which depends on sunlight and the presence
of chlorophyll is carried on in the _daytime_, whilst respiration is
practically counteracted in the daytime by the vigorous intake of
carbon-dioxide. At night when the rays of light cease and no longer
enable the plant to feed, the respiration is evident. Briefly, we
learn that _in light_ the plant gains in weight, whilst _in darkness_
(by respiration) it loses. The green plant can only construct growing
material out of simple substances in light, having no power to do so in
the dark.
Heat is just as needful to plant-life; it must be above freezing point,
and a somewhat high temperature is necessary to set in motion all those
chemical processes that I have briefly described.
At a low temperature the work of assimilation and other processes
are arrested; on the other hand, a rise in temperature increases the
activity of these processes.
We now come to the third function called reproduction. We have seen
in connection with the food of plants how they convert inorganic
material into organic. This one fact is significant of the great office
of plant-life in nature; animal-life could not exist without its
help. Plant-life may be said to prepare the food of animal-life, and
retain that balance of gases in the atmosphere necessary to healthy
respiration. How important then it is that all kinds of herbs, trees
and plants should multiply and be fruitful, life of any sort is of
limited duration, and subject to all the vicissitudes of accident,
constitution, and climate, and so we find that plants have been endowed
with wonderful powers of reproduction in order that the earth may be
constantly clothed with vegetation, necessary for the life of man and
all animal nature.
By reproduction I want my readers to clearly understand the power
possessed by the individual plant to multiply its kind or species; and
this power is carried into effect in a variety of ways in different
species. These various methods of reproduction then will occupy the
concluding pages of this chapter. The protoplasm (or life principle)
of any individual plant is endowed with the power of giving rise to an
entirely new individual. This is accomplished in one of two ways. In
the first by cells forming a part of the plant, but yet not specially
modified for the purpose of reproduction. This mode of increase
is known as vegetative reproduction. We will illustrate it by two
examples widely apart. Many lowly plants like protococcus (the bright
green substance which so beautifully colours tree trunks in moist
situations) and yeast, are formed of one cell only, and when such cells
attain their full size they simply divide into two or more cells which
grow, and finally attain maturity when the process is repeated.
The other example is that known as the strawberry “runner,” this, as we
know, is only an elongated stem bearing at the end a bunch of leaves,
and from the base of the leaves a few roots, the whole being a new
plant which may be removed from the parent and grown in some other
place.
These, then, are examples of vegetative reproduction, and my readers
can discover for themselves many other instances in the garden.
The plan of propagation by “cuttings” is simply the gardener’s
practical application of vegetative reproduction.
The second mode of increase is by special reproductive cells, which are
set free by the parent plants and become new individuals. The second
mode is common to all plant-life, and in it two distinct processes can
be observed. We often see on a decayed pear or apple a patch of brown
mould (mucor). If we examine it with a lens we see a little forest of
tiny erect stalks, and upon the apex of each is a round ball containing
reproductive cells, each of these, which are called spores (the
spore-case being called the sporangium), contains protoplasm, which is
endowed with the power of giving rise to a new individual mould.
This process is typical of what is common to ferns, and many other
cryptogamic plants, and is called _asexual reproduction_.
The second form is that in which two such spore-like organs as we have
noticed in the mould, fuse together and form a spore capable of giving
rise to a new plant.
This is known as _sexual reproduction_, and is dependent upon the fact
that the protoplasm of either of the two organs is incapable of giving
rise to a new individual plant, and that they must come in contact and
fuse organically before a new plant can be formed. This process of
fusion I have in an earlier chapter described as fertilisation. The
pollen grain, the fertilising agent, is one of the reproductive cells,
and the other, the ovule, is the cell that has to be fertilised. After
this there is the subsequent development of the ovule into the seed,
and in this seed we may recognise a plant in embryo endowed with powers
not possessed by its parent, that enables it to resist extremes of heat
and cold which would result in many cases in death to the parent plant.
By way of experiment some seeds have been subjected to 40 degrees of
cold, and yet have not lost their germinating power, whilst, on the
other hand, it is known that seeds of some plants growing in sandy
deserts lie baking in the sun for many months in a temperature of over
70 degrees, and yet begin to grow as soon as moisture reaches them.[26]
[26] From “Nat. Hist. of Plants,” p. 554: “It has been proved
experimentally that seeds which have been deprived by calcium chloride
of as much water as possible are not killed even at the boiling point
of water.” Careful experiment has shown that there are three stages of
activity in the life and work of a plant—(1) A _minimum or zero_, at
which the processes are just possible; (2) a _medium stage_ or _optimum
point_ where the activity is the greatest; and (3) a _maximum stage of
heat_ where _growth is arrested_. So that we learn that plant-life can
suffer from too high a temperature as well as that which is too low.
Things to be observed or collected:—Experiments to be made in order to
show diffusion, transpiration, and respiration, collection of oxygen
from water bouquet. Carbon-dioxide from germinating beans. Observe—
Blue mould on fruit.
Strawberry runner.
Rooted cuttings.
Stamens and pistil of any flowering plant.
CHAPTER XIII
_INSECTIVOROUS PLANTS_
“Beyond, the moorland has its wealth
Of pink and purple, blue and gold;
Heather and gorse, whose breath gives health,
And ling, a hive of bees that hold:—
And when there’s moisture in the brake,
The clammy sundew’s glistening glands
’Mid carmine foliage boldly make
Slaves of invading insect bands.”
CHAPTER XIII
INSECTIVOROUS PLANTS
The statement in our previous chapter that the leaf has no power to
absorb nitrogen, has to be received with a certain exceptions. These
exceptions are discovered in a large group of plants, having little
or no botanical relationship, and widely separated as regards their
geographical distribution and habit of growth. The term insectivorous
(insect-eating) has been applied to these by eminent botanists who have
studied their habits and mode of growth. We may, as a preliminary to
our study, summarise the main features of these interesting plants,
because I wish my readers to see in them an extension and elaboration
of the various processes we have tried to investigate in plant-life,
and not a mere description of a few vegetable wonders. Rather would I
point out that in studying these deviations from the ordinary type, as
elsewhere, the young botanist should try to arrive at some explanation
of these peculiarities, bearing always in mind that every part of the
plant is created for some special purpose. This train of thought, if
brought to bear upon our botanical study will prevent our regarding the
contrivances of these insectivorous plants as mere freaks of nature,
which appears to me to be a low and unworthy view to take of such
delicate and wonderful structures.
Occasionally, it is true, we meet with monstrosities, in the formation
of which we fail to see any hidden purpose; but even here by careful
observation we shall probably be able to perceive that it is the result
of some injury or the accompaniment of disease from which plant-life is
no more free than animal-life is.
Let us now trace the features that are common to the plants which form
the subject of this chapter.
Perhaps their most interesting function is that of catching and
retaining insects. This is accomplished in various ways, by viscid
fluids which imprison small flies, as in the leaves of the sundew and
other plants; by movements in the leaves, as in the Venus fly-trap; by
a combination of both, as in the butterwort; or by special pitfalls
and traps, as in the pitcher plants, sarracenias, bladderwort, and
cephalotus. Having caught their prey, these plants dissolve it by
means of an acid secretion; the dissolved animal-life is then absorbed
and appropriated for the purposes of vegetable growth. Not all these
processes are carried on by insect-eating plants. In some, for example,
the secretion of dissolving acid is not very apparent, in others the
absorbing glands are not fully developed; but, briefly, the above
features are those possessed by this singular class of plants, and
there is every reason to believe that powers of this kind are more
widely spread than is usually supposed.
We will now notice a few types in detail.
The sundew (_Drosera rotundifolia_) is the pretty and poetic name of a
plant which may often be found on boggy moors. It is barely an inch in
height, a mere rosette of leaves shaped like a battledore, radiating
from a very short root stock, and bearing, in early summer, a central
flower-stalk from four to six inches high, furnished with a few tiny
white flowers. The whole plant lies close to the ground, and is often
embedded in bogmoss, and, were it not for the bright colour of the
leaves[27] and their sparkling dewy effect, it would be a difficult
plant to find. With the naked eye we can see that the leaves are
covered with hairs, and a lens will show still more plainly that these
hairs have each a club-like end bearing a gummy fluid, in appearance
not unlike glycerine. These globules of fluid sparkle in the sun; hence
the name of sundew and the botanical name of _drosera_, from the Greek
“_aroseros_,” or dewy.
[27] On sunny heaths they are often of a rich crimson tint.
[Illustration: SUNDEW.]
Leaves with glandular hairs are not rare amongst our wild plants, and
if this was the only character that the sundew possessed it would not
be specially noticeable. It is, however, the unusual structure and
behaviour of these hairs that claims our notice. The term tentacle is a
not inappropriate one to apply to these “hairs.” A leaf of sundew, with
all its tentacles standing out at different angles from the surface
of the leaf, and each point armed with a drop of viscid fluid, is an
effective arrangement for catching insects. The bright glistening
drops are a fatal attraction to flies, gnats, and other small insects.
When they alight upon the points of the tentacles they soon find that
they are held prisoners. In their efforts to get free they entangle
themselves more and more on the slimy points of the treacherous hairs.
If we watch the tentacles after a fly has been caught, it will soon
be seen that the hairs are bending over and closely pressing down the
wretched captive. This folding over occupies four or five hours from
the time the capture is made. The glands also begin to give out an
increased amount of gummy secretion, and this flow kills the insect
by stopping up its breathing pores, so that literally it dies of
suffocation. The fluid not only increases in quantity, but becomes
acid, and its effect is to dissolve the insect and render it soluble;
the dissolved parts are then absorbed by the glands and digested. This
interesting process can be watched quite easily by carefully taking up
a few plants of sundew with some of the bog-soil and moss in which they
were growing and placing them in a glass dish, where they will continue
for months in perfect health if kept very wet and covered with a bell
glass.
I once lighted on some magnificent sundew growing on boggy land near
Woolmer Forest. Whilst taking up some roots of it I was persistently
attacked by a stinging fly, and, my hands being occupied, I could
not well defend myself. Happily the sundew acted a friendly part! I
was carrying a tuft of it in my hand when, looking down, I saw my
tormenting fly was securely caught upon its leaves. Somehow one always
feels compassion for the unfortunate, and I confess I tried to rescue
the captive, but the creature’s wings and legs were already so glued
together by the viscid dew that it was impossible to release it, and I
realised more than ever how effective the sundew is as a fly-trap.
In transplanting specimens of drosera great care should be taken that
the leaves are untouched, else, being sticky, they will cling together
and lose their delicate beauty. Every few days the plants may be fed,
and happily they are quite willing to accept very minute pieces of raw
beef, so that flies need not be sacrificed in the cause of science. The
little “beafeater” must not be fed a second time until the hairs have
uncurled and the leaf has fully expanded, showing that the last meal
has been digested. I have kept a large pan of sundew in great beauty
for about four months in summer, and when the glass was taken off and
bright sunshine lit up the jewelled leaves the effect was lovely, and a
magnifying glass showed the structure of the leaves and the prismatic
colouring of the dew-tipped hairs.
[Illustration: VENUS FLY-TRAP.]
The Venus fly-trap is an exotic member of the insectivorous family. Its
leaves are remarkably like an ordinary spring rat-trap. A glance at the
drawing will show its formation. On the two lobes of the leaf are a
row of stiff bristles occupying the precise position of the teeth of a
rat-trap. The inner surface of the leaves is of a reddish colour, due
to its being thickly covered with minute red glands; on each lobe there
are three stiff hairs. If a fly alighted on the leaf and walked across
its surface, it would touch one of these hairs, and no matter how light
the touch might be, the hairs are so sensitive they would convey the
signal to the hinge of the lobes, and they would instantly rise up and
clasp the fly, eventually crushing it to death. Then would follow, as
in the case of the sundew, the emission of acrid secretion and the
absorption and digestion of the insect.
Insect-destroying plants are numerous in the vegetable world. They may
be roughly divided into three groups, although there is no strict line
of demarcation between them. First, those like the red lychnis and
others, which, by means of sticky hairs, catch and kill small insects,
an operation that, so far as we know, results in no special good to
the plant. Then there are those, like the sundew, which catch, kill,
and digest the insect for food; whilst the third group consists of
plants which catch and kill insects, but have no digestive process.
Decomposition of the captured insects takes place, but the absorption
which goes on is simply that of the liquid products of decomposition,
the latter process resulting from the insects being immersed in
fluid. To this latter group belong the pitcher plants (_Nepenthes_)
and sarracenias. These last are North American plants of peculiar
structure and appearance. The leaf is folded and modified into a
tunnel-shaped tube differing in form in the various species. In all
there is a kind of cap or lid to the tube, so that rain is kept out. In
one or two species the lid is so arranged that the mouth is exposed.
In the bottom of these tubes there is usually a quantity of somewhat
slimy fluid. The inner face of the lid and surface just inside the rim
of the tube is smooth, usually of a bright shining colour and covered
with minute honey-secreting glands, a most attractive lure for insects.
Below this honeyed surface the character of the sides of the tube
changes completely; for, down to the fluid, it is covered with stiff
hairs all pointing downwards. Now we see how the trap is set. The honey
just inside the tube is attractive, and the insect feeding finds it
very easy to descend the tube; the smooth surface offers no foothold,
and the downward pointed hairs prevent it from returning, until at last
the insect becomes engulfed in the pool of water at the bottom of the
tube. In this fluid insects generally accumulate, decompose, and become
liquid manure.
[Illustration: SARRACENIA FLAVA.]
In Georgia and North Florida these sarracenias are found in the swamps
in large quantities attaining one to two feet in height, their great
tubes half-filled with insects showing their value in tending to
reduce the swarms of flies which abound in such localities. We can
see from these characteristics of the sarracenia a link between the
insect-eating plants which have a true digestive process and ordinary
plants that obtain their food in part direct from the soil. The
sarracenia is simply making an attempt to collect nitrogenous food
by the aid of its form and sweet secretions; thus it lures on flies
and other insects to their doom, which to the plant means an increased
supply of liquid manure for its nourishment.
[Illustration: BLADDERWORT.]
Between the two types of insectivorous plants and ordinary plants there
are endless varieties. The largest known species of “fly-catcher” is
the _Roridula dentata_ of South Africa, which attains a height of six
feet, with leaves similar to the sundew in character. So efficient are
these leaves in catching flies that the Boers hang up branches in their
rooms as fly-traps.
The smallest insect-eating plant is probably the bladderwort
(_Utricularia vulgaris_), a rootless water plant with minute bladders
on small thread-like leaves. The bladders only open inwards, so that
when an insect pushes against the opening or valve it easily enters,
and cannot get out again. The bladder contains water, but the insect
quickly consumes the oxygen in it, and consequently dies, and when
decayed its substance is absorbed by glands on the inner surface of the
bladder.
[Illustration:
PITCHER OF NEPENTHES RAFFLESIANA.
]
Perhaps the most attractive of the group of plants we are considering
is the pitcher plant or Nepenthes. It grows commonly in Borneo and
Ceylon. The pitcher is a direct development of the midrib of the
leaf. It varies in size from the little thimble-like pitcher of
_Nepenthes gracilis_ to the large jug-like receptacles of _Nepenthes
Rafflesiana_[28] and others, each capable of holding nearly a pint of
fluid. The pitchers are furnished with a lid overhanging the mouth of
the receptacle, this is kept open by a thick rim. This rim and the
under-surface of the lid both secrete a sweet fluid which is attractive
to insects, and from the rim and opening of the mouth a smooth surface
directs the ill-fated flies to the sweet sticky fluid always found at
the bottom of the pitcher, out of which they rarely come alive.
[28] See Frontispiece.
Another of our native plants exhibiting these insectivorous habits is
the butterwort (_Pinguicula_). Like the sundew it is a mere rosette of
radical leaves, having upturned margins and a very succulent pellucid
appearance. These leaves are covered with glands which exude a viscid
kind of fluid like that on the tentacles of the sundew. This natural
birdlime catches and holds small flies, midges, and other tiny flying
creatures, as well as crawling insects. The presence of these insects
on the leaf appears to stimulate it to further secretion which must,
of course, lessen the chances of the insect’s escape, and as a further
barrier to prevent its creeping away, the edges of the leaf begin
slowly to curve inwards, so that the caught insect is imprisoned in the
folds of the leaf. The acid secretion which now exudes from the glands
soon dissolves all the nitrogenous and soft parts of the insect, which
are taken up by the absorptive glands of the leaf. There are many other
plants, of which I have not space to make mention, although they are
full of interest, as owing to their curious structure, it is probable
that insectivorous habits might also be ascribed to them. The field
of study is a wide one, and throws much light upon the physiology of
plants as well as the relationship between the plant and animal world.
I would suggest to my young readers, as a practical means of knowing
more of this subject, to try and grow for themselves the sundew,
pinguicula, and sarracenia.
[Illustration: BUTTERWORT.]
The two first can be found, as I have already said, on boggy moors in
England, and the latter plant can be obtained from any florist. All can
be successfully grown in a greenhouse or garden frame, and studying
their growth and habits in this way will teach the young botanist far
more agreeably than learning only from books.
At Kew there is always a fine collection of these insectivorous plants
to be seen in vigorous growth, whilst at the South Kensington Natural
History Museum (Botanical Department) there are some highly interesting
cases illustrating the life history of these remarkable plants.
CHAPTER XIV
_HABIT OF GROWTH IN PLANTS_
“Some clothe the soil that feeds them, far diffused
And lowly creeping, modest and yet fair,
Like virtue, thriving most where little seen;
Some, more aspiring, catch the neighbour shrub
With clasping tendrils, and invest his branch,
Else unadorn’d, with many a gay festoon
And fragrant chaplet, recompensing well
The strength they borrow with the grace they lend.”
+Cowper.+
CHAPTER XIV
HABIT OF GROWTH IN PLANTS
My readers have possibly noticed that in the previous chapters my aim
has been to describe the various organs of a plant, and that I have
tried to show not merely the botanical meaning of the many differences
in the organs of allied species, but to point out also how these
structures are adapted to help the plant to multiply itself. The object
of this final chapter is to take a more general view of plant-life,
and to give some idea of the different habits of plants; how in their
struggle to grow and reproduce themselves they form such habits as tend
to assist them in this effort, and also how entirely, in some cases,
they differ from our ordinary conception of plant-growth.
We have already seen how beautifully plants are adapted to the life
they have to lead, how they are specially fitted to grow in some
particular place and climate, and now I will ask my readers to study
with me certain of the varying habits of plant-life. A typical plant of
an ordinary kind grows, of course, in the earth, produces root, stem,
and leaves, and finally flowers, which are the origin of fruits and
seed; by the latter the plant is again produced, and by this circular
action the continuity of that particular plant is maintained.
Let us now, in imagination, peep into a tropical forest. On its
outskirts we shall see the prototypes of our typical plant; but inside
there are also others of quite a different aspect, and the first to
attract our attention would probably be the curious orchids perched
upon the tree-branches. Their mode of growth differs greatly from that
of a normal plant, for they are merely attached to the branches by
means of clasping rootlets, which do not in any way extract sap from
the tree to which they are clinging.
The moisture they need is collected by the leaves and hanging rootlets
from the humid atmosphere of the forest. These plants that have
acquired a perching habit sometimes grow to an immense size, and where
they do so vegetable _débris_ accumulates about their lower leaves and
roots to such an extent that it serves to supply them with needful food.
[Illustration: PERCHING ORCHID.]
This habit of growth is not confined to the lovely orchids; mosses,
lichens, ferns, and many other plants have acquired a similar mode of
growth, and the various ways by which they attach themselves to the
bearer plants would form an interesting subject of investigation. It
is a not uncommon error to regard these perching plants as parasites,
but this term is properly used for plants which actually feed upon the
branches of the trees where they grow, and of course seriously injure
the trees by so doing. The orchids, on the other hand, do not in any
way injure the branch upon which they rest. Robert Louis Stevenson in
one of his later poems has, with a poet’s license, which in this case
is contrary to fact, described the perching orchid thus—
“For in the groins of branches, lo!
The cancers of the orchid grow.”
This inaccurate observation is, however, more than atoned for by
the wonderful impression Stevenson has given us of the character of
woodland strife, the ceaseless struggle for light and air which goes on
in tropical forests.
In studying the parasites as a group of plants associated by the
same habit of growth, we are led to the conclusion that there is some
difference after all in the morality of plants! Here, for example, we
are confronted with a group of plants that differ entirely from those
we have hitherto examined. The mistletoe, which is the commonest type,
is certainly lower in the social plant-scale than the perching orchid,
the latter with its leaves and rootlets being enabled to earn its own
living, while the mistletoe sends its roots down into the soft sap of
the branch upon which it is growing and—there is no other name for
it—steals its means of living and growing from the substance of the
poor tree upon which it preys. It is true it does, in a half-hearted
kind of way, assimilate a little gaseous food for itself, but the
sickly metallic hue of its leaves is evidence that even in this respect
it is shirking its proper duties of nutrition.
[Illustration: RAFFLESIA ARNOLDII.]
If we desire to study the curious habits of parasitic plants, the two
examples referred to in a previous chapter, the clover-dodder and
the yellow rattle, will afford good examples, the latter plant being
easily obtainable in fields where the pasture is poor and scanty. Very
curious are the modifications and contrivances developed by plants
which have acquired this habit of parasitism, especially amongst such
weird tropical species as _Rafflesia_, a huge parasite growing on the
_Cissus_ in Sumatra. When the leaves and flowers of the cissus have
withered, then here and there a huge knob protrudes from the stem or
root, and this grows in time to an immense stemless flower, measuring
more than three feet across, its cup frequently containing as much as
twelve pints of liquid, and the weight of the whole flower being said
to be about fifteen pounds.
Differing a little in habit from the parasites are the _saprophyte_
plants, which live on decaying vegetation. The little brown leafless
orchid called the bird’s-nest orchis is of this character, as well
as the equally curious coral-root orchis. These plants, as well as
many other parasites, are destitute of chlorophyll, and are therefore
dependent on organic material for food; this they obtain either as we
have seen from living plants or from decaying organic matter. In their
efforts to obtain a needful supply of light and air, some plants assume
climbing habits, using as supports other trees and plants, to the very
obvious disadvantage of the latter. We can well understand how, in a
tropical forest, the weak-climbing plants strive to pass out of the
shaded recesses and force their way to the tops of the slower growing
trees, in order to obtain the share of light, moisture, and air which
are essential to their existence. Very vividly has the late Mr. Louis
Stevenson described such a scene in a tropical forest—
“The hooked liana in his gin
Noosed his reluctant neighbours in;
There the green murderer throve and spread,
Upon his smothering victims fed,
And wantoned on his climbing coil.
Contending roots fought for the soil
Like frighted demons; with despair
Competing branches pushed for air.”
* * * * *
“So hushed the woodland warfare goes
Unceasing; and the silent foes
Grapple and smother, strain and clasp
Without a cry, without a gasp.”
I may explain that the “murderer” alluded to is a species of fig-tree
which, in its early youth climbs up the trunks of other trees, and
by means of its clasping roots so constricts their stems that they
ultimately perish.
In pleasing contrast to this phase of vegetable growth is the habit
which indicates to us something of mutual help and co-operation. In
the _Compositæ_ we find many instances of a habit of growth that bears
distinctly upon this “help-one-another” mode of life. A common daisy
will serve as a type-flower of this kind. The little head is a colony
of flowers, but so close is the association of its individual florets
that it is usual to regard it as one flower rather than a distinct
inflorescence composed of numerous separate and distinct flowers.
In order to understand the mutualism displayed by this little flower,
we must remember that it is an insect-fertilised blossom, and,
therefore, insects must be attracted to it. If we carefully dissect a
flower-head we shall find first a ring of strap-shaped flowers on the
outside, constituting the ray florets—these are imperfect;[29] but
placed side by side on the outer edge they become conspicuous; then we
find in the centre of the flower-head a number of tiny yellow flowers,
each one containing stamens and pistils. What wee things they are, and
if they were developed singly how inconspicuous they would be! When,
however, they are grouped side by side in the centre, and further, when
the outer florets are of a different colour and shape, what a beautiful
and symmetrical whole they make! Truly this is another rendering of
the maxim, Union is strength. From a different point of view the
arrangement is equally interesting. The white and pink tipped florets
of the ray are not capable of bearing seed, and yet we see how they
help those florets that are perfect by their attractive appearance;
then at night or on a cold rainy day these same ray florets bend over
and completely cover up the florets in the centre which are busy
producing seed. My readers will find a rich field of investigation open
before them in studying the flowers of the daisy family, and finding
out for themselves how the florets are grouped together, and to what
extent this principle of co-operation can be traced.[30]
[29] Barren.
[30] A single flower of the Heracleum giganteum would not be specially
noticeable, but when hundreds of them are grouped together in a huge
umbelliferous head they form a most striking object, as may be seen in
the plate. I have often watched the swarms of flies, beetles, and bees
visiting these attractive blossoms on sunny days, and the great umbels
of seed in autumn showed how effectually the insects had carried out
their work of fertilisation.
[Illustration: +GIANT COW-PARSNIP+ (_Heracleum Giganteum_).]
Students will find the corn blue-bottle especially interesting; the
large outer florets contain no organs of reproduction, but still they
are brightly coloured and highly attractive to bees; the inner florets
with their protruding stigmas and anthers, are much smaller; they are
the seed-bearers, and cannot fail to receive pollination when the
bee alights on the flower-head, allured by the showy outer florets,
which apparently exist solely that they may draw insects to visit the
unattractive flowers of the disc.
[Illustration: CORN BLUE-BOTTLE.]
The direct influence of the separate parts of a plant upon one
another, and the very distinct habit of associating together that
they may attain some end such as the visits of insects, leads us to
consider two other aspects of plant-life, both of which are so full
of interest that no botanical work can now be considered complete
without some reference to the matter. If we carefully dig up a clover
plant or a broad bean and examine the little rootlets we shall observe
some small knobs or swellings upon them. These swellings are only
found here and there on some of the roots, so that their presence is
not a normal condition. Placing one of these knobs under a powerful
microscope, we shall find it to be not ordinary root tissue but a
substance teeming with countless numbers of rod-like or rounded atoms
which botanists who have investigated the subject tell us are bacteria,
_i.e._, inconceivably small one-celled plants which are often the
cause of terrible diseases. But some of these mysterious organisms,
on the other hand, are capable of beneficial results. It has of late
been clearly proved that leguminous plants having these colonies of
bacteria on their roots possess the power of assimilating the free
nitrogen that forms such a large proportion of atmospheric air. When
therefore a farmer sows his wheat in a field previously occupied by
clover he finds the clover roots left in the soil contribute the best
possible supply of nitrogen to the wheat crop. This seems a remarkable
fact, since vegetable physiologists have hitherto insisted upon the
fact that plant-life is unable to make use of the free nitrogen of the
air. The other instance of strange habit is that of a symbiosis,[31]
which exists between certain trees on the one hand and the threads of
spawn of some fungi on the other. If the roots of the white poplar are
examined minutely, quite a mantle of whitish threads will be found
covering the growing point. It is said by that eminent botanist,
Professor Kerner, and by others that, as the roots are developed from
the young seedling-tree, they are enclosed in the meshes of the fungus,
and that this particular fungus is always a close associate of the
roots as they grow in all directions. This fact we can see when we
dig up the roots, but the most striking part of the story is this,
that between this fungus root and the roots of the tree there is an
organic connection, a division of labour which results in the tree
receiving from the thread-like filaments of the fungus (_hyphæ_) both
moisture and certain food stuffs from the ground, whilst the fungus
gets in return such organic food as the tree has produced by means of
its green leaves. Such cases as these present to us a manner of growth
that is akin to social habit, and, strange as the union may appear, the
circumstance is by no means uncommon in the vegetable kingdom. Stranger
still perhaps is the union that is sometimes to be found between plants
and some member of the animal world, of which union I shall give an
example. On one of the larger species of sea-anemones (_Anthea cereus_)
are small yellowish spots, which at one time were supposed to form
part of the animal itself. But now the spots turn out to be vegetable
cells, which can be isolated and induced to continue growing after
the death of the anemone. The yellow spots are small algæ, and are
furnished with chlorophyll. We must not regard the algæ as parasites
on the sea-anemone, because they split up the carbon-dioxide under the
influence of sunlight, and by so doing supply the anemone with oxygen
for respiration, whilst the starch formed in the protoplasm of the algæ
passes by diffusion into the anatomy of the animal. The transaction
does not end here; the algæ in all probability receives nitrogenous
substances in return, so that there is a mutual interchange.
[31] A word meaning two plants living together and deriving mutual
benefit.
These are but one or two of the many wonderful phases of vegetable
life, and I hope by thus briefly sketching a few of them my readers
will be stimulated into a greater desire to explore God’s marvellous
works in nature. There is an endless succession of such wonders to be
investigated, but in order to find them we need a careful spirit of
observation, passing nothing by without trying to learn something of
its life history. Every hedgerow is full of delightful problems which
will reward the interested student. A single field has been found to
contain as many as fifty different species of plants, and every month
of the year will present a new aspect of life. In the early spring we
have the germinating seed and the tiny growing moss. A little later the
opening buds with their wealth of interesting points to study, then the
unfolding of the leaves and the gradual development of the flower.
Here and there a climbing plant will engage our attention, its mode of
climbing, its modification of part or parts to enable it successfully
to overcome difficulties, its acceptance of help by the way—as in the
case of a bryony tendril I once came across which cleverly attached
itself to a minute hole in a laurel leaf—these and many other items
will interest us in our walks if we keep our eyes open.
[Illustration: BRYONY TENDRIL.]
Then, as summer slowly passes away and autumn approaches, the fruits
will engage our attention; their forms and shapes and modes of
dispersion will afford ample subjects for study.
[Illustration: TRICHIA THROWING OUT SPORES.]
Winter, too, still brings its store of pleasure for the young botanist.
Nature is not dead—she only sleeps. Nay, unless there is hard frost and
deep snow the field for observation is just as wide and the harvest
as plentiful as at any other season. Look on the old apple-trees and
see what a host of tiny plantlets there is there to glean. Here are
pale-green bearded moss and lichens, there a branch, perhaps, lies
on the ground dead and decaying, under whose mouldering bark, if we
have keen eyes, we may discover tiny tufts of the _Mycetozoa_, whose
capsules, under the microscope (and in some cases even with the naked
eye) are seen to give off clouds of spores, actually thrown out by the
active movements of fine waving threads, a sight never to be forgotten
when it has been watched under favourable circumstances. Winter is
also rich in its harvest of mushroom-like fungi; these will well repay
a little study. We shall be led to note their form, colour, mode, and
habit of growth, how they affect certain trees and soils, and the
important difference of some kinds being eatable and others virulently
poisonous; the mere book student can know very little of the keen
pleasure enjoyed by those who thus think about what they see, and are
ever adding to their stock of knowledge by personal observation. I may
close with some true and beautiful thoughts by one[32] who is herself a
reverent student of the book of nature.
[32] Miss Blanche Atkinson, member of the Barmouth Branch of the
Selborne Society.
“No pleasure is more sure and none less costly than that of watching
day by day the signs of the coming spring; than the delight of seeing
unexpectedly the first primrose, and of finding that the anemones
and hyacinths are pushing their way to the sunshine. Year by year the
miracle of springtime, when the green leaves are shaken forth from the
hard bud is more miraculous. Summer after summer the lilies are fairer,
the wild roses more exquisite, and on through the seasons the varying
pleasures succeed one another. These things never pall; and if the time
should come when we can no longer go out to the hills and woods to
welcome the spring and revel in the bounty of summer we know that the
past is not lost. The fair remembrance of the flowers of the field is
safe in our hearts, and will ‘flash upon that inward eye which is the
bliss of solitude.’”
_GLOSSARY OF SCIENTIFIC WORDS USED IN THIS VOLUME_
GLOSSARY.
A clear definition of scientific terms involves an exact knowledge
of several languages, and when translated into technical phraseology
these definitions often appear to me to be as difficult to a simple
comprehension as the original words they purport to explain.
I have endeavoured therefore, in this glossary, to put scientific terms
into plain words as clearly as was consistent with the facts, and not
by any means to attempt a really exhaustive scientific definition.
A
_Absciss_—A term applied to a layer of separating cells.
_Absorption_—Taking in food by diffusion.
_Accessory_—Anything additional.
_Acetic_—Applied to an acid, sour.
_Achene_—A small dry indehiscent fruit with a leathery coat.
_Adaptation_—As applied to plant-life meaning the structure of the
plant becoming most fitted to its environment.
_Adventitious_—Not developed in regular order.
_Aerial_—Inhabiting or existing in the air.
_Æstivation_—The arrangement of the parts of the flower in the bud.
_Albumen_—Reserve material contained in the seed, analogous to the
white of an egg.
_Alchemilla_—A genus of rosaceous plants with small green flowers.
_Allium_—The onion genus.
_Altitude_—Height.
_Ampelopsis_—A genus of climbing plants allied to the vine whose leaves
are brilliantly coloured in autumn.
_Anemophilous_—Pollinated by the wind.
_Animalcule_—Microscopic insect life.
_Annual_—A plant whose duration of life is one season: _Ex._ mignonette.
_Anthea_—A genus of sea-anemones.
_Anther_—The dilated end of the stamen in which the pollen grains are
developed.
_Antheridium_—The case containing the antherozoids in cryptogamic
plants.
_Antherozoides_—The male cell, or active member in fertilisation of
cryptogams.
_Antirrhinum_—The snap-dragon genus.
_Antiseptic_—Counteracting decay or putrefaction.
_Apocarpous_—Applied to the pistil when the carpels are distinct or
when the pistil consists of one carpel.
_Appendages_—Something hanging or appended, extra.
_Aquatic_—Relating to water.
_Araucaria_—The generic name of the monkey-puzzle tree.
_Archegonium_—The flask-shaped organ containing the female cell in the
cryptogams.
_Arid_—Dry and waterless.
_Arillus_—An out-growth from the funicle (or seed-coat).
_Aristolochia_—A genus of climbing plants with curious “prison” flowers
which attract and retain insects.
_Arum_—A genus of poisonous plants with an inflorescence consisting of
spadix and spathe.
_Asexual_—Not sexual.
_Asparagus_—A genus of edible vegetables and climbing plants.
_Assimilation_—The conversion of crude food into protoplasm.
_Aster_—The generic name of the Michaelmas daisies.
_Avena_—The generic name of the oat.
_Awn_—The beard of barley and other corn.
_Axillary_—Growing in the axil of the leaf.
B
_Bacteria_—Minute one-celled living atoms, the cause of most contagious
diseases.
_Bamboo_—A giant grass.
_Banana_—The fruit of the genus Musa.
_Bark_—The rough external part of a stem.
_Barm_—Same as yeast.
_Bast_—The fibrous tissue between the bark and the wood of a
dicotyledonous stem.
_Begonia_—A genus of plants with bright flowers and oblique or
one-sided leaves.
_Betula_—Generic name of the birch-tree.
_Biennial_—A plant whose duration of life is two seasons: _Ex._
Beetroot.
_Bifacial_—With upper and lower sides structurally different: _Ex._
laurel leaf.
_Bignonia_—A genus of flowering climbing plants.
_Blade_—The broad part of the leaf.
_Bougainvillia_—A genus of climbing tropical plants with bright pink
bracts and small yellowish flowers.
_Bulb_—A dormant bud surrounded with fleshy scales.
_Bulbils_—Small bulbs.
_Bunium_—A genus of tuberous Umbelliferæ, earthnut.
_Buoyant_—Light, able to float in air or water.
_Button-wood_—A term applied in America to the plane tree.
C
_Cacti_—A family of succulent plants usually devoid of leaves.
_Caducous_—Quickly dropping off.
_Calceolaria_—A genus of herbaceous garden plants with pouched flowers.
_Calcium_—An element present in all calcareous rocks.
_Calyptra_—The hood of a moss-fruit.
_Calyx_—The outer whorl of the flower or floral envelope, cup-shaped.
_Cambium-layer_—A layer of active growing tissue.
_Campanula_—A genus of Alpine and herbaceous plants with bell-shaped
flowers.
_Camphor_—A drug obtained by dry distillation of the leaves and stems
of Camphora officinarum.
_Capillary_—Fine and minute, hair-like.
_Carbon-dioxide_—Symbol CO₂. A gas existing in small quantities in
the air, otherwise called carbonic-acid gas.
_Carbon-monoxide_—A poisonous gas whose molecule is composed of one
atom of carbon and one atom of oxygen.
_Carex_—A genus of sedge-like plants.
_Carpel_—A pistillate leaf, one of the component parts of the pistil.
_Caterpillar_—The form of an insect after it is hatched, first stage.
_Catkin_—A spike of staminate or pistillate flowers usually pendulous.
_Checkered_—Outlined into a square-like pattern.
_Chevaux de frise_—An obstacle consisting of iron spikes set in a
framework of iron.
_Chlorophyll_—The green colouring matter of leaves and stems.
_Cholera_—A contagious disease.
_Chrysalis_—_pl._ Chrysalides. The form assumed by some insects before
they reach the winged state.
_Chrysanthemum_—A genus of showy flowering plants belonging to the
Compositæ.
_Cinchona_—A genus of trees yielding quinine.
_Circumnutation_—The rotating motion made by the growing point of the
stem and leaf.
_Cissus_—A genus of vine-like plants often with brilliant coloured
leaves.
_Climatic_—Influenced by a climate.
_Coalesce_—To fuse, cohering of parts not usually joined.
_Cocos-de-mer_—The large double cocoa-nut tree of the Seychelles Isles.
_Collomia_—A genus of plants whose seeds are remarkable for the spiral
fibres which expand elastically when wetted.
_Compositæ_—A group of plants having an inflorescence of florets
arranged upon a common receptacle or head.
_Concentric_—A number of rings having a common centre.
_Cone_—The hard woody fruits of the fir-tree.
_Coniferous_—Fir-like, or cone-like; belonging to the cone-bearing
family.
_Continuity_—Unbroken succession.
_Corolla_—The second whorl of the floral envelope usually brightly
coloured.
_Corpuscles_—Grains or granular.
_Correlation_—_i.e._, connection, interdependence.
_Cortex_—The bark or outer covering of stems.
_Cotyledon_—A seed leaf.
_Cruciferæ_—A group of plants having their petals arranged crosswise,
with six stamens two of which are longer than the others.
_Cryptogamic_—Relating to flowerless plants.
_Culm_—The straw-like stems of the grasses.
_Cuscuta_—The dodder genus, parasitic upon flax and clovers, &c.
_Cuticle_—The exterior and thickened part of the epidermis.
_Cyclamen_—Dwarf primulaceous plants with shortened stems (corms).
D
_Dahlia_—A genus of tuberous-rooted plants.
_Darlingtonia_—A genus of Californian plants related to the side-saddle
plants.
_Datura_—The generic name of the thorn-apple.
_Débris_—Remains, rubbish.
_Deciduous_—Applied to plants, the leaves of which fall off in autumn.
_Dehiscent_—Splitting open when ripe.
_Deodar_—A tree allied to the cedar of Lebanon.
_Dentaria_—A cruciferous plant bearing bulbils in the axils of the
leaves.
_Diagrammatic_—Drawn to illustrate a statement.
_Dicotyledon_—A plant whose embryo has two primary seed-leaves.
_Diffusion_—The intermingling of fluids (gases or liquids).
_Diœcious_—When the pistillate flowers and staminate flowers are borne
upon separate plants of the same species.
_Dispersion_—Scattering.
_Drosera_—The generic name of the sundews.
E
_Elastic_—Springy.
_Embryo_—The future plant contained in the substance of the seed.
_Embryo-sac_—The cavity in the substance of the nucellus, containing
the egg-cell, which after fertilisation becomes the embryo.
_Endocarp_—The inside layer of the pericarp.
_Entomophilous_—Pollinated by insects.
_Epicarp_—The outside layer of the pericarp.
_Epidermis_—A layer of generally flattened cells forming the skin of
the plant.
_Epigean_—Developed like the cotyledons of mustard, above ground.
_Epipetalous_—Growing upon the petals.
_Erysipelas_—A disease of the blood causing a red eruption.
_Eucalyptus_—The generic name of the Australian blue gum tree.
_Euonomin_—A dry extract made from the root-bark of Euonymus
altro-purpureus, a North American shrub.
_Euonymus_—A genus of shrubs and hedgerow trees.
_Euphorbia_—The spurge genus.
_Exogen_—Growing by addition to outside of wood and inside of bark,
synonymous with dicotyledon.
F
_Fermentation_—Changes that take place in wort when barm or yeast is
added, or when fluids are exposed to the air. _See_ Yeast.
_Fertilised_—Completion of the act of fertilisation, _i.e._, fusion of
the male element contained in the pollen tube with the egg cell of the
ovule.
_Fibrous_—Meaning a structure of fine loose filaments or hairs, _i.e._,
young rootlets.
_Fibro-vascular_—A compound tissue of fibres and vessels.
_Filament_—A thread-like fibre.
_Flaccid_—Want of firmness, soft and lax.
_Fructification_—The fruit system of a plant.
_Fuchsia_—A genus of exotic flowering plants having a petaloid calyx.
_Function_—As applied to plant-life, meaning the use and lifework of
the members of a plant.
_Fungoid_—Growth like a fungus.
G
_Gamopetalous_—Petals united.
_Gamosepalous_—Sepals united.
_Genesis_—Creation, production.
_Germinate_—The change of the seed from the dormant state to the active
growing stage.
_Gloxinia_—A genus of popular hothouse plants with large handsome
flowers.
H
_Habitat_—The natural abode of a plant.
_Herbaceous_—Applied to plants which do not form a hard woody stem.
_Herbarium_—A collection of dried plants.
_Hexagonal_—A six-sided and angled figure.
_Hibernating_—Sleeping, a dormant condition.
_Hilum_—The black scar on a bean seed.
_Hippuris_—A genus of aquatic flowering plants.
_Horizontal_—Parallel to the horizon level.
_Hoya_—A genus of tropical climbing plants.
_Hyacinths_—Bulbous plants.
_Hydrangea_—A genus of flowering shrubs.
_Hygienic_—Relating to the preservation of health.
_Hygrometric_—Moisture and its influence.
_Hygroscopic_—Applied to the film of water surrounding the particles of
the soil.
_Hypericum_—The generic name of the St. John’s wort.
_Hyphæ_—Filaments or threads of the fungus spawn.
_Hypogean_—Development of the cotyledons under ground.
I
_Impatiens_—The generic name of the balsam.
_Impervious_—Not to be penetrated by water.
_Insectivorous_—Catching and killing insects, plants that have this
power and can absorb the decomposed insects.
_Insoluble_—Substances that do not dissolve in water.
_Intercellular_—Spaces between the cells.
_Internode_—The space between two nodes.
_Involucre_—A whorl of bracts.
_Iodine_—A soluble substance extracted from kelp and used as a test for
starch.
L
_Laburnum_—Yellow-flowered trees allied to the Pea family (Leguminosæ).
_Legume_—The dehiscent fruit of the pea family, a pod.
_Leguminosæ_—A family of plants having for their fruit a legume or pod,
_i.e._, Pea, Laburnum.
_Lenticels_—Minute pores in the bark.
_Liane_—A hanging root or stem.
_Liber_—The inner bark, same as phloëm.
_Linnæa_—A genus of dwarf trailing plants.
_Luscious_—Sweet and succulent.
M
_Magnesium_—The metallic base of magnesia.
_Magnolia_—A genus of flowering shrubs and trees.
_Mahonia_—A genus of evergreen shrubs belonging to the barberry family.
_Martynia_—A genus of plants having capsules with long curved hooks.
_Melampyrum_—A genus of dwarf flowering plants partly parasitic.
_Membranous_—Thin and destitute of green colour usually applied to
bracts.
_Mesocarp_—The central layer of the pericarp.
_Mesophyll_—The ground tissue of the leaf.
_Metabolism_—Changes which take place in protoplasm and which it causes
in other substances.
_Microbes_—A term applied to one-celled plant atoms, like bacteria.
_Micropyle_—A small pore in the coats of the ovule through which the
pollen tube passes.
_Modicum_—Moderate sized; a small quantity.
_Monocotyledon_—A plant whose seed is furnished with one seed leaf.
_Monœcious_—Applied to a plant when the stamens and pistil are in
distinct flowers.
_Monstera_—A genus of climbing aroids with edible fruit.
_Mucilaginous_—Sticky, gumlike, secreting mucilage.
_Mucuna_—A genus of Brazilian Leguminosæ, yielding the cowage
(consisting of intensely irritating hairs), of the Materia Medica.
_Mutualism_—Interchange of some advantage, botanically applied to the
union of two dissimilar plants which live in _close_ contact with each
other to their mutual benefit.
_Mycelium_—The root-like colourless filaments of fungi.
_Mycetozoa_—A term applied to the slime-fungi.
N
_Nectary_—A honey secreting gland or spur.
_Nemophila_—A genus of dwarf annual flowering plants.
_Nepenthes_—A genus of plants having as a prolongation of the midrib of
the leaves, ascidia or pitchers.
_Nocturnal_—Happening by night.
_Node_—The exact point on the stem from which the leaf is developed.
_Normal_—Regular, unaffected by any modification.
_Noxious_—Hurtful or poisonous.
_Nucellus_—The internal tissue of the ovule within which the embryo-sac
is embedded.
_Nutrition_—The process and function of taking in food for the purpose
of growth and to replace waste.
O
_Orchis_—A genus of the orchid family growing in the soil.
_Osmosis_—The passage of fluids through a membrane.
_Ovary_—The ovule case, that part of the carpel that bears ovules.
_Ovule_—The structure which after fertilisation forms the seed.
_Ovum_—The egg cell of the ovule.
_Oxalis_—The generic name of the wood sorrel.
_Oxygen_—A gas, one of the constituents of the atmosphere.
P
_Palisade-tissue_—A tissue of oblong cells placed side by side at right
angles to the flat surface of the leaf.
_Papilionaceous_—Butterfly shaped.
_Pappus_—A light hairy development from the calyx of some plants.
_Parasitic_—The habit of growing upon and deriving nourishment from
another plant.
_Pellucid_—Shining and transparent.
_Perennial_—Plants that live for an indefinite period.
_Perianth_—A term used when there is no distinction between calyx and
corolla.
_Pericarp_—The ripened walls of the ovary constituting the structure of
the fruit.
_Persistent_—Applied to the parts of the flower that remain on for some
time.
_Petunia_—A genus of Brazilian Solanaceæ.
_Philodendron_—A genus of aroids usually climbers.
_Phleum_—A grass.
_Phloëm_—The inner bark, containing sieve-tubes.
_Phosphate_—A salt formed by the union of phosphoric acid with some
base.
_Phyllotaxis_—The law of leaf arrangement.
_Physalis_—The generic name of the winter cherry.
_Physiological_—Having reference to the function or life work of the
plant.
_Picea_—A genus of the Conifer family.
_Pinetum_—A garden devoted to the culture of pine-trees.
_Pinguicula_—The generic name of the butterworts.
_Pinus_—A genus of the Conifer family.
_Pistil_—The female part of the flower consisting of ovary, style, and
stigma.
_Pistillate_—Applied to flowers having the pistil only.
_Pith_—The soft tissue in the centre of the stem.
_Plumbago_—The generic name of the leadworts, small flowering plants
and shrubs.
_Plumule_—The first stem shoot of the germinating seed.
_Poa_—A grass.
_Poinsettia_—A genus of Mexican plants having bright scarlet bracts and
small flowers.
_Pollard_—A tree trunk with its branches cut short.
_Pollen_—The fertilising or male part of the flower.
_Pollination_—The act of conveying the pollen from the stamen to the
stigma.
_Polypetalous_—Separate or many petals.
_Polysepalous_—Separate or many sepals.
_Polytrichum_—The generic name of the hair moss.
_Potassium_—The metallic base of potash.
_Proboscis_—The feeling and feeding organ of an insect.
_Prothallus_—The first growth when the spore of a fern germinates.
_Protococcus_—A genus of unicellular plants forming a green stain upon
trees, &c.
_Protonema_—The first growth of the moss-spore.
_Protoplasm_—A highly complex substance forming the essential part of
all living cells, and to which all life growth is due.
_Prototypes_—First forms of plant-life.
_Psamma_—A genus of the grass family.
_Pseudo-bulb_—A swollen stem common in the epiphytic orchids.
_Pteris_—The generic name of the bracken fern.
Q
_Quiescent_—Inactive, dormant.
_Quinine_—An alkaloid extracted from the cinchona trees.
R
_Radicle_—The first formed root when a seed germinates.
_Rafflesia_—A genus of brown leafless parasites.
_Receptacle_—That part of the stalk on which the flower is developed.
_Resin_—A secretion from certain trees which hardens on exposure.
_Respiration_—The process of breathing.
_Rhinanthus_—The generic name of the yellow-rattle (a root parasite).
_Rhododendron_—A genus of popular flowering shrubs and dwarf trees.
_Root-cap_—A loose covering of tissue that protects the extreme point
of the growing root.
_Root-hairs_—The delicate unicellular hairs found on the young root.
S
_Salicine_—A substance obtained from the bark of willows, soluble in
water and alcohol, and crystallising in bright white needles.
_Salvia_—A genus of labiate plants.
_Samara_—Winged fruit.
_Saprophyte_—Plants that live upon decaying organic matter.
_Sarracenia_—The generic name of the North American side-saddle plants.
_Saxifraga_—A genus of dwarf Alpine plants.
_Scales_—Rudimentary leaves.
_Secretion_—Applied to substances like resin and honey, the production
of assimilation and metabolism.
_Sedum_—A genus of succulent Alpine plants.
_Soluble_—Any substance that dissolves in water.
_Spadix_—The inflorescence of the Aroideæ.
_Spathe_—The bract of the Aroideæ.
_Sporangium_—The spore-case of some of the cryptogamia.
_Spurious_—False.
_Stapelia_—A genus of succulent plants, very poisonous and fœtid.
_Starch_—Colourless grains, a product of assimilation in the leaf.
_Stigma_—The receptive part of the pistil.
_Stipa_—A genus of the grass family.
_Stipules_—Small outgrowths at the base of the petiole.
_Stomata_—Minute pores in the epidermis of the leaf or green stem.
_Sulphate_—A salt formed by the combination of sulphuric acid with some
base.
_Sycamore_—The plane tree of Scotland, Acer pseudoplatanus.
_Symbiosis_—Mutualism, a living for one another, interchange of
benefits by united growth.
_Syncarpous_—United carpels.
T
_Tannin_—A substance widely diffused through the leaves and stems of
plants, of an astringent character.
_Tap-root_—A root that forms an unbranched tapering axis: _Ex._, carrot.
_Tendril_—A coiled or hooked filament modified to assist plants to
climb.
_Tentacles_—The glandular and feeler-like hairs of the sundew.
_Terminal_—At the apex or end.
_Testa_—The skin of seed.
_Tigellum_—The first stalk of the seed bearing the cotyledons.
_Tillandsia_—A New World genus of perching or epiphytic plants.
_Tissue_—A group of cells; having a common origin.
_Tormentilla_—A genus of small creeping rosaceous plants.
_Transpiration_—The giving off of water vapour from the surface of
leaves and stems.
_Tricyrtis_—The generic name of the toad-lily.
_Tuber_—A fleshy root or succulent underground stem.
U
_Umbelliferæ_—A group of plants having an umbellate arrangement of the
inflorescence or flower-head.
V
_Vallisneria_—A genus of aquatic flowering plants.
_Valved_—Having valves, _e.g._, anther of the barberry.
_Vapour_—Gas into which most liquids and solids are converted by heat.
_Vasculum_—A little vessel or box for collecting botanical and other
specimens.
_Venation_—The arrangement of veins in a leaf.
W
_Weigelia_—A genus of flowering shrubs allied to Honeysuckle.
_Whorl_—An arrangement of leaves or parts of the flower in rings.
_Wort_—Sweet unfermented new beer.
Y
_Yeast_—A unicellular plant that sets up fermentation under certain
conditions.
The Gresham Press,
UNWIN BROTHERS,
WOKING AND LONDON.
Transcriber’s notes
The text contains some inconsistencies in the usage of hyphens. Only
those have been corrected where the majority was spelled otherwise. All
corrections made are listed below.
To represent formatting the following conventions are used:
_word_ means that “word” is in italics;
+word+ means that “word” is in small capitals;
=word= means that “word” is in bold.
The asterism (⁂) on page 8 should be inverted, but this was not
possible to achieve since no such symbol exists.
Corrections
Page 20 In the list of illustrations hyphens removed from
“MONO-COTYLEDON” and “DI-COTYLEDON”, to match the captions of the
illustrations;
Page 21 In the list of illustrations “WHITE LILY PISTIL” changed
to “WHITE-LILY PISTIL” and “POLLEN-TUBE” changed to “POLLEN TUBE”,
to match the captions of the illustrations;
Page 22 In the list of illustrations “DIAGRAM OF TRANSFUSION” changed
to “TRANSFUSION DIAGRAM”, to match the caption of the illustration;
Page 22 In the list of illustrations “FLAVA” added behind “SARRACENIA”,
to match the caption of the illustration;
Page 42 “Another of these perching-plants is _Tillandsia Usnoides_”
changed to “Another of these perching-plants is _Tillandsia
Usneoides_”;
Page 62 “aërial” in “send down slender aërial roots” changed to
“aerial”, to match the spelling in the rest of the text;
Page 69 In “We may look upon the earth as being a sort of store-house”,
“store-house” changed to “storehouse” to match the spelling in the
rest of the text;
Page 100 In “in a skeleton leaf, the mid-rib”, “mid-rib” changed to
“midrib”, to match the spelling in the rest of the text;
Page 102 one occurrence of “called” removed from “belonging to this
great division are called called dicotyledons”;
Page 136 “to render the bud waterpoof” changed to “to render the bud
waterproof”;
Page 138 In “wood-sorrel is rolled into a spiral”, “wood-sorrel” is
changed to “woodsorrel”, to match the spelling in the rest of the
text;
Page 159 In “resembling the pine-apple plant”, the hyphen is removed
from “pine-apple”, to match the spelling in the rest of the text;
Page 202 “so that at length the seed-coats” changed to “so that at
length the seed-coat”;
Page 223 “PINE CONES” in the caption of the illustration, change to
“PINE-CONES” (in the list of illustrations too) to match the spelling
in the rest of the text and “fir-cones”;
Page 232 “have seeds with wings lightly twisted” changed to “have seeds
with wings slightly twisted”;
Page 238 “COCOS DE MER” in the caption of the illustration is
hyphenated (in the list of illustrations too) to match the spelling
in the rest of the text;
Page 246 “ivy-leafed toadflax” changed to “ivy-leafed toad-flax” to
match the spelling in the rest of the text;
Page 263 “the little epiphyte (mentioned in our first chapter),
_Tillandsia usnoides_” changed to “the little epiphyte (mentioned
in our first chapter), _Tillandsia usneoides_”;
Page 263 “by decomposing the carbon dioxide” changed to “by decomposing
the carbon-dioxide” to match the spelling in the rest of the text;
Page 280 “absorbs this carbon dioxide and effects” changed to “absorbs
this carbon-dioxide and effects” to match the spelling in the rest
of the text;
Page 337 “into technical phraseology these defininition” changed to
“into technical phraseology these definitions”;
Page 340 comma after “tuberous Umbelliferæ, earthnut” changed to
period;
Page 348 period added after “flowering plants and shrubs”.
*** END OF THE PROJECT GUTENBERG EBOOK GLIMPSES INTO PLANT-LIFE ***
Updated editions will replace the previous one—the old editions will
be renamed.
Creating the works from print editions not protected by U.S. copyright
law means that no one owns a United States copyright in these works,
so the Foundation (and you!) can copy and distribute it in the United
States without permission and without paying copyright
royalties. Special rules, set forth in the General Terms of Use part
of this license, apply to copying and distributing Project
Gutenberg™ electronic works to protect the PROJECT GUTENBERG™
concept and trademark. Project Gutenberg is a registered trademark,
and may not be used if you charge for an eBook, except by following
the terms of the trademark license, including paying royalties for use
of the Project Gutenberg trademark. If you do not charge anything for
copies of this eBook, complying with the trademark license is very
easy. You may use this eBook for nearly any purpose such as creation
of derivative works, reports, performances and research. Project
Gutenberg eBooks may be modified and printed and given away—you may
do practically ANYTHING in the United States with eBooks not protected
by U.S. copyright law. Redistribution is subject to the trademark
license, especially commercial redistribution.
START: FULL LICENSE
THE FULL PROJECT GUTENBERG™ LICENSE
PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK
To protect the Project Gutenberg™ mission of promoting the free
distribution of electronic works, by using or distributing this work
(or any other work associated in any way with the phrase “Project
Gutenberg”), you agree to comply with all the terms of the Full
Project Gutenberg License available with this file or online at
www.gutenberg.org/license.
Section 1. General Terms of Use and Redistributing Project Gutenberg
electronic works
1.A. By reading or using any part of this Project Gutenberg
electronic work, you indicate that you have read, understand, agree to
and accept all the terms of this license and intellectual property
(trademark/copyright) agreement. If you do not agree to abide by all
the terms of this agreement, you must cease using and return or
destroy all copies of Project Gutenberg electronic works in your
possession. If you paid a fee for obtaining a copy of or access to a
Project Gutenberg electronic work and you do not agree to be bound
by the terms of this agreement, you may obtain a refund from the person
or entity to whom you paid the fee as set forth in paragraph 1.E.8.
1.B. “Project Gutenberg” is a registered trademark. It may only be
used on or associated in any way with an electronic work by people who
agree to be bound by the terms of this agreement. There are a few
things that you can do with most Project Gutenberg electronic works
even without complying with the full terms of this agreement. See
paragraph 1.C below. There are a lot of things you can do with Project
Gutenberg electronic works if you follow the terms of this
agreement and help preserve free future access to Project Gutenberg
electronic works. See paragraph 1.E below.
1.C. The Project Gutenberg Literary Archive Foundation (“the
Foundation” or PGLAF), owns a compilation copyright in the collection
of Project Gutenberg electronic works. Nearly all the individual
works in the collection are in the public domain in the United
States. If an individual work is unprotected by copyright law in the
United States and you are located in the United States, we do not
claim a right to prevent you from copying, distributing, performing,
displaying or creating derivative works based on the work as long as
all references to Project Gutenberg are removed. Of course, we hope
that you will support the Project Gutenberg mission of promoting
free access to electronic works by freely sharing Project Gutenberg
works in compliance with the terms of this agreement for keeping the
Project Gutenberg name associated with the work. You can easily
comply with the terms of this agreement by keeping this work in the
same format with its attached full Project Gutenberg License when
you share it without charge with others.
1.D. The copyright laws of the place where you are located also govern
what you can do with this work. Copyright laws in most countries are
in a constant state of change. If you are outside the United States,
check the laws of your country in addition to the terms of this
agreement before downloading, copying, displaying, performing,
distributing or creating derivative works based on this work or any
other Project Gutenberg work. The Foundation makes no
representations concerning the copyright status of any work in any
country other than the United States.
1.E. Unless you have removed all references to Project Gutenberg:
1.E.1. The following sentence, with active links to, or other
immediate access to, the full Project Gutenberg License must appear
prominently whenever any copy of a Project Gutenberg work (any work
on which the phrase “Project Gutenberg” appears, or with which the
phrase “Project Gutenberg” is associated) is accessed, displayed,
performed, viewed, copied or distributed:
This eBook is for the use of anyone anywhere in the United States and most
other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg™ License included with this eBook or online
at www.gutenberg.org. If you
are not located in the United States, you will have to check the laws
of the country where you are located before using this eBook.
1.E.2. If an individual Project Gutenberg electronic work is
derived from texts not protected by U.S. copyright law (does not
contain a notice indicating that it is posted with permission of the
copyright holder), the work can be copied and distributed to anyone in
the United States without paying any fees or charges. If you are
redistributing or providing access to a work with the phrase “Project
Gutenberg” associated with or appearing on the work, you must comply
either with the requirements of paragraphs 1.E.1 through 1.E.7 or
obtain permission for the use of the work and the Project Gutenberg
trademark as set forth in paragraphs 1.E.8 or 1.E.9.
1.E.3. If an individual Project Gutenberg electronic work is posted
with the permission of the copyright holder, your use and distribution
must comply with both paragraphs 1.E.1 through 1.E.7 and any
additional terms imposed by the copyright holder. Additional terms
will be linked to the Project Gutenberg License for all works
posted with the permission of the copyright holder found at the
beginning of this work.
1.E.4. Do not unlink or detach or remove the full Project Gutenberg
License terms from this work, or any files containing a part of this
work or any other work associated with Project Gutenberg.
1.E.5. Do not copy, display, perform, distribute or redistribute this
electronic work, or any part of this electronic work, without
prominently displaying the sentence set forth in paragraph 1.E.1 with
active links or immediate access to the full terms of the Project
Gutenberg License.
1.E.6. You may convert to and distribute this work in any binary,
compressed, marked up, nonproprietary or proprietary form, including
any word processing or hypertext form. However, if you provide access
to or distribute copies of a Project Gutenberg work in a format
other than “Plain Vanilla ASCII” or other format used in the official
version posted on the official Project Gutenberg website
(www.gutenberg.org), you must, at no additional cost, fee or expense
to the user, provide a copy, a means of exporting a copy, or a means
of obtaining a copy upon request, of the work in its original “Plain
Vanilla ASCII” or other form. Any alternate format must include the
full Project Gutenberg License as specified in paragraph 1.E.1.
1.E.7. Do not charge a fee for access to, viewing, displaying,
performing, copying or distributing any Project Gutenberg works
unless you comply with paragraph 1.E.8 or 1.E.9.
1.E.8. You may charge a reasonable fee for copies of or providing
access to or distributing Project Gutenberg electronic works
provided that:
• You pay a royalty fee of 20% of the gross profits you derive from
the use of Project Gutenberg works calculated using the method
you already use to calculate your applicable taxes. The fee is owed
to the owner of the Project Gutenberg trademark, but he has
agreed to donate royalties under this paragraph to the Project
Gutenberg Literary Archive Foundation. Royalty payments must be paid
within 60 days following each date on which you prepare (or are
legally required to prepare) your periodic tax returns. Royalty
payments should be clearly marked as such and sent to the Project
Gutenberg Literary Archive Foundation at the address specified in
Section 4, “Information about donations to the Project Gutenberg
Literary Archive Foundation.”
• You provide a full refund of any money paid by a user who notifies
you in writing (or by e-mail) within 30 days of receipt that s/he
does not agree to the terms of the full Project Gutenberg™
License. You must require such a user to return or destroy all
copies of the works possessed in a physical medium and discontinue
all use of and all access to other copies of Project Gutenberg™
works.
• You provide, in accordance with paragraph 1.F.3, a full refund of
any money paid for a work or a replacement copy, if a defect in the
electronic work is discovered and reported to you within 90 days of
receipt of the work.
• You comply with all other terms of this agreement for free
distribution of Project Gutenberg™ works.
1.E.9. If you wish to charge a fee or distribute a Project
Gutenberg™ electronic work or group of works on different terms than
are set forth in this agreement, you must obtain permission in writing
from the Project Gutenberg Literary Archive Foundation, the manager of
the Project Gutenberg™ trademark. Contact the Foundation as set
forth in Section 3 below.
1.F.
1.F.1. Project Gutenberg volunteers and employees expend considerable
effort to identify, do copyright research on, transcribe and proofread
works not protected by U.S. copyright law in creating the Project
Gutenberg™ collection. Despite these efforts, Project Gutenberg™
electronic works, and the medium on which they may be stored, may
contain “Defects,” such as, but not limited to, incomplete, inaccurate
or corrupt data, transcription errors, a copyright or other
intellectual property infringement, a defective or damaged disk or
other medium, a computer virus, or computer codes that damage or
cannot be read by your equipment.
1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right
of Replacement or Refund” described in paragraph 1.F.3, the Project
Gutenberg Literary Archive Foundation, the owner of the Project
Gutenberg™ trademark, and any other party distributing a Project
Gutenberg™ electronic work under this agreement, disclaim all
liability to you for damages, costs and expenses, including legal
fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT
LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE
PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE
TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE
LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR
INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH
DAMAGE.
1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a
defect in this electronic work within 90 days of receiving it, you can
receive a refund of the money (if any) you paid for it by sending a
written explanation to the person you received the work from. If you
received the work on a physical medium, you must return the medium
with your written explanation. The person or entity that provided you
with the defective work may elect to provide a replacement copy in
lieu of a refund. If you received the work electronically, the person
or entity providing it to you may choose to give you a second
opportunity to receive the work electronically in lieu of a refund. If
the second copy is also defective, you may demand a refund in writing
without further opportunities to fix the problem.
1.F.4. Except for the limited right of replacement or refund set forth
in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO
OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE.
1.F.5. Some states do not allow disclaimers of certain implied
warranties or the exclusion or limitation of certain types of
damages. If any disclaimer or limitation set forth in this agreement
violates the law of the state applicable to this agreement, the
agreement shall be interpreted to make the maximum disclaimer or
limitation permitted by the applicable state law. The invalidity or
unenforceability of any provision of this agreement shall not void the
remaining provisions.
1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the
trademark owner, any agent or employee of the Foundation, anyone
providing copies of Project Gutenberg™ electronic works in
accordance with this agreement, and any volunteers associated with the
production, promotion and distribution of Project Gutenberg™
electronic works, harmless from all liability, costs and expenses,
including legal fees, that arise directly or indirectly from any of
the following which you do or cause to occur: (a) distribution of this
or any Project Gutenberg work, (b) alteration, modification, or
additions or deletions to any Project Gutenberg work, and (c) any
Defect you cause.
Section 2. Information about the Mission of Project Gutenberg
Project Gutenberg is synonymous with the free distribution of
electronic works in formats readable by the widest variety of
computers including obsolete, old, middle-aged and new computers. It
exists because of the efforts of hundreds of volunteers and donations
from people in all walks of life.
Volunteers and financial support to provide volunteers with the
assistance they need are critical to reaching Project Gutenberg’s
goals and ensuring that the Project Gutenberg collection will
remain freely available for generations to come. In 2001, the Project
Gutenberg Literary Archive Foundation was created to provide a secure
and permanent future for Project Gutenberg and future
generations. To learn more about the Project Gutenberg Literary
Archive Foundation and how your efforts and donations can help, see
Sections 3 and 4 and the Foundation information page at www.gutenberg.org.
Section 3. Information about the Project Gutenberg Literary Archive Foundation
The Project Gutenberg Literary Archive Foundation is a non-profit
501(c)(3) educational corporation organized under the laws of the
state of Mississippi and granted tax exempt status by the Internal
Revenue Service. The Foundation’s EIN or federal tax identification
number is 64-6221541. Contributions to the Project Gutenberg Literary
Archive Foundation are tax deductible to the full extent permitted by
U.S. federal laws and your state’s laws.
The Foundation’s business office is located at 41 Watchung Plaza #516,
Montclair NJ 07042, USA, +1 (862) 621-9288. Email contact links and up
to date contact information can be found at the Foundation’s website
and official page at www.gutenberg.org/contact
Section 4. Information about Donations to the Project Gutenberg
Literary Archive Foundation
Project Gutenberg™ depends upon and cannot survive without widespread
public support and donations to carry out its mission of
increasing the number of public domain and licensed works that can be
freely distributed in machine-readable form accessible by the widest
array of equipment including outdated equipment. Many small donations
($1 to $5,000) are particularly important to maintaining tax exempt
status with the IRS.
The Foundation is committed to complying with the laws regulating
charities and charitable donations in all 50 states of the United
States. Compliance requirements are not uniform and it takes a
considerable effort, much paperwork and many fees to meet and keep up
with these requirements. We do not solicit donations in locations
where we have not received written confirmation of compliance. To SEND
DONATIONS or determine the status of compliance for any particular state
visit www.gutenberg.org/donate.
While we cannot and do not solicit contributions from states where we
have not met the solicitation requirements, we know of no prohibition
against accepting unsolicited donations from donors in such states who
approach us with offers to donate.
International donations are gratefully accepted, but we cannot make
any statements concerning tax treatment of donations received from
outside the United States. U.S. laws alone swamp our small staff.
Please check the Project Gutenberg web pages for current donation
methods and addresses. Donations are accepted in a number of other
ways including checks, online payments and credit card donations. To
donate, please visit: www.gutenberg.org/donate.
Section 5. General Information About Project Gutenberg electronic works
Professor Michael S. Hart was the originator of the Project
Gutenberg concept of a library of electronic works that could be
freely shared with anyone. For forty years, he produced and
distributed Project Gutenberg eBooks with only a loose network of
volunteer support.
Project Gutenberg eBooks are often created from several printed
editions, all of which are confirmed as not protected by copyright in
the U.S. unless a copyright notice is included. Thus, we do not
necessarily keep eBooks in compliance with any particular paper
edition.
Most people start at our website which has the main PG search
facility: www.gutenberg.org.
This website includes information about Project Gutenberg,
including how to make donations to the Project Gutenberg Literary
Archive Foundation, how to help produce our new eBooks, and how to
subscribe to our email newsletter to hear about new eBooks.
