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Full text of "The study of plant life"

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Study o 

PLANT LIFE 

KdLC.STOPES D.Sc 



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BLACK1E AND 5ON LIMIIXI 



LIBRARY 



UNIVERSITY OF CALIFORNIA. 



_. BIOLOGY 

Class x , LIBRARY 



THE STUDY OF PLANT LIFE 



First Impression October 1906. 

Second Impression February 1907. 

Second Edition 1910. 



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ANCIENT PLANTS 

BEING A SIMPLE ACCOUNT OF THE 
PAST VEGETATION OF THE EARTH 
AND OF THE RECENT IMPORTANT 
DISCOVERIES MADE IN THIS REALM 
OF NATURE STUDY 

Illustrated. Demy 8vo, 4s. 6d. net 

" Miss Stopes's book is an enterprising and able attempt to popu- 
larize a difficult subject. The really keen student will undoubtedly 
be stimulated to pursue the study of fossil plants further, and even 
those who are not students will get some new ideas and derive a 
certain amount of interest from a book which is sometimes brilliant 
but never dull." Nature. 

" Dr. Marie Stopes has made a name for herself in this special line. 
Anyone who takes an intelligent interest in the subject cannot fail to be 
charmed with the pleasant manner in which Dr. Stopes conveys her 
information." Athenaeum. 



PLATE I. 




THE STUDY OF 

PLANT LIFE 



BY 



M. C. STOPES 

\\ 

D.Sc.(LoND.), PH.D.(MUNICH), F.L.S. 

Lecturer in Palseobotany at the University of Manchester 



Second Bdition 



* * 



LONDON: BLACKIE & SON, LIMITED 

NEW YORK: D. VAN NOSTRAND COMPANY 

1910 



BIOLOGY 

LIBRARY 

G 



PRINTED AT 

THE VILLAFIELD PRESS 

GLASGOW 



PREFACE 

As a result of the present efforts to raise the standard of education in 
this country, many different " Methods of Teaching " are receiving 
our grave consideration. So insistent are their advocates, that we 
stand in some danger of forgetting that learning, rather than 
teaching, is the essential factor in education. It is not the know- 
ledge given us ready-made by the teacher, but that which we 
learn, acquiring it by our own efforts, which enters into our being 
and becomes a lasting possession. 

Therefore this little book does not pretend so much to teach as 
to act as a guide along the road for those who desire to learn 
something about the plants around them ; hence it points out how 
much they can easily see for themselves of the wonderful life and 
work of the silent plants. 

It is planned for children, whose quick sympathies are more 
readily drawn towards the life of things than to the dry facts of 
morphology or classification. Its " Leitmotif" is therefore the story 
of life, and those of its activities which find expression in the plant 
world. Perhaps it may serve to awaken interest in some older 
people who have not yet been initiated into these mysteries. 

As is inevitable, most of the actual facts in this book are already 
the common property of botanists, though some of the suggested 
work, such as the mapping, is only now being adopted by the 
Universities. 

The most interesting subjects are often left out of the more 
elementary books, or even if given are frequently set forth in 
such a lifeless and pedantic fashion, that little real interest or 
understanding has been awakened in the young student. The 
present work attempts to avoid the time-worn methods of arranging 
the subject. Children generally know more about the behaviour 

vil 



223979 



viii. PREFACE 



of animals than that of plants (being themselves animals and fre- 
quently having kittens or other pets) j hence, the parallels between 
the life-functions of plants and those of animals are pointed out 
whenever possible. Once the idea of their " livingness " has been 
fully realised, it is time to go on to the study of the details of the 
plant's body, and then to the communities of plants which grow 
together. In this way the child can work out from its own obser- 
vations a complete and logical idea of the living plant, instead of 
having merely acquired a detailed but fruitless knowledge of barren 
facts. 

To burden a child's memory with long names is not only useless 
but harmful, therefore an effort has been made to use only short 
and simple words. A few scientific terms are introduced where 
they are really of value as describing things which are not generally 
noticed, and so do not come into the usual English vocabulary. 
In such cases it is far better for the child to learn the correct 
scientific name than to be provided with a clumsy translation 
consisting of several English words which can never give the 
precise meaning. 

The use of a microscope is not to be recommended for those 
beginning the study of plant life, and the chapters have been planned 
so that no greater magnification than that of a good hand lens will 
be needed. This, however, makes it difficult to explain the life 
histories of the fern and other primitive plants; hence in the chapters 
bearing on them stress has not been laid on many of the funda- 
mental points which are only to be seen with the microscope, but 
on those facts which can be observed without it. 

The chapters on the families of plants attempt to bring out the 
reasons for the separations of the few great groups only ; detailed 
classification of the flowering plants has so long been considered the 
chief part of botany, that it is to be found in nearly every school- 
book on the subject. 

If this book should be used as the text-book for young children, 
the teacher will probably find it necessary to enlarge on the instruc- 
tions for the work suggested in the last three chapters, which 
were added chiefly for the guidance of those who may assist the 



PREFACE 



youthful students in carrying out the practical work therein out- 
lined. 

I sincerely hope that those who wish to learn, and are prepared 
to study the plants themselves, may get some help from this little 
guide-book. 

M. C. STOPES. 

The University, Manchester, 
July i go 6. 



PREFACE TO SECOND EDITION 

THE public and the critics have been so kind to the first edition of this 
book that I am encouraged to offer them a second. There are no 
considerable changes in it, but I have profited by some suggestions 
regarding points of detail which several friends have been good enough 
to offer, and hope that the book has now fewer blemishes, and will be 
more useful. In Chapter XXXIV. two interesting photographs of 
drowning trees have been added, which illustrate a problem in Ecology 
less generally studied than its converse. 

It has been very pleasant to hear from many teachers, some in distant 
parts of the earth, that the book has been useful to them, and I hope 
they will continue to allow me the privilege of their criticism or 
appreciation. 

M. C. STOPES 

The University, Manchester, 
October igio. 



ACKNOWLEDGMENT 

FOR the right to reproduce the photographs I am much indebted 
to the following gentlemen, to whom I express my warm thanks : 
viz. to the Rev. J. S. Lea, of Kirkby Lonsdale, for Plate VII. and 
fig. 149 ; to Prof. F. W. Oliver, of London, for Plate VI. ; to 
Dr. O. V. Darbishire, of Manchester, for Plate IV. and fig. i 30; 
to Prof. K. Fujii, of Tokio, for Plate III.; to Dr. F. F. Blackman, 
of Cambridge, for fig. 144; to Mr. Crump, of Halifax, for fig. 140 ; 
to Mr. R. Welch, of Belfast, for Plates I. and V., and fig. 138 ; 
to Dr. H. Bassett for figs. I 54 and 155. 

To Dr. W. E. Hoyle of Manchester, and to Miss Mary 
McNicol, B.Sc., I am also much indebted for their kindness in 
reading the proof-sheets. 

I have drawn all the text illustrations specially for this book. 

M. C S. 



CONTENTS 

PART I. 
THE LIFE OF THE PLANT 

CHAP. PAGE 

I. Introductory - I 

II. Signs of Life - 4 

III. Seeds and Seedlings - 8 

IV. Food Materials of the Older Plant i. In the Soil - 14 
V. Food Materials of the Older Plant 2. In the Air - 18 

VI. The Food Manufactured by the Plant 23 

VII. The Circulation of Water 28 

VIII. Light and its Influences 35 

IX. Growth in Seedlings - 40 

X. Movement - 45 

Summary of Part I. - 49 

PART II. 
THE PARTS OF A PLANT'S BODY, AND THEIR USES 

XI. Roots - 53 

XII. Stems - 58 

XIII. Leaves 64 

XIV. Buds - 72 
XV. Flowers 78 

XVI. Fruits and Seeds 86 

XVII. The Tissues Building up the Plant Body - 92 

xi 



xii. CONTENTS 



PART III. 
SPECIALISATION IN PLANTS 

CHAP. 

XVIII. For Protection against Loss of Water 

XIX. Specialisation for Climbing- 

XX. Parasites 

XXI. Plants which eat Insects - 

XXII. Flower Structures in Relation to Insects - 

PART IV. 
THE FIVE GREAT CLASSES OF PLANTS 

XXIII. Flowering Plants .... 

XXIV. The Pine-Tree Family 

XXV. Ferns and their Relatives ... 
XXVI. Mosses and their Relatives - 
XXVII. Algae and Fungi .... 

PART V. 
PLANTS IN THEIR HOMES 

XXVIII. Hedges and Ditches 
XXIX. Moorland .... 

XXX. Ponds - . 

XXXI. Along the Shore .... 
XXXII. In the Sea - - 

XXXIII. Plants of Long Ago - 

XXXIV. Physical Geography and Plants 
XXXV. Plant Maps - 

XXXVI. Excursions and Collecting - 
Index ... 



(C260) 



PART I. 

THE LIFE OF THE PLANT 

CHAPTER I. 
INTRODUCTORY 

MANY people do not realise that plants are alive. This 
mistake is due to the fact that plants are not so noisy 
and quick in their ways as animals, and therefore do 
not attract so much attention to themselves, their lives, 
and their occupations. 

When we look at a sunflower, surrounded by its 
leaves and standing still and upright in the sunlight, we 
do not realise at first that it is doing work ; we do not 
connect the idea of work with such a thing of beauty, 
but look on it as we should on a picture or a statue. 
Yet all the time that plant is not only living its own life, 
but is doing work of a kind which animals cannot do. 
Its green leaves in the light are manufacturing food for 
the whole plant out of such simple materials that an 
animal could not use them at all as food. Even its 
beautiful flower is creating and building up the seeds 
which will form the sunflowers of the future. All 
animals directly or indirectly make use of the work 
done by plants in manufacturing food, for they either 
live on plants themselves, or eat other animals which 
do so. 

Plants are living, and therefore require food of some 
kind as well as air and water in the same way, and for 
the same purposes as do animals. As a rule, we cannot 
see them breathing and eating, but that is because we do 
not look in the right way. In our study of plants we 
must first learn how to see and question them properly, 
and when we have done this they will show themselves 

t C 260 ) 1 B 



CHAP. I. 



to us and tell us stories of their lives which are quite as 
interesting as any animal stories. 

Now the sunflower we have just thought of is 
probably growing in a garden well looked after by 
a gardener, who sees that it gets all the light and water 
and just the kind of soil it needs. It is therefore pro- 
tected and cared for to a certain extent, but who looks 
after the wild plants which manage to grow everywhere ? 
These have not only their own lives to live, but by 
their own efforts must overcome difficulties which are 
not even felt by the cultivated ones. 

They succeed in a wonderful way, and r some plants 
manage to grow under very difficult conditions, even 
in places where they get no water for months under a 
burning sun, or in forests where the overshadowing 
trees cut off the light and rain, or under the water 
where they get no direct air. They have to do all the 
usual work of plants, and at the same time struggle 
against the hardships of their surroundings. They are 
like men fighting for their lives with one hand and 
doing a piece of work with the other. 

The result of this is that they sometimes make them- 
selves strange-looking objects, and in some plants which 
have had a very hard struggle it is difficult to know 
which part of the plant is which. Look, for example, 
at a Cactus (see fig. 48), which grows in the desert ; it 
appears to have neither stem nor leaves like an ordinary 
plant, and to consist merely of a roundish green mass 
covered with needle-like prickles. Yet when you come 
to study the Cactus you will find out that the thick, 
fleshy mass is really its stem, and the prickles its leaves 
which have taken on these strange shapes. By means 
of its unusual form the Cactus can live where our 
common plants would die of the dry heat in a day or 
two. The power plants have of changing their bodies 
so as to fit themselves to live under all kinds of 
conditions is one of the strongest proofs that they are 
alive. 



CHAP. I. INTRODUCTORY 



All the parts of plants have some special life-work, 
just as we have legs and arms for different purposes, 
and every part is formed in some way to suit the needs 
of the plant and help it to get on well in its home. 

The main thing to realise at the beginning of the study 
of plants is that they are living things, and therefore to 
try to discover the importance of the shape and arrange- 
ment of all their parts and their relation to the life of 
each plant as a whole. 

We will begin by looking carefully for all the signs of 
life in them, and noting how often these are the same as 
those of the animals, even though the whole plant-body 
is so different from that of an animal. 



CHAPTER II. 
SIGNS OF LIFE 

IF you were asked to give the signs of life in an 
animal, it is likely that you would think at once of its 
power of breathing, eating, growing, and moving. 

Now when we ask the same question about plants the 
answer does not appear to be quite so easy to find, because 
at first sight plants do not seem to do any of these things 
except the growing. However, the same answer would 
be quite correct for plants, as well as animals, for they 
are really able to breathe, eat, grow, and move ; all you 
have to do is to watch them in the right way to see that 
this is the case. 

We are not in the habit of treating dry seeds as 
though they were alive ; beans are stored away in sacks 
all the winter and may be left for months in dry cellars, 
and the precious seeds which will give us our beautiful 
flowers in the summer are put away in boxes through 
the winter. Yet you know that if you place seeds 
in the earth and keep them warm and moist, little 
plants will come up and will grow. What gives them the 
power of growth which is not possessed by the stones 
and earth around them ? Warmth and moisture alone 
could not put this power into the seeds when we planted 
them. This power, which only belongs to living things, 
was there all the time, but was lying asleep, shut in 
and protected so that it was not easily disturbed till 
suitable conditions made it time for it to wake. 

You know when you are asleep that you do not eat or 
run about, but simply lie still and breathe. This is 



CHAP. II. 



SIGNS OF LIFE 




what the seed was doing before the baby plant began to 
break through its protecting coat and show itself to the 
world as a living thing. 

Let us watch some of these young plants just waking 
up to activity, and see if we can find in them the four 
signs we take as being the tests of animal life. 

First let us see if we can show that they breathe. 

You know that when you breathe 
you take air into your lungs, use 
some of it, and give the rest out. 
You can show that plants also use 
up some part of the air. If you 
would actually prove this to your- 
self or anyone else, take some peas 
or beans, soak them in water, and 
leave them in damp sawdust for a 
day or two till the tiny plant has 
just begun to show. Then put 
them on wet blotting-paper in a 
jar which has a very well-fitting 
cork with no leakage, and through 
which a fine bent glass tube is 
fitted. Place a small tube of 
caustic potash in the jar. Then 
place the end of the bent tube in 
a dish of water, which acts better 
if you have dissolved some caustic 
potash in it (see fig. i) . Once it has 
begun to rise in the tube, mark the 
level of the water with a small 
label. If then you mark it daily 
the labels will show how much 
water has risen each day, and the amount of water 
rising in the tube shows us the amount of air which 
has been absorbed by the growing beans. 

This tells us, therefore, that air is absorbed by plants in 
the course of their growth. But there is another thing we 
must notice about breathing which is equally important. 




--2 



Fig. i. Jar (A) with well- 
fitting cork, in which young 
bean plants are growing. 
The tube leading from the 
jar dips into dish of water 
(s) which has risen to levels 
marked in the course of 
three days, (b) Small tube 
of caustic potash. 



SIGNS OF LIFE CHAP. II. 




You will find that you yourself, as well as all animals, 
not only use up a part of the air, but also give out 
a waste product which we call carbonic acid gas. 
You can see one of the characters of this gas from your 
lungs if you take a jar of lime water and breathe into it 
for some time. Compare this with a similar jar of lime- 
water through which ordinary air has been pumped at 
about the same rate for 
the same time, and you 
will see that the one 
you have breathed into 
has gone very much 
more cloudy-white than 
the other (see fig. 2). 
The cloudiness in jar A 
is caused by the waste 

gas (carbonic acid gas) Fig, 2. Jar A contains lime-water through 

which VOU breathe Out which human breath has passed. Jar B, 

j yuu Ui ccuiic yui, lime _ water through which ordinary air has 

and Which Combines been pumped for the same time. Note how 

with the lime in the JgftJJf 1 * * *" milky deposit * A 
lime - water to make 

solid grains of chalk. Fine white chalk grains always 
form in lime-water when this gas is present, so that a 
jar of clear lime-water is a very good test for the 
presence of the gas. 

The giving out of carbonic acid gas is one of the 
most characteristic things about animal breathing, and 
we can show that plants in breathing give out this gas 
too. 

To prove this, take another jar with a well-fitting cork, 
and put some beans and peas, which are just beginning 
to grow, into it, with a little damp blotting-paper to keep 
them sufficiently moist. Leave the jar closed for a day 
or two and then open it and quickly and gently pour in 
some lime-water. Put the lid on again at once and 
shake it up. You will find that the lime-water turns 
quite milky, showing that the same waste gas is given out 
by the plants as was given out in your own breath. 



CHAP. II. SIGNS OF LIFE 



These experiments show us that plants breathe in a 
part of the air, and also breathe out some of the same 
waste gas which is given off by animals in breathing. So 
that we have found that plants do breathe. 

Now to go to the other signs of life. I think you will 
hardly need to do any special experiment to show that 
seedlings grow into big plants, you must have seen it so 
often for yourself in the woods and fields and gardens. 

We have still to show that plants eat and move, but 
before we can do this properly, we must learn a little 
more about the parts of the bodies of the plants them- 
selves, for they have quite a different set of organs to 
those we are accustomed to in animals, and their way of 
eating is so different from that of animals that we cannot 
understand it immediately. 



CHAPTER III. 



SEEDS AND SEEDLINGS 

IF we wish to follow the whole life of a plant, we cannot 
do better than begin by watching the baby plant 
" hatching " out from its seed at the beginning of its 
active life. 

There are many seeds which would be good to begin 
work on, any kind would be interesting, but it is best to 
use some nice big ones which allow us to see the parts 
easily. Good ones to choose would be broad beans or 
peas. Notice first the size and shape of the dry seed of 
the bean, make a drawing of it, and then place it in 
water. After a few hours you will see that the outside 
skin wrinkles up ; this is because the skin absorbs water 
and increases in size, and so becomes too big for the 
rest of the seed (see fig. 3, A, B). After the water has 

soaked right 
into the sub- 
stance of the 
seed you will 
find that the 
outer skin fits 
again and is 
once more 
smooth, and 
that the whole 
seed is larger 
than it was before it was soaked (see fig. 3, C). 

Take one of these soaked beans and examine its 
structure. Notice the black mark where it was attached 
to the parent pod, and the little triangular ridge pointing 




Fig. 3. A single Bean seed, A dry ; B half soaked, 
when the skin wrinkles ; C fully soaked and swollen. 



CHAP. III. 



SEEDS AND SEEDLINGS 



towards it (see fig. 4, A). Now carefully peel off the 
skin, noticing that there are two skins, an outer thick 
one and an inner thin one, which protect the parts 
within. When you have removed the skin, you will 
find that the inner portions of the seed split very readily 
into two thick fleshy parts, and that lying between 
them is a tiny young plant. Notice how this young 
plant is connected on either side with the fleshy parts, 
so that to separate them you must tear one side or the 
other as in fig. 4 B, where at (a) we see the scar left 
where the tiny plant (p] was torn from the side. The 

two big fleshy parts 
are really portions of 
the young plant, and 
are in fact its two first 
leaves, but they are 
very different from or- 
dinary leaves, and are 
packed with food sub- 
stances, and are called 
the cotyledons, or 
" nurse-leaves." Notice 
also the tiny root of 
the baby plant or em- 
bryo, as it is called ; it 
bends a little to the 

outer side, and fits into a kind of pocket in the skin of 
the coat. You can see the shape of the root even from 
the outside of the dry bean (see fig. 4, A (r) ). You will 
find in the pea, cucumber, and many other seeds, that 
there is also the tiny embryo with its two nurse leaves, 
the whole being protected by strong coats. The differ- 
ences between the bean, pea, and cucumber seeds are 
only in the details of shape and colour, not in the actual 
parts of the seed. 

In the case of maize and corn, however, you will find 
that the seed does not split into two equal parts like the 
bean, but that the young plant lies at one side of the 




B. 



Fig. 4. A, outside of Bean; (h] black 
scar showing where the bean was attached 
to the pod ; (r) ridge made by young root ; 
B, bean split open ; () nurse leaves ; (p) 
baby plant ; (a) scar where the baby plant 
was separated from the nurse leaf on that 
side. 



10 



SEEDS AND SEEDLINGS 



CHAP. III. 




.-.-*/&. 



Fig. 5. A, outside of 
Maize fruit, showing the 
embryo (e) on one side; 
B, sprouting plant, show- 
ing the root (r) and shoot 
(s) ; C, the same further 
grown. 



seed, and a solid white mass fills the rest of the space 
(see fig. 5). There are also differences in the seedlings 
which you will notice when they begin to grow. 

Now that you have ex- 
amined some seeds, you 
should start a number 
growing, so as to have 
plenty to watch. They 
will grow more quickly 
if you soak them in water 
for a night before you 
plant them in damp saw- 
dust, and keep them 
moist and fairly warm all 
the time. You should 
have a number of seeds 
of each kind planted to- 
gether to provide enough 
for you to dig up one of them every day and examine 
it fully, inside as well as out. Make a drawing of each 
one so that you will have a complete series of drawings 
showing how the young plants grow. This will kill 
them, so that you must leave at least one seedling 
which is never touched, 
and which you can 
watch all through its 
life. 

As the young plant 
grows, notice how it 
breaks away from the 
protection of its nurse 
leaves ; first the root 
comes out and bends 
downwards into the saw- 
dust (see fig. 6 A), then 
the little shoot which 
bends up into the air. 

Whichever way you plant the seeds you will find this 




Fig. 6. Growth of Bean seed- 
ling : A, the root only showing ; 
B, the root lengthening and shoot 
appearing. 




CHAP. III. 



SEEDS AND SEEDLINGS 



ii 



is always the case, for even if you start with the root 
pointing up, it will bend round and grow downwards 
while the shoot bends up (see p. 41). 

As the plant gets bigger, side roots grow out from 
the main one, and the little leaves of the shoot begin 
to open out the whole plant is 
growing (see fig. 7). 

Now we may perhaps begin 
to find out something about the 
question of feeding in plants. 
What are the nurse-leaves doing all 
the time the plant is growing ? You 
will find in the bean that the seed 
coats may split open a little, but 
that on the whole the cotyledons 
remain all the time enclosed in 
them, and attached to the young 
shoot (see fig. 7). Examine the nurse 
leaves of seedlings of different ages, 
and you will see that they are much 
less thick and fleshy in the older 
seedlings. As the plant gets bigger 
the nurse-leaves get thinner and 
less until they become merely dry 
shrivelled remnants. 

Now, what use could the cotyle- 
dons be if they only shrivel away? 

Take a freshly soaked seed and 
cut a thin slice of the nurse-leaves 
and drop it into a little solution of 
iodine ; * the tissue will go a violet 
blue colour. Then drop iodine on 
a piece of bread, a piece of potato, 
and some boiled rice, and you will find that they also 
go blue, or almost black. The food in the nurse-leaves 




Fig. 7. Later stage in 
the growth of Bean seed- 
ling ; side roots developed, 
and the shoot enlarged. 



* Get a chemist to make a solution of iodine and potassium iodide, 
which should be a bright, clear, orange colour. 



12 SEEDS AND SEEDLINGS CHAP. III. 

is in some ways the same as that in bread, potato, and 
rice, and in many other things we eat. 

The part of the food which goes blue with iodine is 
starchy and this blue colouring of starch with iodine is 
an easy and safe test for it. You will see the same 
colour if you take some ordinary laundry starch and stir 
it up with hot water and a little iodine. Look now at 
the corn seed ; the white solid mass in the seed con- 
tains starch, as you can prove with iodine, and although 
it is not in the cotyledon, yet it is quite near the young 
plant, which can get at it easily. 

We have found, therefore, that young plants have a 
store of food in their nurse-leaves, 01 near them in the seed, 
and that this food is the same as very much of our own 
food, that is, it is starch. There are other food sub- 
stances present, too, but they are more difficult to find. 
The seed, therefore, contains not only the young living 
plant itself, but also a storehouse of food for its use, and 
as the plant grows we see this store getting less and less 
in the shrivelling cotyledons. This shows that the 
young plant uses up this food in the course of its 
growth. 

But you must not forget that, although we find the 
young plants provided with food in this way, we have 
not yet settled the question of the food supply for all 
plants. As we see, the cotyledons shrivel up and are 
emptied of their store long before the plant is full 
grown. Remember that baby calves have milk for food, 
while old cows have grass. And when the store of food 
supplied in the seed is finished the older plants must 
find new supplies for themselves. 

In growing seedlings you must always keep them 
well supplied with water, the soil or sawdust in which 
they grow must be kept moist. If you take one out of 
the sawdust and try to grow it only in the air, you will 
find that it soon dies. Even for the seedling the store- 
house of food is not enough ; it requires to have water 
too. 



CHAP. III. 



SEEDS AND SEEDLINGS 



You can keep seedlings growing 
if you place them in glass jars so 
that their roots are in water, or 
even in closed glass jars stand- 
ing over water, so that the air is 
thoroughly moist. You will then 
be able to see very well numbers 
of fine white hairs on the roots 
(see fig. 8). These hairs are very 
important and absorb the water 
which keeps the whole plant 
moist. 

You have now seen that seed- 
lings require water for their life 
just as animals do; and also that 
young plants are provided by their 
parents with a store of food which 
is largely starch, and which they 
use up during their early growth. 



quite well, however, 




Fig. 8. Maize seedlings 
growing enclosed in damp 
air, supported on a wire 
stand over dish of water 
so that their roots do not 
touch it, but grow in the 
air. Notice the " root hairs " 
growing out from the roots. 



CHAPTER IV. 
FOOD MATERIALS OF THE OLDER PLANT 

(l) IN THE SOIL 

As we have just seen, young seedlings are supplied 
with stores of food, starch, and other things, which are 
packed in their cotyledons and are used up by them as 
they grow. But we also saw that as the plant gets 
older these stores get emptier, and finally the nurse 
leaves shrivel up entirely when their contents are ex- 
hausted. All the same, however, the plant continues 
to grow. Surely it cannot do this on nothing, any more 
than an animal could ? When the young calves cease to 
be fed with milk, their food changes, and they begin to 
eat grass ; this gives them individually more work, for 
grass is not a " prepared food " like milk. Very much 
the same thing happens with seedlings. Their prepared 
food supply gets used up, and they must find food for 
themselves. Where do they find it? 

When you remember the fine hairs on the young 
parts of roots which absorb water from the soil or saw- 
dust, it is quite natural to think at once of the soil as 
a possible place for them to find their food ; and, in- 
deed, this is partly the case. The water in the soil is 
not perfectly pure, for there are many different " salts " 
dissolved in it. By " salts " one does not mean only 
table salt, but also any kind of mineral in solution, such 
as salts of iron or portions of chalk or limestone, or even 
some of the minerals which make up granite. These 
may all be dissolved in rain-water just as sugar is dis- 
solved in your tea, and so spread equally through it. 



CHAP IV. FOOD MATERIALS IN THE SOIL 




Fig. 9. Root hairs growing among soil particles. 



As the water enters the roots of plants through the 
hairs, these dissolved salts come in with it, and so get 

distributed 
over the 
whole plant. 
The root 
hairs can- 
not " eat " 
particles of 
soil, but 
they twine 
in among 

the fine grains and absorb the little films of water which 
cling to them. 

You can find out some of the importance of these 
mineral salts in the life of the plant, if you do the 
following experiment. 

Take several seedlings which have already grown 
enough to have nearly exhausted the supply of food in 
their cotyledons. These you must grow in jars of pure 
distilled water, to which you have added certain salts 
which have been found to be the important ones in the 
soil water and plant food. By giving the plant nothing 
but these salts and distilled water you know just what 
it gets. Distilled water is made by catching and con- 
densing steam, and it has no salts dissolved in it ; while 
ordinary tap water has run off some mountain side or 
risen in some spring from the rocks, and it has many 
salts in it already, so that it is useless for this experiment. 
Take three big glass jars, each with one litre of distilled 
water, and label them A, B, and C. Into A put nothing 
further, into B put the following salts, which have been 
weighed out carefully either by you or by a chemist : 
Potassium nitrate - - i gramme 

Calcium sulphate - - J 

Sodium chloride - 

Magnesium sulphate - 

Calcium phosphate 



i6 



FOOD MATERIALS IN THE SOIL CHAP. IV. 




then add to C all these salts, and also one or two drops 
of a dilute solution of iron chloride. 

Into the jars fit corks which are split, with a hole in 
the centre, and pack a plant into each with the part of the 
stem between the corks wrapped 
round with cotton wool (see fig. 10), 
and so fix the plant that its roots 
are in the solution and its stem 
and leaves in the air* (see fig. n). 
Wrap black cotton or paper round 
the jars so as to keep the roots 
dark as they would be in the soil. 

Do not use too small vessels; 
in fact, if you had bigger jars and 
took double quantities of every- 
thing it would be better. 

You may make the experiment 
more complete by preparing a 
whole series of solutions with one 
of the salts left out each time. In 
this way you would be able to see the effect of the 
different elements on the growth of the plants, and you 
would find nitrates are very important. Put a plant, 
similar to the one you are experimenting with, into a 
pot of soil or the garden, and keep it well watered. 
This is called the " control plant." 

Very soon you will find that the plant in jar A (the 
one with only distilled water) is not growing so fast 
as the others, and after a time will die off completely. 
The one in jar C with all the salts, on the other hand, 
should grow quite as well as the control plant in the 
garden, which you should take as the standard. 

The plant in jar B, when it has everything but iron, 
should act in a curious manner. At first it should 
grow all right and outlive the one in distilled water, 



Fig. 10. Plant packed in 
split cork, (/t) Hole in cork ; 
(c) cotton-wool packing the 
stem. 



* Weigh the plant, which you are putting in jar C, carefully, and keep 
a record of its weight for future use (see p. 18). 



CHAP. IV. FOOD MATERIALS IN THE SOIL 






but after a time its leaves should get paler, till the new 

ones formed are 
quite yellow in- 
stead of green, 
and soon after 
this the plant 
will die. If, how- 
ever, you add 
two drops of the 
iron solution 
before it dies, it 
may recover, 
become green 
again, and go on 
living. It turned 
a whitish yellow 
colour because 
there was no iron 

Fig. ii. Three jars in which seedlings of the m ^8 su Ppty of 

same age are growing ; A, in distilled water ; B, salts and Water. 

in the food solution without iron; and C, in the T , , 

complete food solution. JUSt as When 

people get pale 

and white the doctor orders them iron, so it is necessary 
for plants to have iron when they begin to lose their 
green colour. Later on you will find how very important 
the green colour is, for without it they cannot grow 
(see Chap. VI.),* 

From these experiments you see that it is not the soil 
which is necessary to the plants, but that certain salts in 
solution in the water held by the soil particles are very 
important. When all the salts are present in the water, 
as was the case in jar C, the plant can grow just as well 
as one in the soil; but when it has not these salts it 
must die. The salts in solution, therefore, must be a 
very important part of the food. Are they the only food 
the plant gets ? 

* This experiment is sometimes difficult to manage successfully, though 
it appears so simple. Great care should be taken not to overdose the 
plant with iron. 

( C 260 ) C 



CHAPTER V. 

FOOD MATERIALS OF THE OLDER PLANT 

(2) IN THE AIR 

THE experiments you have just done show that plants 
absolutely require the mineral salts dissolved in the 
water of the soil or of their food solutions. Yet although 
these salts are so necessary, they do not use a large 
quantity of them, as you may prove by taking the 
solution C, which is left after the plant has grown 
in it, and slowly drying off all the water (taking care 
not to destroy a part of the salt crystals) by gentle 
heat, and then weighing this dry salt, and comparing its 
weight with that of the salts you put into C. You will 
find that the growing plant has only removed a small 
quantity of the salts. Yet the plant should have grown 
to some considerable size. Of course, the water itself 
goes into the plant tissues, but you can drive this off by 
gentle heat. Before drying it, however, cut off a part of 
the plant which is equal in weight to the weight of the 
young plant you put into the food solution at first (see 
p. 16), so that you have only to deal with the amount of 
its growth while using the food solution. Then if you 
weigh the fully dried plant, you get the weight of the 
solid structure added to its body while it was growing 
in the food solution, and you will find that this is much 
heavier than the amount of the salts it used during its 
growth. 

What is this extra substance? 

Now let us examine the dried plant more carefully. 
Heat it on an open dish, and you will find that it goes 



CHAP. V. FOOD MATERIALS IN THE AIR 19 

black and chars, very like the charred wood on a fire or 
specially prepared charcoal. The black charcoal is well 
known to consist chiefly of carbon, and so does this 
black plant-ash. You know that charcoal can burn, and 
so will this charred plant if you heat it more strongly. 
Although you can burn the carbon (that is, you can 
make it combine with oxygen gas and go off in an in- 
visible form), yet you cannot absolutely destroy it. Like 
all elements it is not to be made or destroyed by us, nor 
can the plant make carbon for itself. 

If you examine the list of substances you put into the 
food solution once more, you will find that carbon is not 
among them, nor is it contained in any of them. 

Carbon, then, is the extra substance which makes the 
weight of the plant greater than that of the salts used from 
its food solution. 

Where does the plant find this carbon? 

You may know that there are three chief gases in the 
air: oxygen and nitrogen, which are the important 
parts for our breathing, and a little carbonic acid gas, 
which you may remember is breathed out by animals 
and plants (see p. 6), and is made of carbon joined with 
oxygen. As there was no carbon in the food solution, 
and the plant was surrounded by air containing carbon 
and oxygen in the invisible form of gas, the idea is sug- 
gested that perhaps it is from the air that the plant gets 
its carbon. Now let us see if this is true by trying the 
effect of removing the carbonic acid gas from the air in 
which the plant is growing. 

To do this we must set up an apparatus which will 
allow only air freed from carbonic acid gas to surround 
the plant. Such an apparatus is shown in the figure 12. 
The plant is grown in the closed bell jar D, which 
stands over the dish C filled with lime-water, which 
prevents carbonic acid gas entering through the cracks 
between the foot of the jar and the table. All the air 
which enters the jar D must come first through jar A, 
which is filled with a solution of caustic potash that has 



20 



FOOD MATERIALS IN THE AIR CHAP. V. 



the power of absorbing the carbonic acid gas, and then 
through jar B with lime-water. You can draw plenty 
of air through jar D for the use of the plant by sucking 
at the indiarubber tube G, which must be carefully shut 
with a clamp when you stop the current. The bell- jar 
D will now be rilled with air which is quite free from 
carbonic acid gas, and the small quantity which is 




Fig. 12. Apparatus used to keep a plant without any carbonic acid 
gas. A, jar of caustic potash, B, jar of lime water, which absorb the 
carbonic acid gas, through which all the air entering jar D must pass ; 
C, basin of lime water to absorb any of the gas given out by the plant 
growing in D ; G, indiarubber tube which can be closed or attached to 
a siphon to draw air through D. 

breathed out by the plant itself will be absorbed by the 
lime-water in dish C. Place the whole in a light or 
sunny position, and change the air every day or two in 
the way you filled it, that is by drawing at G so that the 
fresh air comes in through A and B, and is free from 
carbonic acid gas. 

If you keep the plant growing under these conditions 
for some time you will find, in comparison with another 
quite similar plant growing in the open near it, that its 
growth is very slow. The leaves it forms are smaller, 



CHAP. V. 



FOOD MATERIALS IN THE AIR 



21 



and finally its growth almost ceases. Further, if you 
test the leaves of the plant growing out in the air for 
starch (see pp. 24 and 25), you will find that they contain 
plenty, but that the leaves on the plant in the bell-jar 
are empty of starch. Now all healthily growing green 
leaves contain starch, so that this is a good proof that 
something is seriously wrong with the plant, which has 
been deprived of the supply of carbon in the air. This 
shows us that plants use the carbonic acid gas in the air 
for their growth. 

Carbonic acid gas is composed of a union of carbon 
and oxygen gas. If, then, the carbon is used by the 
plant, what happens to the oxygen ? 

You must have noticed bubbles rising from the " pond 
scum " and water-plants when they are in the sunlight, 
the little bubbles sometimes coming up in a quick, 
regular succession from the leaves and 
stems. Let us collect this gas and 
test it to find out what it is. This is 
more easily done if the plants are 
living in glass jars, where you can 
see them and get at them readily. A 
very good plant to use is the common 
Canadian water-plant (Elodea), which 
you can buy in aquarium shops if you 
cannot get it from the ponds for your- 
self. Place a handful of this plant in 
a tall, glass jar filled with fresh water, 
and cover it with a glass funnel, 
so as to collect the bubbles as they 
rise. See that the funnel is well 
under the water and support over it 
a test tube full of water, as in fig. 13. 
Place the jar in as bright sunlight as 
possible, when you should see the 
bubbles beginning to come off quite 
quickly. As the bubbles rise in the tube A, the water 
is forced out till the whole vessel is filled with the gas. 




Fig. 13. Jar of Elodea 
in water, giving off bub- 
bles of oxygen gas in 
the sunlight. 



22 FOOD MATERIALS IN THE AIR CHAP. V. 

Then place your thumb over the mouth of the tube of 
gas, and remove it quickly from the water. Test it by 
plunging into it a splinter of wood which has been 
burning, but just blown out, so that it is still glowing. 
If you plunge it quickly enough into the tube, it should 
catch fire and burn brilliantly. Now this is the test 
for oxygen gas, so that we have proved that the tube 
was full of oxygen. This oxygen is the part of the 
carbonic acid gas which is given off by the plant as it 
uses the carbon and frees the oxygen it does not need. 

You will find that the gas bubbles are given off much 
more rapidly when the plant is placed in bright sun- 
shine than when it is shaded, and that when the plant 
is in darkness the bubbles stop altogether. This seems 
to show us that the sunshine must assist the plant to 
split up the carbonic acid gas, and we will find out more 
about this later on (see p. 25). 

We have now found that carbon forms a large part of 
the plant body, that plants cannot grow in air in which 
there is no carbonic acid gas, and that in getting the 
carbon from the carbonic acid gas, they split it up and 
give off the oxygen. So that we see that plants use 
the carbon in the air as well as the salts dissolved 
in the water of the soil as raw materials, with 
which they finally build up their food. We must 
now try to find what food substance it is that they build 
up from these raw materials. 



CHAPTER VI. 
THE FOOD MANUFACTURED BY THE PLANT 

You will remember that much of the food provided in 
the nurse leaves consisted of starch, and that the baby 
plants use this food as they grow. 

In the full grown plant we also find much starch ; in 
fact, nearly all the parts of plants which we eat as food 
contain large quantities of starch, as you can test with 
iodine in potatoes, turnips, radishes, oatmeal, flour, and 
a host of our other vegetable foods. This is also the 
case in many parts of plants which we do not generally 
use as food, for example, in the lily and tulip bulbs, 
underground stems of Solomon's Seal, and the stems and 
leaves of most plants. So that we find that the food 
grains of starch are developed in grown plants, and are 
not only provided for the young ones. 

What is starch made of? Try heating a piece of 
laundry starch on an iron plate or the bars of the grate, 
and you will see that it blackens, and finally, if you put 
a light to it, may burn. If you simply heat it without 
quite burning it, you will find that it chars and goes 
black like a piece of charcoal. The solid element oj 
starch is carbon. Now you may remember that in the 
plant growing under the bell- jar from which we shut out 
all the carbonic acid gas, we found that the leaves did 
not show any starch (see p. 20). The plant had not been 
able to build up starch without the carbon obtained 
from the air. 

The leaves of a plant are spread out in the sunshine 
and air, and it is in the leaves that we get the starch 
first formed. The leaves, in fact, are the food factories 



2 4 



FOOD MANUFACTURED 



CHAP. VI. 



of the plant. You should study the appearance of starch 
in the leaves. As their green colour hides the iodine 
colouration, it is better first to remove it from any leaves 
you are studying in the following manner. So soon 
after picking them as possible, throw them on to some 
very hot or boiling water for a moment. This kills them 
quickly and makes them soft ; then put them in a jar or 
tube of alcohol,* and leave them in it overnight. By 
next day the green colour should be gone, having been 
absorbed out of the tissues by the alcohol, and the leaves 
left yellowish or white. Then put them to soak in water 
till the stiffness caused by the alcohol has gone, when 
you should add the iodine. If you examine ordinary 
leaves in this way you will find that they go violet or 
brownish blue, showing that they contain starch. 

Now do leaves always contain starch? You will 
remember that the oxygen bubbles were given off much 
more quickly from the plants in the sunlight than from 
those in the dark (see p. 21). This shows that the leaves 
in the sunlight split up the carbonic acid gas more 
quickly than the others, which would give them more 
carbon to work on, and therefore it seems that they 
should be able to build up more starch in the light than 

in dull weather or dark- 
ness. You can see if 
this is true by doing a 
simple experiment. 

If you take a leaf 
growing in the sunlight, 
and cover a portion of 
it, leaving the rest ex- 
posed, you will be able 
to see the effect of light 
and darkness on the starch-building powers of this par- 
ticular leaf. To do this use two flat pieces of cork or 




Fig. 14. Leaf partly covered with cork 
sneets, A, and placed ii 



(compare Fig. 15). 



in sunny position 



* Ordinary methylated spirit is rather impure alcohol, which will 
do if you cannot get any better. 




CHAP. VI. FOOD MANUFACTURED 25 

thick cardboard, covered with silver paper or tin foil 
about i in. to i J in. big, and of the same size and shape. 
Place a part of a healthy leaf between them and bind 
them tightly together, as in fig. 14. If the weight of the 
cork makes the leaf bend down out of the full sunlight, 
then support it so that it lies in a position where it is 
well lighted. Leave it untouched for three days, and 
then in the middle of a bright day cut the leaf from the 
tree, remove the cork when you get into the house, and 
immediately treat it as described above for the iodine 
test. You will find that the part of the leaf which was 

exposed shows a good 
violet colour, proving 
that starch is present 
there, while the part 
which was covered is 
only yellowish, showing 

Fig. 15. Same leaf as in Fig. 14 treated that Starch has not been 
with iodine. It shows that the covered part , t , . . , . 

had formed no starch. developed in thlS por- 

tion (see fig. 15). This 

proves that the covered part of the leaf could not build 
starch, so that exposure to the light and air seems to be 
necessary, as we expected. This further suggests that 
it is only in the daytime that the plant can build starch. 
You can see that this is actually the case by testing 
leaves from the same tree at different times of the day 
and comparing the starch in them. For example, test a 
leaf from a certain plant in the early afternoon, when it 
has been exposed all day to good sunlight, and compare 
it with one which is gathered just before sunrise, if you 
can get up so soon (this is, of course, easier in the spring 
or autumn, when the sun does not rise so early as in 
midsummer). You will find that the leaves picked in 
the early afternoon are packed with starch, while those 
picked before the day begins show very little or none. 

What then becomes of the starch during the night ? 

You will remember that we found much starch in 
potatoes, which you know grow right underground, and 



26 FOOD MANUFACTURED CHAP. VI. 

therefore, according to the experiments we have just 
done, should not contain starch. But it is found that 
the starch is made in the leaves through the day, and is 
slowly carried down the stems in solution, and then 
stored (not made} in the underground parts, such as 
bulbs, potatoes, thick roots, and many others. It is like 
the shopkeeper, who collects some money each day and 
sends it every evening to the bank to be stored for him. 
The leaves of the plant are then fresh next day to 
begin the work of building up more starch. 

One of the great contrasts between the leaves in the 
air, and the parts of the plant underground, is that the 
leaves are bright green in colour, and the underground 
parts are yellowish or brown. It has been found that 
the green colour in leaves is very important in the build- 
ing up of the starch. You can see this in the case of 
leaves which have parts quite colourless, as in those 
which are variegated or striped. 
Take the leaves of such a plant, 
which have been exposed to a good 
light, and test them in the usual way 
for starch. You will find that the 
pale stripes of the leaf show no 
colour with iodine, because they 
are empty of starch, owing to the 
fact that the green colour was not 
Fig. 16. striped leaves; there to build it up. The value of 
the white stripes show no the green colour is that it absorbs 

starch when stained with ., f ., 1-11. j 

iodine. the energy of the sunlight, and 

uses it to get the carbon from the 
carbonic acid gas, and then to build the carbon into 
starch. 

Now you will remember in doing the experiments on 
the food solutions (see p. 17), that one of the plants lost 
its green colour, turned yellowish, and finally died. 
That was the plant which had no iron in its food solu- 
tion. We have found, therefore, that without iron a 
plant cannot build up its green colour, and without its 




CHAP. VI. FOOD MANUFACTURED 27 

green colour it cannot use the store of carbon in the air 
to build up its food. This is only one example of the 
importance of mineral salts to the plant. Salts con- 
taining nitrogen are equally vital, while a number of 
mineral compounds are necessary for healthy growth. 
So that we see that the minerals absorbed in solution 
by the roots, as well as the carbonic acid gas absorbed 
from the air by the leaves, and the energy of light absorbed 
by the green colour are all equally necessary to the life of 
the plant, as all help in the building up of its food. 

We have now seen that plants require food just as 
much as animals do ; but that they use different and 
simpler elements from which they build it up for them- 
selves, unlike the animals, which require their starchy 
foods to be ready built up for them. The foods which 
plants make they use in growing, and the other activities 
of their lives, just as animals do. 



CHAPTER VII. 



THE CIRCULATION OF WATER 

As we have already found out, water is one of the things 
which are necessary for the well-being of plants. Seed- 
lings can begin to sprout only when they are well sup- 
plied with it, and in the growing plant it is the water in 
the cells which keeps it firm and fresh. Directly the 
plant is deprived of some of its water it becomes limp 
and flabby, and " withers." We noticed in Chapter IV. 
that the rootlets absorb the water (with its salts contained 
in solution) from the soil, and from them it travels all 
over the plant. The salts dissolved in water, however, 
are in very weak solution, and to provide the plant with 

sufficient of them for its 
growth it is necessary that 
a continuous stream of 
water should enter the 
plant. Howis this stream 
kept up ? 

The leaves play a very 
important part in the 
water circulation, their 
thin expanded surfaces 
giving a large area from 
which the evaporation of 
water can take place. The 
water which comes off 
from them is not gener- 
ally visible to us, because 
it comes off as vapour. However, you can easily make 
experiments which will show you that it actually does 
come off from the leaves. 




Fig. 17. Experiment to show that 
leaves give off water. Notice the drops 
collecting in the tube, which is closed with 
cotton-wool. 



CHAP. VII. THE CIRCULATION OF WATER 29 

Take a large test tube or a small glass flask, and place 
it over a good-sized fresh green leaf, which you leave 
attached to a healthy plant or a branch in water. Round 
the leaf -stalk wrap cotton wool till it fits like a cork in 
the neck of the flask, so that it shuts the leaf into the 
vessel, leaving no communication with the outer air, and 
at the same time does not injure it in any way (see fig. 
17). Very soon, even after an hour or two, you will 
find a misty appearance inside the glass, and this will 
settle gradually in the form of drops of water which 
collect together and run down the sides of the flask. 
You do not see all this water coming off from the leaf 
under ordinary conditions because it goes into the air 
as invisible vapour, but when it is given off continually 
into a closed space the air soon gets saturated with all 
it can hold, and the rest must form liquid drops which 
we can see. If you keep a record of the time of your 
experiment, and also measure the amount of water 
collected in the flask, and then measure the size of the 
leaf, it only needs a little simple arithmetic to give you 
a rough idea of the quantities of water which must be 
given off every day by a single leaf. From that you 
can imagine the amount passing away from a whole 
plant or a great tree ; and I think you will be surprised 
to find how much it is. 

Another simple experiment shows us that the leaves 
play an important part in giving off water. Take 
three flasks with long, thin necks, and of as nearly equal 
sizes as possible. In one place a branch to which a 
number of fresh, green leaves are attached, in another 
a branch of the same size with only small buds (cut off 
the leaves if necessary), and leave the third as a check 
to show how much water has simply evaporated away. 
Fill all the flasks up to the same level with water, and 
mark this in all three when you start. Leave them for 
a day or two and then mark the level of the water, some 
of which will now have evaporated (see fig. 18). This 
will show clearly that more water has gone from the 



THE CIRCULATION OF WATER CHAP. VII. 



one with the branch than from the empty flask, and 
that a great deal more water has gone from the one in 

which was the 
branch with big 
leaves attached. 
You can see 
roughly the rate 
at which the 
water goes off 
from the leaves 
by completely 
filling with water 
an apparatus like 
that in fig. 19. As 
the leafy branch 
(which is firmly 
fastened in the 
cork with no air 
leakage) uses up 
the water, it must 
be drawn along 
the narrow tube, 
which is gradu- 
ated so as to show 
the quantity lost. 

From these experiments we find that even although 
we do not actually see it coming off, yet the leaves of the 




Fig. 18. Experiment to show that leaves give off 
water. The flasks were all filled to the same level I., 
and left for the same time. The one with the leaves 
in it loses far more than the others. 




Fig. 19. Experiment to measure the amount of water given off by leaves 
m a given time. At first the tube is full of water, which is drawn back to 
points i, 2, etc.. as the leaves use it. 



CHAP. VII. THE CIRCULATION OF WATER 



plant give off a great deal of water in the form of vapour. 
By this process large quantities of water are drawn 
through the plant, and the salts in weak solution in it 
are kept and used by the plant as they are needed for 
building up its structure. 

Now you may think that the loss is simply the result 
of evaporation from the leaves, because the surface of 
the leaves is great, and they would therefore naturally 
lose a considerable amount of water by evaporation. 
But this view is only partly correct, because the giving 
off of water by leaves or "transpiration," as itds called, 
is regulated by a number of little pores in the skin of 
the leaf, which can open and close. You can see the 
importance of these pores as water regulators in plants 
which have them only on one side of the leaf, because 
practically all the water escapes from the side on which 
they are situated. 

To see this, take three leaves of the indiarubber tree, 
which is grown so often in rooms. Choose three which 
are as nearly as possible just alike in size and shape. Of 

one of them care- 
fully cover the whole 
of the lower side, and 
the cut-end of the 
stalk, with vaseline 
or coco butter; do 
the same to the upper 
side and the cut-stalk 
of the second leaf, 
and leave the third 
untouched. Fasten 
all three separately 
on to a string so that 
they all hang with 

both sides exposed to the air, and leave them for some 
days. The leaf which was not greased will shrivel up ; 
as it gives up its water and can get no more, it " withers " 
and dies completely. The leaf which was greased on 





Fig. 20. Leaf A greased on the lower side, leaf 
B on the upper side, and C not at all. B withers 
as fast as C. 



32 THE CIRCULATION OF WATER CHAP. VII. 

upper side also withers at about the same rate as the 
ungreased one, but the one which was greased on the 
lower side remains fresh and green (see fig. 20). This is 
because all the pores are on the lower sides of these 
leaves, and in the one greased on the lower side the 
vaseline had completely closed them, and so prevented 
the water from passing away through them. The upper 
surface is well protected against ordinary evaporation by 
a thick skin which does not allow the water to pass 
through it. The leaf greased on the upper side had all 
its pores left open, and so in this way was withered as 
quickly as one not greased at all. Not all leaves have 
their pores only on one side, but in nearly all plants the 
pores can open and shut. These facts show that tran- 
spiration is more than mere evaporation ; it is a " life 
process," that is, a physical process which is regulated 
by the structure of the living plant. 

Transpiration is very important for plants, for it helps 
to keep the continual stream of water going through 
them, which brings with it the necessary food salts. 
Some plants cannot afford to let much water pass away, 
for they find it very hard indeed to get enough to keep 
them fresh ; such plants as live in deserts or on bare, 
sandy places, for example, protect themselves from 
much transpiration by various devices and special 
arrangements, which we will study in Chapter XVIII. 

We have already observed the fact that water enters 
the plant at its roots, and have just seen that it passes 
off as water-vapour from its leaves. Let us now con- 
sider for a moment the manner of its entrance. How 
can water enter the roots of plants ? 

Let us first look at a somewhat similar case in non- 
living things which will, perhaps, help us to understand 
the process in living plants. 

Take a small " thistle-funnel" and tie tightly over the 
wide opening a piece of bladder ; then pour some very 
strong solution of sugar into the funnel and place it in 
a glass of pure water. Mark the level of the sugar with 



CHAP. VII. THE CIRCULATION OF WATER 



33 



L.S 



a label (see fig. 21, S). Leave this for a short time, and 
you will find that the water has entered the funnel 

tube and run up it for quite a 
long way. 

You should take another similar 
tube and do everything in the 
same way, except that you leave 
out the sugar solution. Then 
you will find that the water re- 
mains inside the funnel at just 
the same level as in the outer 
jar. This is the usual behaviour 
of water, and in the first case, 
where the water rose inside the 
funnel, the 
rise was due 
to the influ- 
ence of the 
sugar, which 
hasthepower 
of drawing in 
water. Now 
we can com- 
pare the skin 
of the root 
hairs (set fig. 

9) to the bladder membrane cover- 
ing the funnel, and it has been found 
that inside the cells are substances 
which have the same power of at- 
tracting water as we found was 
possessed by the sugar. So that 
the entrance of water into the roots 
depends chiefly on the attraction of 
the substances within its cells. 

That a large amount of water 

enters the root in this way you can see if you cut off 
a quickly growing plant (a vine is very good if you can 





Fig. 21. "Thistle funnel" 
covered with bladder B, filled 
with sugar solution up to level 
S, and placed in a jar of water. 
After a time the water is seen 
to have risen to W. 




Fig. 22, Plant P, which 
has been cut off near the 
root, is attached by the 
indiarubber tube I to a 
tall glass pipe, which is 
supported by stand S. 
On the glass are marked 
the levels reached by the 
water rising from the 
root. 



(C260) 



34 THE CIRCULATION OF WATER CHAP. VII. 

get it) just near its base, and attach to the cut-end a 
long glass tube in place of the shoot you have cut away. 
You must fasten this tube by a very well-fitting india- 
rubber tube, which you bind tightly so that it will allow 
no leakage, and support the glass. Pour a few drops of 
water down the tube to keep the cut-end of the plant 
from drying up at the beginning of the experiment. 
Then mark the level reached by the water, and do this 
every day as it rises in the tube. You should find that 
for some time it steadily rises day by day (see fig. 22). 

We see in this way that the roots take in a large and 
continual supply of water, and this must get pressed up 
the stem even without the influence of the transpiring 
leaves. This is called the " root pressure," and is a very 
important factor in supplying the plant with water. In 
a plant which is growing under usual conditions, both 
the transpiration of the leaves and the root pressure are 
at work, and are both necessary to keep a good stream 
of water passing through the plant. This stream of 
water provides it with its mineral food materials, and 
also keeps it stiff and fresh, and is, as we have seen, 
absolutely necessary for the growth of the plant. 



CHAPTER VIII. 



LIGHT AND ITS INFLUENCES 

WHEN we were experimenting on the building of starchy 
food in leaves (Chapter VI.) we saw how very important 
and even essential light is for the activity of the plant, 
and it is therefore natural to expect that light should 
influence its growth very considerably. 

You may see the effect of light which comes only from 
one side on plants grown in the windows of rooms. If 
they are left in one position they grow in a one-sided 
manner with only the bare stalks toward the darker side 
of the room and all their leaves turned towards the 
window through which the light comes. If you want 
them to look pretty towards the room side also, they 
must be turned round frequently, so that the leaves 
are drawn in many directions instead of one only. 
The usual effect of light is to make the leaves grow 
towards it. You may 
see this still more 
clearly by placing a 
pot of seedlings in a 
blackened box with 
a small hole on one 
side. Very soon they 
will bend over to- 
wards the light enter- 
ing by it (see fig. 23). 

Leaves can absorb 
most light when their, 
upper surfaces are at right angles to it, and you will 
find some leaf-stems will bend right round in order to 




Fig. 23. Grass seedlings growing in an 
earthenware dish enclosed in a strong box 
blackened inside so that the light only enters 
at a. (Note how the seedlings bend towards it.) 



35 



LIGHT AND ITS INFLUENCES CHAP. VIII. 





allow their leaves to get into this position. For example, 

if you take a pot of nasturtiums growing in the usual 

way, and support the pot on a stand, 

and cover it over with a bell jar which 

has been blackened, or with a black 

box, so that all the light reaches the 

plant from below, you will find that 

in a day or two the leaves will have 

turned completely round on their 

stalks and are now facing the light, so 

that they are upside down in their 

relation to the position of the whole 

plant (see fig. 24). 

In a small plant, or one with only 

a few big leaves, this desire for the 

light is easily arranged for, as there 

is room 
for each 
of them. 
But if 
all the 
leaves of 
a great 

tree were turned in the 
same direction, you will 
see that many of the under 
ones must be shaded by 
the others. This is not so 
bad as one might expect, 
however, owing to the 
wonderful way in which 
the leaves arrange them- 
selves so as to use every 
bit of space they can, and 
yet to overlap and screen 
each other as little as 

possible. Particularly in plants which grow flat on the 

ground or against walls, and which therefore get all 



Fig. 24. Nasturtium 
covered over, so that 
the light only enters 
from below. The leaf 
surfaces bend over to 
face it. 



Fig. 25. Spray of Maple showing 
stalks of leaves of the same pair of 
very different lengths, so as to place 
the leaves well as regards light. 



CHAP. VIII. LIGHT AND ITS INFLUENCES 



37 



their light from one side, this is very well shown. In 
plants with the leaves in opposite pairs you will often 
find one leaf of the pair big, and the other one small, or 
that the leaf-stalks are of different lengths, and if you 
examine this pair in relation to the rest of the branch, 
you will see how it is developed in this way so as to use 
every bit of space it can and get as much light as pos- 
sible without overlapping its neighbours (see fig. 25). 
Although it is true in one way that each leaf works as a 
separate individual, yet each separate 
leaf is only a small part of the plant, 
and they all work together for the 
good of the whole. Branches which 
have their leaves arranged in this way 
so that they seem to fit into a pattern, 
form what is called " Leaf Mosaic." 
You may see this kind of arrange- 
ment among the leaves of very many 
plants (see figs. 25 and 26). 

//, as we have already seen, light is 
so very important for the plant, what 
is the result of growing it in the dark? 
As you know, it will not be able to 
build itself food, and so would finally 
starve and die. If, however, we 
choose a plant which has already 
much food stored up and can there- 
fore grow for a time without making 
a new supply, then we can study the effect of darkness 
on its growth. 

Take some beans which are just beginning to sprout, 
plant them in a pot, and place the pot in some quite 
dark place such as a cellar or a dark room, or cover 
them with a well-made blackened box which shuts out 
all the light. Also take a potato which is just beginning 
to sprout at its " eyes," and keep it in the dark. Both 
these plants have food in reserve ; the beans have much 
in their nurse-leaves, and the potato is packed with 




Fig. 26. Leaves of 
Ivy growing out from 
the stem so as not to 
overlap each other. 



LIGHT AND ITS INFLUENCES CHAP. VIII. 



starch, as you saw before. At the same time grow a 
potful of beans and a potato plant in the light, so that 
you can compare the growth of the plants under the 
two different conditions of light and darkness. 

You will find that those grown in the dark are very 
straggling and of a 
sickly yellowish co- 
lour, and are a great 
contrast to the shorter 
sturdier young green 
plants grown in the 
open air. The stems 
of those grown in the 
dark are long and 
limp, and not able to 
support themselves 
upright, while the 
distance between 
the leaves is very 
great, and the leaves 
themselves are small 
and useless (see fig. 

27). 

Why should 
these plants have 
such a great length 
of stem? It shows 
us, that when the 
plant is already sup- 
plied with food, dark- 
ness does not prevent 

mere growth in length. A grown in the light ' B in the dark - 
In fact it grows faster in length in the dark, which is an 
effort on the part of the plant to grow away from the 
darkness into the light. It economises in material and 
does not form stiff, thick stems and big leaves which 
would be useless until it reaches the light. 

If you now make a small chink in the black box with 




Fig. 27. Seedlings of Bean of the same age, 



CHAP. VIII. LIGHT AND ITS INFLUENCES 39 

which you cover the plants, you will find that they grow 
towards it and through it into the light. Once the tip of 
the stem is outside in the light, it will form the usual 
leaves at the proper intervals from one another. 

The power of rapid growth in length of a plant grow- 
ing in darkness, which economises the material gener- 
ally used for strengthening the plant, and its power of 
growing towards the light, combine to be of practical 
use to a bulb or seed which is planted too deep in the 
earth. You will find that the part underground has 
much the same character as a plant grown in artificial 
darkness, until it reaches the surface. These weak 
underground stems bring the growing part into the 
light, and the plant does not waste material in forming 
large leaves and strong stems underground where they 
would be useless. 

Although light is so important, it does not follow that 
the stronger the light, the better it is for the plant ; just 
as it does not follow that because we like to be warm, 
we like to be as hot as possible. It has been found that 
plants bend away from the light when it is too strong 
for them, as you may see in some plants near one of 
those very brilliant electric lamps. The sun even is 
sometimes too brilliant (English plants, however, do not 
suffer from that very much), and many plants living in 
the tropics and regions of strong sunlight, protect them- 
selves from its direct rays by a number of different 
devices. 



CHAPTER IX. 




GROWTH IN SEEDLINGS 

WHEN once the young plants start growing under 
suitable conditions they steadily get bigger. At first 
sight they appear to grow equally all over, stretching out 

in each direction as 
indiarubber does 
when it is pulled. 
Let us try to find 
out whether this is 
actually the case 

Take a well-grown 
straight seedling and 
measure off along its 
stem and along its 
root, beginning from 
the tip, distances 
i or 2 mm. apart, 
marking them with 
a fine brush and 
waterproof ink. 
Take care not to in- 
jure the plant, and 
also not to make the 
marks blurred or too 
big. Draw the plant 
showing the marks 
on it as accurately as 
you can, and make 
the drawing exactly life-size. Grow it in damp, but 
very loose sawdust, so as not to rub off the marks, and 



Fig. 28. A Bean seedling : A, with divisions 
marked on root and stem; B, after further 
growth, showing where most of the stretching 
has taken place. 



CHAP. IX. 



GROWTH IN SEEDLINGS 



after one or two days take it out and compare it with 
your original drawing. 

You will find that the whole plant is bigger than when 
you first drew it. Look carefully at the marks on root 
and stem, and you will find that they are not all the 
same distance apart, as they should be if the plant had 
grown equally all over. The marks which are widest 
apart are those just behind the tip of the root and below 
the top of the stem, thus showing that there has been 
much more growth in these two regions than in the rest 
of the stem or root (see fig. 28). If you repeat this often 
with many plants you will find that these are the actively 
growing parts of the stems and roots ; the individual 
leaves, of course, are also growing. Thus we see that 
growth is not a simple stretching of the whole, but that 

'there are two definite 
regions where it is 
specially active. That 
of the stem and first 
root carry on the 
growth in opposite 
directions, as we no- 
ticed before (see p. 
n), the normal stem 
growing up into the 
air and the root down 
into the soil. 

You can see how 
very determined the 
directions of growth 
are by planting up- 
side down a bean 
which is just begin- 
ning to sprout, so that 
its root points up into 
the air, As it grows 
you will see the root bending over till it points vertically 
downwards, while the stem bends up and grows straight 




Fig. 29. A, Bean seedling 
planted upside down. The root 
has bent right over and is grow- 
ing vertically down. B, later 
stage of the same. The shoot 
has bent up. 




4 2 GROWTH IN SEEDLINGS CHAP. IX. 

into the air (see fig. 29). The same thing happens if you 
plant a seedling on its side, and even if you take quite 
a big seedling, which has grown in the usual way, and 
then place it upside down in moist air, you will see the 
root and shoot bending in order to get into their right 
positions. This very determined growth on the part of 
roots and stems seems to show us that they must have 
some means of " perceiving " and regulating their posi- 
tion. It is not an accident that they always grow in 
these very definite directions. Let us find out what we 
can about this question. 

Take a seedling and mark its root as you marked 
the roots for the experiment on the region of growth 
(see fig. 28), lay this seedling on its side on soft, damp 
sawdust, so that the root can easily bend into it. Next 
day you should find that the end of the root has bent, 
and that the bend is in just about the same region as 
that which showed the most active growth. 

Is this actively growing and bending region therefore 
the part of the root which " realizes " that the whole is 
in a wrong position, and which therefore bends to put 
it right? 

To answer this question quite fully would require a 
great deal of work, but there are three simple experi- 
ments which you can do, and which will tell you the 
most important facts about it. 

(i)* Take a seedling with a fairly long root which has 
been growing straight down, then very quickly and with 
a sharp knife or razor, cut off the last 2 mm. of the tip 
of the root. Lay the seedling on its side on damp saw- 
dust and examine it next day. It will not have bent, 
even though it has grown in length (see fig. 30, A). 

(2) Take another like it and leave it lying on its side 
for an hour, and then cut off the tip in the same way as 

* It is better to have half a dozen examples for each experiment, 
for the seedlings do not always act quite quickly and correctly, and 
from half a dozen you can see the average result. 



CHAP. IX. 



GROWTH IN SEEDLINGS 



43 



in number one, placing it on its side once more. Next 
day you will find that it has bent in the same way as one 
which had not been cut (see fig. 30, B). 

(3) Take a third, as like the other two as possible, and 
lay it on its side all night ; do no^ cut it till next day, 
when it has definitely begun to bend (see fig. 30, C), 
then quickly cut off the tip, and place it in the upright 
position (C '). You will find that it continues to grow in the 
bent form, the root tip going on to one 
side. It does not seem to know that 
it is growing along instead of down. 
If you keep it in this position for a few 





Fig. 30. Experiments on the bending of the 
root tips in Beans. (See description in text.) 



days it will then get a new tip and begin to grow down- 
wards in the usual way (see fig. 30, D). 

Think over the results of these three experiments, and 
you will see that it is only when the tip of the root is not 
cut off that the plant seems to " realize " that it is not in 
the right position. When the tip is removed it does not 
bend down even when the whole plant is lying horizon- 
tally, and in the other case (fig. 30, C 1 , D) it will keep on 
bending even, after it has been put in its right position. 

We noticed that it is not the very tip itself which 
bends, so that we see that the very tip is the part which 
"feels" what is happening, while the part iust behind it 
grows and bends according to the need of the plant. 



44 GROWTH IN SEEDLINGS CHAP. IX. 

This is a somewhat similar case to what happens 
when you realize with your brain that you are in danger 
on the road, and your feet hurry you across. 

When we come to consider why the root should grow 
downwards in this persistent way, we find that there is 
an outside influence at work on the plant. You know 
when a stone is left without any support that it always 
falls to the ground, and we say that it is attracted toward 
the centre of the earth by the force of gravitation. It 
has been proved that the strong tendency of roots to 
grow down into the soil is largely the result of the same 
attraction, while the stem is not attracted by it but 
driven away, and therefore grows away from the centre 
of the earth. To prove this, however, requires more 
complicated apparatus than you are likely to be able to 
use at present. 

From the experiments which we have done already we 
see that plants, as well as animals, are affected by their 
circumstances, and can in some measure realize them, 
and move to alter themselves in accordance with them. 
Later on we shall find that plants have a similar power 
in relation to light, supply of water, and other things. 
Have we not already observed in plants nearly all the 
signs of life we set out to look for ? (see p. 4). 

There is one very important point about the growth 
of plants which is strikingly different from the growth 
of animals. A young kitten has four legs, a head, and a 
tail, and as it grows to be a cat these only alter a little 
in shape and get larger and stronger ; the number of its 
legs remains the same. A baby plant, on the other hand, 
has its little root and shoot with a few tiny leaves, but as it 
gets older these increase very much in number, till it may 
have many branches and thousands of leaves. In fact, the 
number of its parts is much more indefinite than those 
of an animal ; its body is built on quite a different plan. 
Yet both plants and animals show the same important 
thing in their growth, that is the increase of their living 
body, which they build up out of their non-living food. 



CHAPTER X. 



MOVEMENT 

WHILE we have been examining plants to find out 
some of the facts about their other life properties, we 
have at the same time seen many cases of movement 
in their different parts. 

For example, we found (Chapter IX.) how the tips 
of roots move round to get back their vertical position 
if they are placed horizontally, and how the shoots of 
young plants bend over towards the light when they are 
grown in a dark box where it can enter only from one 
side (Chapter VIII.). Then, too, as the root tip grows 
into the soil or between the crevices of rocks it bends 
round the stones or other things in its way, and it is 
also attracted towards water, thus showing a continual, 

slow movement in its growth. 
The shoot shows a parallel 
kind of movement in follow- 
ing the light and placing 
itself as advantageously as 
possible with regard to it. 

You may see a still faster 
movement if you carefully 
examine a twining tendril. 
Notice how the young ten- 
drils of a sweet-pea are at 

been touched- B beginning to curl fi rs t almost straight, growing 
fifteen minutes after being rubbed . , 

with a twig. out into the air (see fig. 31). 

Now choose such a one for 

the experiment, and another like it which you do not 
touch, but keep to compare with the one on which you 
have experimented. 

Gently rub one side of the tendril with a small rough 







4 6 



MOVEMENT 



CHAP. X, 




Fig. 32. Leaves of Wood-sorrel; A in the day 
position, B " asleep " at night. 



twig, and then leave it alone. You will see that in 
about five or ten minutes it has begun to curve, and in 
a quarter of an hour may have bent round completely. 

Such movement 
is more rapid 
than that in the 
ordinary growth, 
and this power 
of bending so 
quickly is one 
of the special 
characters of 
tendrils, and one 
that is very im- 
portant in help- 
ing them to do their work for the plant and to seize on 
any support within reach as quickly as possible. 

Then there are other movements, one of which you 
must have often observed in the " sleep " of plants. 
Many flowers and leaves close up and bend down at 
night, taking up their usual position again next day. 
This is not the same thing as the opening of buds, for 
it may occur again 
and again in the 
fully grown parts 
of plants. For ex- 
ample, you may 
mark certain leaves 
of wood - sorrel or 
common clover, 
and watch them 
close up at night 
and re-open in the 
morning many 
times. These 
movements are not very fast, and you cannot see the 
plant moving as you can see a kitten waving its tail, 
but the difference is only one of degree. 




Fig- 33- 
position. 



Leaf of Sensitive Plant in its usual 



CHAP. X. 



MOVEMENT 



47 



There are plants, however, which move so quickly 
that you can see them close up their leaves at once at 

the slightest touch. 
This is the case in 
the Sensitive Plant 
(fig. 33), and if you 
only tap one of its 
tiny leaflets 
with a straw, 
that pair of 
leaflets will 
immediate- 
ly fold up, 

Fig. 34. Leaf of Sensitive Plant, leaflets at a 
beginning to close after being gently touched. 





Fig. 35. Leaf of Sensitive Plant quite 

leaf ' stalk faUen ' ^ being 



then the next pair, and 
the next, till the whole 
leaf has closed, when 
it drops quickly down 
(see fig. 35), this move- 
ment only taking a mo- 
ment. If the shock is 

great, all the leaves 

on the plant will close t c s c e h d e ' d and 

up instantly, and they 

move so quickly that you can hardly see them doing it. 

Some foreign plants swing their leaflets round slowly 
like the arms of a windmill, but we have not yet found out 
why they do this. Also in many flowers we find move- 
ment, and in flowers it is generally in relation to the 
insects which visit them. For example, some orchids 
shut up their big front petal with a sudden snap when 
an insect alights on it and shoot the astonished fly 
towards the middle of the flower. 

Parts such as these, which have more power of move- 
ment than the rest of the plant, are called sensitive parts, 
but though in them we see it more clearly than in most 



48 MOVEMENT CHAP. X. 

plants, they only illustrate what is common to all, and 
that is some power of movement. 

The movements which you have seen so far in plants 
are different from those of most animals in one way, and 
that is in the fact that the whole plant remains rooted in 
one place, and only parts of it can move as the circum- 
stances require, while, though an animal moves its parts 
separately, the result of some of those movements is to 
carry its whole body about. This may appear to you a 
great difference between plants and animals, but it is not 
quite so great as it seems ; nor must we forget that there 
are some simple slimy-looking plants which slowly crawl 
along the ground, as well as many minute, green plants, 
which you could only see with a microscope, which 
move their whole bodies and swim about just in the 
way that tiny animals swim. 



SUMMARY OF PART I. 

WE have now done a number of experiments with 
plants, and found out many facts about their way of life, 
and I think you will agree that we have collected enough 
evidence to prove the statement made at the beginning 
of Chapter II. that on the whole plants show the same 
" signs of life " as do animals. 

We have seen that like animals they breathe in a part 
of the air, and that they breathe out with the air the 
added carbonic acid gas, which is the characteristic 
" waste product " of the out-breathing of animals. 

They practically " eat " when they take in substances 
as food into their bodies, even though they have no 
gaping mouths which can open and close. We noticed, 
too, the interesting parallel between young plants and 
young animals, where both (the plants in the food in the 
seed, the animals in their mothers' milk) are supplied 
with ready-made food at first, and as they get older 
have to find what food they require for themselves. 
As regards their feeding, the plants do more work than 
the animals, for they manufacture the starchy food for 
themselves out of simpler elements, while the animals 
require their starch to be ready made. 

Then the fact that plants grow, increasing in size and 
forming new structures, has been known to you ever 
since you were a baby yourself. Although we noticed 
here an important difference between the kind of 
growth in plants and animals, yet the growth itself is 
alike in the two cases, for both plants and animals build 
up their living bodies out of simpler substances which 
they take in as food and change till the not-living food 
becomes part of themselves and is living. 

(C260) 49 E 



50 SUMMARY OF PART I. 

Movement is not nearly so great in plants as it is in 
animals, and most plants are firmly fastened in the 
ground. Yet there are some plants in which we can 
see very rapid movements of some of the parts, while 
many simple little plants living in water can swim 
actively about like animals. All plants show some form 
of movement, though it is generally slow. 

As a result, we find that all the signs of life we noted 
in animals, viz. breathing, eating, growing, and moving, 
are to be found in plants, and we must look on them 
as being just as much alive as animals. We can see 
that their mode of life and the work they do are 
distinctly different from those of the animals, but they 
are no less vital, and important for the world as a 
whole. 






PLATE II. 
A WHOLE PLANT, TO SHOW ALL THE PARTS 



FI.OWCR. 




A POPPY 



PART II. 



THE PARTS OF A PLANT'S BODY AND 
THEIR USES 



CHAPTER XL 
ROOTS 

IF you have a garden of your own, or have even 
watched another person gardening, you must have 
found out that it is not always an easy thing to get rid 
of the weeds, and that when one tries to " pull them up 
by the roots," they often resist it very strongly indeed. 
If you have never done this, try to pull up a large grass 
tuft or a hedge mustard, or any fairly big common 
plant, and you will find that often when it does not 
look very strong it may be extremely difficult to get it 
completely out of the soil, and even when it comes out 
you may find that you have not got it quite whole, for 
the finer branches of the root will generally break off. 
Now this shows us one of the uses of its roots to a 
plant ; they keep it firmly in the soil, and prevent the 
wind from blowing it away, and people or animals from 
overturning it too easily. 

To see the form of a complete root it is wise to choose 
a fairly small plant, let us say a daisy, wallflower, candy- 
tuft, or young holly ; then loosen the earth all round it 
and pull it very gently from the soil. Shake off the 
mud and then wash it clean and spread it out on a 
sheet of white paper so that you can examine it pro- 
perly. Notice that there is a central chief root, with 
many side branches which have again finer and finer 
branchlets (see fig. 36). At the tip of the very finest 
you should see a number of delicate hairs, the root 



54 



ROOTS 



CHAP. XI. 



hairs, 
these 



but it is very possible that you will have torn 
off with the soil. To see them best, look at some 

of your seedlings which 
have grown in moist air, 
where they are very well 
developed (see fig. 8). In 
any of these plants you 
will notice that the main 
root seems to be a down- 
ward continuation of the 
main stem, and that the 
side roots come off all 
round it, just as was the 
case in your bean seed- 
lings (see figs. 36 and 7). 
Such a root is called a 
tap root 

Now dig up a small 
grass plant and compare 
its root with these, and 




Fig. 36. Root of a young Holly : J, level 
of soil ; s, stem ; c, chief root with many 
side branches and finely divided rootlets. 

you will see that there is no 
main root, but very many roots 
coming off in a tuft from the 
base of the stem, just as was 
the case in your corn seedlings 
(see fig. 37). The difference be- 
tween these roots and tap roots 
is not of much importance as 
regards the actual work they 




Fig. 37. Grass plant, showing 
the many finely divided roots. 



do but is one of difference in form ; the finer branches 
in both are very similar and have the same work to do. 



CHAP. XI. 



ROOTS 



55 



If you leave the plants you have pulled up lying in 
the air for an hour or two, you will find that they will 
wither, the leaves becoming quite limp and the whole 
plant drooping. Now place them with their roots only 
in water, and you will soon find that they are beginning 
to revive. They will revive fully and live a long time if 
their roots are kept in water. This reminds us of the 
second very important use of its roots to a plant, which 
we have already found out (see Chapter IV.), and shows 
us again that the roots absorb water and keep the whole 
plant supplied with it. Of course you know that cut 
flowers can drink up water with their stems, but that is 
only for a short time, and is not quite natural. The 
special part of the rootlet, which does the actual absorp- 
tion, is the part near the tip which is covered with root 
hairs. You have already seen these root hairs in the 
course of your work (see pp. 13 and 15). 

There are then two chief duties of 
roots, to absorb water from the soil for 
the whole plant L , and to hold it firmly in 
the ground. The fine fibres of the root, 
which are so much divided and run in 
the soil, serve both these purposes, as 
they expose a large area to contact with 
the soil, and so can absorb much from 
it, as well as getting a good hold of it. 

As well as these two chief functions, 
there are many other pieces of work 
which roots may do, and according 
to the special work they take up, so they 
become modified and look different 
from usual roots. 

One thing they often do is to act as 
storehouses of food. For example, ex- 
amine the root of a carrot. The part 
we commonly call the carrot and which 
we eat, you will see is really the main axis of the tap 
root, and has the little side roots attached in the usual 




Fig. 38. Tap root 
of Carrot, swollen 
with stored food, 



ROOTS 



CHAP. XI. 



way. The unusual thickness of the main root is due to 
the large quantities of food which it stores. Just in the 
same way radishes 
and many 
plants have 




Fig. 39- 
with food. 



Dahlia, with storage roots packed 



other 
their 

main roots very 
thick and packed 
with food, while 
dahlias have their 
side roots thicken- 
ed in a similar way 
(see fig. 39). Such 
modified roots, 
which look quite 
different from or- 
dinary ones, are 
called Storage 

roots, and if you examine many of them you will find 
them packed with starch (see p. n for iodine test). 
Although it is general for the roots to hold the plant 
firmly in the ground, in some cases they 
grow out of the stem in the air and help 
to hold it up against a tree or wall, or 
some support, as in the case of ivy. If 
you pull off a branch of ivy which is 
climbing up a tree you will find that all 
along the back of the stem there are 
tufts of short thick rootlets which often 
come away holding a piece of the bark 
of the supporting tree. These roots, 
you will see, do not come out in the 
usual way from the main root or base of 
the stem, but come out all along the 
stem itself (see fig. 40). Such special 
roots are called " Adventitious," and 
they grow from the stem wherever they are needed. 

Adventitious roots may also come out from a wounded 
plant which has had its true roots cut away. For 
example, take a piece of Forget-me-not stem without 




Fig. 40. Adven- 
titious roots grow- 
ing out from the stem 
of Ivy between the 
leaf stalks. 



CHAP. XI. 



ROOTS 



57 




Fig. 41. Tufts of aii 
roots of an Orchid. 



any roots, and slit it at the base, and put it in a glass of 

fresh water. After a week or so you 

should see little white roots growing 

out from the stem into the water, and 

if you let them get strong you may 

then plant the sprig and get a new 

forget-me-not plant from it. In this 

and all ''cuttings" adventitious roots 

growing out from the stem do the 

usual work of roots. There are many 

other kinds of adventitious roots, but 

we must only mention the orchids, 

some of which have long tufts of 

roots which grow out irregularly from 

the stem and hang in the air. These 

are special air-roots, and grow on 

many orchids, but also on some other 

plants which live attached to trees and absorb the water 

out of the air instead of from the soil (see fig. 41). 
There are many other curious roots, particularly in 

plants which grow in 
tropical countries, e.g., 
the stilt roots which come 
out from the base of the 
stems of many palms and 
make tripod-like supports 
(see fig. 42), and others 
which grow from the high 
branches to the ground 
like pillars, and prop up 
Fig. 42. supporting or stilt roots the heavy trunks. How- 

fna Wi ot S utfromthebaseofasmallPalm ever, we do not need to 

go so far to find very many 

different kinds of roots, and if you examine carefully 
those of the plants growing in our woods and lanes, you 
will find what a number of extra pieces of work they can 
do, in addition to their two chief duties of drawing in 
water from the soil, and holding the plant in its position 
in the earth. 




CHAPTER XII. 

STEMS 

EXAMINE the stem of a sunflower ; it is tall and straight 
and grows upright in the air, bearing leaves which stand 
out from it. 

In a young holly, and many other plants, we find 
growing out from the central stem smaller side branches 
which bear the leaves. As we have found already 
(Chapter VI.), the leaves are the active parts of the 
plant and do the food-building, so that the stem is 
chiefly useful as a support, which keeps them in a 
good position as regards the light and air. In general, 
we do not see much of the stem because it is largely 
hidden by the covering of leaves, so that if you want to 
study stems you should go to the woods in the winter 
when there are no leaves on the trees, and you can see 
the form of the branches themselves. 

In big trees, such as the oak and beech, the stems 
are very important, and the chief stem or trunk becomes 
very thick as it gets old. It is made of hard wood which 
is tough and strong, for such high trees have to bear 
great strain from the winds, as well as the weight of all 
the leaves. If you go into the woods when it is very 
windy, and watch the thick wooden boughs swaying, 
boughs which you could not move, you will see how 
much force the wind may sometimes have. The 
branches need all their strength in the summer to 
support the curtain of leaves which catches the wind. 
In a big tree we find the few chief branches thick and 
strong, but there are many hundred smaller ones, some 
of them dividing to quite delicate branchlets which 

58 



CHAP. XII. 



STEMS 



59 




Fig. 43. Much-branched stem of 
the Oak. 



bear the leaves, so that the whole tree body is very 

much complicated (see fig. 43). 

Each kind of tree has a way 
of branching which is charac- 
teristic of its species, so that 
even without leaves or flowers 
a woodman can tell what a 
tree is. This one can learn 
by practice in the woods, but 
to begin with it is rather diffi- 
cult. Without going into de- 
tail, however, we may notice 
great family differences, such 
as exist between a larch or a 
Christmas-tree and an oak. 
In the first two there is 

one straight main trunk, with side 

branches at very regular intervals (see 

fig. 44), and in the oak the main thick 

trunk soon bears several large branches 

nearly equalling the main stem ; these 

divide again and again in a rather 

irregular fashion (see fig. 43). 

In many of the smaller plants the 

stems are not strong enough to stand 

up against the wind, and they simply 

lie along the ground or support them- 
selves by growing among other plants, 

such, for (example, as the common 

Stellaria, where the stem is very deli- 
cate indeed (see fig. 45). Then again, 

if you pull up a large water-lily, you 

will notice how soft and limp the long Fig.44. The Larch, 

leaf -stalks are. They cannot support showing its strong cen- 

themselveS at all in the air, though delicate^ide^ranches 6 

they were upright in the water. This 

is because the stalks get their support from the water 

which allows them to float up, so that the plant does 




50 



STEMS 



CHAP. XII. 







stemof theStellariajpartly 



not build a strong stem. You will find that plants are 

very economical in their use of strengthening material, 

and never waste it 

where it is not want- 

ed. If you remember 

this, and then study 

all the stems you can, 

and note when and 

where they are streng- 

thened, you will find 

what good and econo- 

mical architects 

plants are. 

As well as support- 

ing the leaves, the lying on the ground 
stems have another 
very important duty, something like that of the roots. 
Just as the roots absorb the water from the soil and 
carry it up, passing it on to the stems, so the stems carry 
it on to the place where it is finally used, that is, to the 
leaves. In both stems and roots there are channels or 
" water-pipes " which carry water about, as well as other 
special " pipes " which carry the manufactured food. 

So that the two chief duties of stems are to act as 
supports for the leaves and flowers, and to carry the food 
materials and water between the roots and leaves. 

Just as we found in the case of the roots, there are 
many extra duties which the stems may take over, 
and as a result, we find great variety in the appearance 
of stems. For example, in some plants the stem does 
not grow up into the air at all, but creeps along just below 
the surface of the ground. This you may see if you dig 
up a Solomon's Seal or an iris, when you will find that 
the stem looks very like a thick root running horizontally 
in the ground. That it is really a stem you can tell from 
the fact that the leaves grow out from it, and you can 
see the scars of old ones as well as the present leaves, 
and also some little brown scaly leaves, and a large number 



CHAP. XII. 



STEMS 



61 




Fig. 46. Underground stem of the Solomon's 
Seal, called a Rhizome. It has many scaly leaves, 
s and a shoot A which will come out into the air 
bearing green leaves. B is the scar left by the 
similar shoot of last year, r are the adventititious 
roots which come out all over the stem. 



of adventitious roots. The stem is rather swollen with 
food materials which are stored up in it, and 
it is not coloured green like many of those 
growing in the air. Such a stem, creeping 

under the earth, 
and only sending 
its green leaves 
into the air, has 
a special name, 
and is called a 
Rhizome. Many 
plants have such 
stems, particular- 
ly ferns, as you 
can see very well 
if you dig up a 
bracken. 

Some of the un- 
derground stems 

which store food are still more modified, so that it is very 
hard indeed to tell what they really are. This is the 
case in the potato, which you would naturally think at 
first is a swollen root, like those we saw in the dahlia 
(fig. 39). That it is really 
a stem you can see by ex- 
amining the "eyes" care- 
fully. The eyes (see fig. 
47) are buds with scale 
leaves round them, and at 
the tip of the potato we 
can see several such buds 
together (fig. 47*). The 
whole potato is a very 
much swollen stem which 
is packed with food and 
has all its other parts so 

reduced that it is difficult to recognise them, 
special stems are called Tubers. 




Fig. 47. A Potato : s, the stem attach- 
ing it to the main stem ; , scale-leaf ; 6, 
bud in its axil ; /, tip of the Potato with 
several buds, some of which are sprout- 
ing. 



Such 



STEMS 



CHAP. XII. 




Fig. 48. Cactus plant, showing 
its fleshy stem, which is green, 
and does the food building for 
the plant. The tufts of spines 
and hairs represent the leaves. 



Certain stems take on the work of leaves, and some- 
times they are so much modified for this that the plant 
has no true leaves at all. This is what has happened in 

the case of a cactus. If you 
can get a cactus, examine it 
carefully and you will see that 
the whole plant consists of a 
thick mass of green tissue, 
which apparently is not di- 
vided into stem and leaves. 
But the truth is that the whole 
of the thick mass of tissue is 
the stem, and the little tufts of 
spines and hairs are really re- 
duced leaves. So that in the 
cactus the green stem does all 
the food building work instead 
of the leaves. 

In some plants this is not so 

much marked, even though the stem does some of the 
work for the leaves. In such cases the stem is gener- 
ally green and broad or winged and the leaves small, as 
in our common broom and the whortleberry, where 
the leaves very soon drop off. Quite a number of 
plants have stems which do this, and it is sometimes 
a great advantage to the plant, for the big leaves are 
often very wasteful of water, as you will see in Chapter 
XVIII. 

In other cases we find that the side branches of 
stems may be modified to protect the plant, and so 
take on the form of strong spines or thorns, as in 
our blackthorn, where the sharp pointed spines are 
modified side shoots. 

There are many other pieces of work which stems 
may do ; we must just mention the climbing and twin- 
ing stems, where the stem is delicate and requires to be 
supported, which we are going to examine more care- 
fully in Chapter XIX. 



CHAP. XII. 



STEMS 




Sometimes, instead of con- 
tinuing to grow into the air, 
the stem may bend over 
into the earth again, as often 
happens in big bushes of 
bramble (see fig. 49), and 
then from the tip of the 
stem a number of adventi- 
tious roots (see p. 56) grow 
out and hold it firmly in 
the ground. If, then, this 
branch gets separated from 
the rest of the plant, it 
can build a complete new 
individual. 

In the case of the bramble 
notice how the leaves get 
smaller and smaller towards 
the tip of this branch as it 
bends down to the earth, 
and of course, they do not 
develop at all as true leaves 
under the soil (see fig. 49). 

From these examples, and 
the many others you should 
be able to find for yourselves, 
you see that stems may take 
on other duties beyond 
their two chief ones, but that, 
however much they change 
their form and appearance, 
we can always find out that 
they are really stems by 
g studying them with a little 
care. 



Fig. 49. Leafy branch of Bramble which 
has bent into the earth and given rise to 
a cluster of adventitious roots at the tip ; 
/, level of soil ; P, point where the branch 
was cut from the parent plant. 



CHAPTER XIII. 

LEAVES 

THE late spring and summer are the best times to study 
leaves, for, as you must have noticed, the woods begin 
to lose their green in the autumn, and the leaves have 
fallen in the winter. This tells us that the fresh green- 
ness of the leaves (which you know is so important 
for the plant) does not last very long, and when they are 
no longer green the leaves are useless and drop away. 
As you know, the chief work of leaves is to build 
starchy food, for which they require their green 
colour. 

When you go into the woods or gardens to study the 
leaves, first look at single ones, 
collecting as many kinds as you 
can. Though their shape varies 
very much, you will find that in 
almost all cases they are green, 
expanded, and flat. Let us first 
examine a single simple leaf, like 
that of a cherry. You will see 
that the expanded part (called 
the leaf blade or lamina] narrows 
down to a small stalk, which con- 
nects the blade with the stem 
from which the leaf is growing; 
this stalk is called the leafstalk or 
petiole. Then at the base of it, 
just where it joins on to the stem, 
there are two little leaf-like struc- 
tures which are not true leaves, but which belong to 




Fig. 50. 
Cherry. 



Simple leaf of the 



CHAP. XIII. 



LEAVES 




the leaf and are called stipules; they are attached to the 

base of the petiole, which spreads out to clasp the stem, 

and is called the leaf base (see 

fig. 50). Such a leaf shows 

us all the parts of a simple 

leaf ; but some leaves have no 

stalks, others no stipules, and 

so on. 

Let us compare a rose leaf 

with the simple leaf of a cherry, 

oak, or beech. In the rose you 

will find five or seven small 

leaflets arranged on a single 

main stalk, and each of these 

leaflets separately is very much 

like a single leaf of the beech. 

Such a leaf as this we call 

compound, for it is divided 

up into several parts, each of 

which looks like a whole leaf 

(see fig. 51). 

Leaves are of very many different kinds and shapes, 

and special names have been given to each kind, which 

you can look up in a book if you want to classify them. 

Let us just notice a few of 
the types. The cherry, beech, 
and others which are simple 
with slightly pointed ends, 
we may call by the proper 
term ovate. Then there are 
leaves like those of the nas- 
turtium, where the leaf blade 
is circular and the leaf stalk 
does not come in at the base 
of the leaf, but is attached to 

the middle of it ; such leaves as that are called peltate. 
The broad or rounded leaves, which spread out like 

the palm of a hand, such as the ivy (see fig. 26), are 

(C2GU) Fl 



Fig. 51. Compound leaf of the Rose. 




Fig. 52. Peltate leaves of Nastur- 
tium, showing the stalk attached in 
the middle of the lamina. 



66 



LEAVES 



CHAP. XIII. 




- 53- Needle leaves of Pine grow 
ing in pairs. 



called cordate or lobed, and when compound, as are 

those of the horse chest- 
nut, palmate. 

All the grasses and the 
many plants belonging to 
their family have very long, 
narrow leaves, which we 
call linear, while those of 
the pine trees are sharp and 
pointed, and are called 
needle leaves. 

As we noticed in com- 
paring the leaves of the rose and cherry, some plants 
have very much more complicated 
leaves than others. Now such 
complicated structures do not de- 
velop on a plant all at once, as 
you can see if you examine a very 
young rose seedling. The first 
pair of leaves or cotyledons do not 
remain inside the seed as they do 
in the bean, but grow outside into 
the air and become green ; they are 
quite simple leaves with smooth 
edges. The next leaf which un- 
folds is also simple, but it has a 
deeply toothed edge (see fig. 54), 
while the leaf following that is a 
compound leaf, divided into three 
leaflets. The other leaves gradu- 
ally get five and then seven leaflets 
as the seedling grows up. 

This is just one example of what 
usually happens in the history of 
plants with compound leaves, or 
leaves with any special shape ; 

the young seedling's earlier leaves are much more 
simple than the later ones. You should collect as many 




Fig. 54. Seedling of Rose; 
(c] cotyledons ; (a) next leaf, 
simple, but toothed ; (b) next 
older leaf divided into three 
leaflets. 



CHAP. XIII. 



LEAVES 



67 



seedlings as possible and make drawings of them if you 
can, to show the various stages leaves pass through 
before reaching the full-grown complex form. 

Now let us look again at the actual structure of leaves. 
Hold up those of the rose, or lilac, or lime tree to the 

light, and look at 
the " veins " run- 
ning in them. 
There is a chief 
central vein or 
mid-rib, and from 
it a number of 
side branches 
come off and di- 
vide and branch 
again and again 
till they form a 
fine net-work 
throughout the 
whole of the leaf 
blade (see fig. 55). 
If now you look 
at a grass or lily 
leaf, you will find 
that there are very 
many veins about 
equally import- 
ant, running from 
end to end of the 




Fig- 55- Skeleton of a leaf, showing the fine net- 
work of the small veins. 



leaf and remain- 
ing nearly parallel to each other. This difference 
between parallel veins and net-work (or reticulate] veins 
is quite important, and is one of the characters which 
help to separate two very big families of flowering plants 
(see Chapter XXIII.). 

Now let us see in what way the leaves are arranged on 
the stem. If you pick a branch of dead nettle you will 
see that the leaves are attached by their stalks to the 



68 



LEAVES 



CHAP. XIII. 




stem in pairs, two leaves coming off from the same level 

at opposite sides of the stem (fig. 56) j while fig. 57 shows 

that the leaves 

of honey-suckle 

really do the 

same thing, only 

they grow out 

directly from the 

stem as they have 

no leaf stalk. Now 

look once more 

at the leaves of 

the dead nettle, 

choose one par- 
ticular pair to 

start with, and 

then look how 

the pair above it 

are placed. You 

will see that they 

do not lie directly above the pair you chose, but are 

arranged on the opposite sides of the stem, so that the 

two pairs alternate. If then you look at the pair next 

above them, you will see that 
they are arranged in just the 
same way as the first pair, and 
so alternate with the second. In 
this way every pair of leaves on 
the stem alternates with the pair 
above and below it. Now ex- 
amine a pear or cherry twig, and 
you will see that the leaves are 

n^ n ieaf arran g ed sin gly on the stem. 
Fasten a piece of thread to the 
stalk of one leaf and twist it 

round the base of the next, then on to the next above 
and so on. You will find that the thread makes a spiral 
round the stem, and finally comes to a leaf higher up it, 



Fig. 56. Alternating pairs of leaves of the Dead 

Nettle. 




stalks. 



CHAP. XIII. 



LEAVES 



69 





Fig. 59. Leaves 
arranged in a whorl 
in the Horsetail. 



which lies exactly above the one you started from. 
Very many plants have their leaves arranged like this in 
a spiral on the stem with the youngest at 
the top. There are different kinds of 
spirals for the arrangement of leaves in 
the different plants. You can see this by 
making the spiral of 
thread and counting 
how many leaves you 
pass on your way up 
the stem till you reach 
the leaf which lies just 
immediately above the 
one you start from. 

Sometimes the 
leaves are arranged in 
a circle all round the stem at the same 
level; this is the case in the horse- 
tail (see fig. 59), and such an arrange- 
ment is called 
a whorl, but it 
is not very 
common in 
plants. 

In the goose 
grass the 
leaves look 
very much as 
though they 
were really in 
a whorl (see fig. 
60), but there 

are only two true leaves ; the oth- 
ers are the stipules, which are so 
much like the leaves that it is very 
difficult to tell them apart. 

As we found out already, leaves require light and air, 
and usually arrange themselves so as to get them ; 

(C260) F2 



Fig. 58. Branch of 
Cherry (leaves cut off 
to make it clearer), with 
a string twisted from 
leaf stalk to leaf stalk, 
showing the spiral ar- 
rangement. Note that 
leaf 5 is the first to come 
immediately above the 
one you started from. 




Fig. 60. Leaves of Goose 
grass looking like a whorl. 



LEAVES 



CHAP. XIII. 



hence, in a general way, we may observe that the 
leaves all grow to face the light. If you go under a 
beech tree, for example, and look up, you will find that 
you can see nearly all the big branches on the inside, 
while the leaves form a covering or dome on the outside. 
Special cases of leaves so arranged as to get a good light 
we noticed before (see pp. 36 and 37). 

As well as their own particular work, leaves 
may take on extra and different work, so becoming 
modified to suit their different occupations, and unlike 
true leaves. We already noticed in the cactus (see fig. 48) 

that the leaves become 
like sharp spines which 
protect the fleshy stem, 
and can do none of the 
usual work of leaves, 
because they have lost 
their green colour. 

In some plants leaves, 
or parts of leaves, may 
change into fine tendrils 
whichbecome very sen- 
sitive to touch, and can 
twine round supports 
and cling to them, and 
so help the plant to 
climb. Such tendrils 
we saw (fig. 31) move 
very quickly ; they are 
quite different in their 
structure from ordinary 
leaves. This happens 
in many plants, and you 
may see it very well in 
the sweet pea (see fig. 
61), where only two 

leaflets of the compound leaf remain leaf-like, the others 
having been changed into tendrils. 




Fig. 61. Leaf of Pea, showing leaflets 
modified as tendrils (t] ; expanded leaflets (o). 



CHAP. XIII. LEAVES 71 

When we come to look at Flowers, with all their 
special shapes and brightly coloured parts, we are really 
looking at modified leaves. But they are so very much 
modified that we have come to consider flowers as things 
by themselves, and so we will study them later on. 

Some plants which do not have true flowers, yet have 
leaves of two kinds. For example, the " flowering fern " 
has the usual green leaves and others which form rather 
brownish golden spikes, and which are covered with 
spore* cases. Then again, some leaves are very specially 
modified and are changed from the usual structure in 
order to act as traps for insects (see Chap. XXL). 

Other leaves, instead of being very much developed, or 
specially developed along some line, are simply reduced, 
that is, are very little developed indeed. For example, 
as you saw in the under-ground part of the potato and 
many rhizomes growing horizontally, the leaves never 
become large and green, but remain as simple brown 
scales. Some scale leaves have quite a special work to 
do in the way of protecting the very young green leaves 
while they are in the buds, and we will look at these 
carefully in the next chapter. 

We have now seen that leaves, like all the other parts 
of the plant, can modify themselves in a very great 
number of ways, and may do many extra pieces of work 
above and beyond their chief work of food manufacture. 



* Spores are simple little structures which do much of the work of 
seeds. See the Chapter on Ferns. 



CHAPTER XIV. 



BUDS 

THE proper time to study buds in nature is the spring, 
but then you will have to wait long to see all the different 
stages of their slow unfolding. But they can be made 
to open artificially, and it is really wise to study buds in 
winter, when there are not so many other things to do. 
You can arrange this very well if in the late autumn you 
cut off fairly big branches with buds 
on them (horse chestnut is particu- 
larly good for this) and keep them in 
a warm room. You must, of course, 
keep the cut ends of their stalks in 
water, which you should change every 
three or four days, sometimes cut- 
ting off a piece from the ends of the 
branches so that they have a fresh 
surface exposed to the water. In 
this way they should live for months, 
and may just begin to unfold and 
show fresh young green leaves about 
Christmas time, when the buds on the 
trees out in the cold are still tightly 
packed up. 

Watch the buds as they unfold, and you will find that 
round each bud are several dry brown scales; these 
drop off, and within them are more green, leaf -like 
scales enclosing the true young leaves, which are 
still curled up and very small when they first come 
out. 

If you examine a big bud which has not yet begun to 




Fig. 62. Buds of the 
Horse Chestnut begin- 
ning to unfold. 



CHAP. XIV. 



BUDS 



73 




Fig. 63. Bud of 
the Horse Chestnut, 
showing the over- 
lapping of the scales. 



unfold, and carefully pull off all the parts separately 
with the help of a needle and knife, you will see how 
the outer scales fold over one another like a coat of 
mail, and where they are exposed to 
the outside air they are hard and shiny, 
and in many plants are covered over by 
a sticky waterproof substance like tar- 
paulin. These outer scales keep off 
the rain and snow, and keep the inner 
parts dry and unharmed. Within them 
the scales are softer and often quite 
green, and they, too, wrap round each 
other, so that there is no crack left which 
could allow the cold rains to enter to 
the little leaves within. In many cases 
also the young leaves are wrapped up 
in soft, long hairs which look almost 
like cotton wool. These hairs grow on the leaves 
themselves, and you can see them after they have 
opened out, but as the leaves are then much bigger, 
the hairs are scattered further apart 
and do not show so much. 

If you cut right through the length 
of a bud with a sharp knife, you will 
see how all these scales and young 
leaves are packed together, as in fig. 

6 4 . 

Take another bud and carefully pull 
off all the scales one by one and lay 
them in a row, beginning with those 
right outside ; you will see that they 
get less scale-like and more like real 
leaves as you go in towards the centre 
of the bud (see fig. 65). The outside 
simple brown scales scarcely look like 
leaves at all, but the inner ones are green and soft, and 
in some plants, those right inside have quite a leaf -like 
appearance. 




Fig. 64. Bud cut 
through lengthways, 
showing the bud- 
scales and young 
leaves packed with- 
in them. 



74 BUDS CHAP. XIV. 

This helps us to see that bud scales are really only 




Fig. 65. A series of bud scales from a Horse Chestnut ; (a) 
and \b) are entirely hard and brown ; (c) and (d) are brown at 
the tips and green at the base, where the others cover them ; 
(e) is quite green, soft, and leaf-like. 

modified leaves, which are altered for their special work 
of protection of the young leaves through the winter. 

Of course, you know that the buds are already on the 
trees in the late autumn after the leaves have fallen ; but 
have you seen the buds already there in the summer 
while the leaves are still fresh and green ? If you look 
for buds you will be sure to find them, and at the same 
time you will learn where they grow on the stem. You 
must look right at the base of the leaf stalk, in the 
angle made by the leaf stalk where it joins the main 
stem ; this is called the axil of the leaf, and it is in the 
axil of the leaf that you will find the small green buds 
in summer-time. These buds grow out in the following 
year, so that a new leaf comes in very nearly the same 
place as the old one, or, what is more usual, there 
grows out a new branch which may bear several new 
leaves. Now examine a twig of horse chestnut or 
sycamore from which the leaves have dropped ; notice 
that, where the buds are to be seen on the stem, 
they lie immediately above scars of a definite shape, 
which are the scars left by the fallen leaf stalks, as you 
can see by comparing them in the autumn with leaf 
stalks which are just falling away (see fig. 66, /, b, 
and s). 

On the stem there are other scars, which are different 
from the ordinary leaf scars, and which are like bands 
of fine lines round the stem. What are these ? Now 



CHAP. XIV. 



BUDS 



75 



if the single big leaf stalk leaves its scar so clearly on 
the stem, what kind of scar would a number of thin 
scales lying close together be likely to leave ? Will it 

not be a number of narrow scars 
in a band, just such a scar as we 
have here (fig. 66, a, a 1 , and 
J(/ m a 2 ). If you mark a bud on a 
tree or one of the branches in 
your room and watch it unfold, 
and keep a note of it till the 
autumn, you will find at its base 
where the bud scales were, that 
there is then a scar just like this. 
Whenever you see such a scar 
you will know that it has been 
left by a bud. Now you know 
that, as a rule, trees have buds 
only once a year, so that each 
of the bud scars along the stem 
must represent a past year's bud, 
and if you count these scars 
along the length of the stem it 
will tell you the number of years 
the stem has been growing. For 
example, in fig. 66 the twig shows 
us five years' growth if you count 
the last bud which will grow out 
to form a shoot; 

The buds which come in the 
axils of the leaves along the stem 
may form new leaves, or may 
develop into side shoots with new 
stems and leaves. There is an- 
other bud, generally bigger than 



Fig. 66. Branch of Sycamore, showing leaf 
stalk (/) with bud (6) in its axil. Scars of leaf stalks 
(s) and large terminal bud (/) with scars (a), (a 1 ), 
and (a 2 ) left by the terminal buds of past years. 



7 6 



BUDS 



CHAP. XIV. 



these, which grows at the end of the shoot (/, fig. 66). 
This has just the same structure as the others, but it 
will certainly grow out to form a stem and carry on the 
line of growth of the main shoot, unless it is injured. 

The amount that the shoot grows in one year depends 
on very many things, on the light and warmth it gets, 
on its food and the growth of its neighbours. Hence, 
in the growth of different shoots in the same year, or 
the same shoot in different years, we find very great 
differences. Sometimes a number of bud scars lie very 
close together, showing that for several years it had only 
grown a small amount, while in the years following it 
may have added very much to its length. In some 

plants there are little 
side shoots which ne- 
ver grow much, and 
always remain quite 
short; for example, in 
the larch each tuft of 
leaves grows on a little 
stunted stem which 
represents several 
years' growth, and 
which never reaches 
any length (see fig. 67). 

Not only do we get leaves and stems packed away in 
buds, but the flowers for next year are there also. For 
example, examine several of the big horse chestnut buds 
from the outer branches of the tree, and you will be sure 
to find tiny sprays of young flowers packed away in the 
hearts of some of them. 

There are some quite special buds which we must 
notice, and which at first sight appear very different 
from real buds. They have been given a different name, 
and are called Bulbs. Cut right through a tulip or 
hyacinth bulb lengthways, and compare it with a horse 
chestnut bud to which you have done the same. The 
arrangement of the parts of the two things seems to be 




Fig. 67. Larch, with tufts of leaves growing 
from short side shoots. 



CHAP. XIV. 



BUDS 



77 



very similar. If you examine the bulb in detail, you 
will find that it is protected on the outside by brown, 
hard scales, and that the softer leaves within are folded 
over each other very much like those in the true buds. 
Now the bud of the horse chestnut is attached to the 
parent stem is there nothing corresponding to the stem 
in the tulip bulb ? Look carefully at the base, and you 

will see a little mass of tissue 
which holds the scales to- 
gether (see S, fig. 68) ; this is 
the stem, which is short and 
very much reduced, being 
unlike a usual stem. There 
is also one great difference 
between the scales in the 
bud and the bulb. In the 
bud they are rather thin and 
dry, but in the bulb they are 
thick and white and very 
fleshy, and if you test them 
with iodine, you will find 
that they contain much 
starchv food. They form 




Fig. 68. Bulb cut through, show- 
ing the overlapping scales (5) packed 
with food attached to the shortened 
stem S . B is the bud , which will grow 
out into the air, and (ft) the bud which 
will form a new bulb next year ; (r) 
adventitious roots growing from the 
base of the stem. 



the storehouse of the tulip, 
and this food will be used 

by the plant when it begins to grow. In the axils of 
these thick fleshy leaves you may often find small buds, 
which will get large and fleshy by next year and form 
the new bulbs (see fig. 686). 

Sometimes little bulb-like structures grow in the 
axils of ordinary leaves, for example, in the tiger lily ; 
these drop off when they are ripe, and can grow into 
whole new plants. They are really half-way between 
bulbs and true buds. 



CHAPTER XV. 



FLOWERS 

IF you have ever noticed a pea-flower fading, you will 
have seen that from its heart there grows a little green 
pea pod which ripens till there are full-grown peas in 
it (see fig. 80) ; and a yellow dandelion flower turns in 
the end to a white puff ball which scatters a hundred 
floating fruits. In fact, almost all flowers which have 
not been spoiled by the gardeners and " over-cultivated " 
leave in their place when they die fruits and seeds in 
some form or other. This gives us the key to the secret of 
the structure of the flowers themselves. They are the 
forerunners of the fruits, containing living seed, and 

their structure and all their 
parts are adapted in some 
way to help in the forma- 
tion of fruit. Now let us 
examine the flowers, never 
forgetting that fact. 

Let us choose, for ex- 
ample, a harebell. On the 
outside we find five separ- 
ate green parts, and if we 
examine a bud which has 
not yet opened we shall 
find that these fold quite 
tightly over the inner por- 
tions " of the flower and 
protect them, as they do 
in the rose and in almost all flowers (see fig. 69). In 
this they correspond to some extent to the bud scales, 




CHAP. XV. 



FLOWERS 



79 




and their special work is that of protection. In all hare- 
bells and roses there are five of these parts, but in the 
wallflower you will find only four, 
and in poppies two, and so on. 
There are different numbers of 
them in the different kinds of 
flowers. They are also of different 
shapes and sizes ; sometimes each 
of the five parts is free, and some- 
times they are all joined up together 
to form a true cup, as in the prim- 
rose (see fig. 72). These outer 
green protective parts have a special 
name, and are called the calyx or 
cup, while each of the separate 
parts which makes the cup is 
called a sepal. 

Directly within the calyx we 
come to the parts which are gener- 
ally bright and prettily coloured, 
and which give the chief beauty to 
the flower. In the harebell which 
we are examining these parts are 

joined up to form a bell, but in the rose they are each 

separate (see fig. 71). In both harebell and rose we find 

five of these parts, and the same 

number in the primrose, where 

you will find that they are joined 

up at the base to form a long, 

narrow tube, and then spread 

out separately like those of a 

rose. Both in the harebell and 

primrose, where they are joined 

up, we can tell the number of 

parts which go to make the 

whole bell or tube (and this is 

nearly always the case in bell flowers), while, of course, 

where the parts are free it is quite easy to count them, 



Fig. 70. Buds of the 
Rose ; A with the calyx 
covering the inner parts, 
B with the petals opening 
out. 




Fig. 71. Flower of the Rose, 
with separate petals. 



8o 



FLOWERS 



CHAP. XV. 




the tube formed by the petals. 



and we find that for each kind of flower their number 
is always fixed. For example, we find five in the hare- 
bell, rose, primrose, and many others, four in the poppy, 

wallflower, cress, and so on. 
These parts are called the 
petals, and in almost all 
flowers you will find that 
they are bright and pretty, 
and stand out from the sur- 
rounding green leaves, so 
that they are easily seen. 
When the cups or bells hang 
down they may protect the 
parts within from the rain, 
but that is not generally 
their chief work The first 

duty of the petals IS to 06 

attractive. You will under- 

stand better why this is so after we have gone further 
into the flower. 

Within the petals, and, in most cases, lying at the 
base of the bell, you find several yellowish dusty sacs, on 
fine thread-like stalks. In most flowers they are all free 
from each other and from the petals, 
but in the primrose they are fastened 
to the tube of the petals (see fig. 72). 
In some flowers you will find a great 
many of these, as you do in the wild 
rose (see fig. 71) and the poppy, where 
there are so many that you can hardly 
count them. In other flowers there are 
very few; for example, there are only 
two in the blue speedwell (see fig. 73). 
In most flowers the single stamens, as they are called, 
are very much alike in their structure, and they all have 
the same work to do. Look at these structures in a 
tulip or lily, where they are very big, and carefully pull 
one off and examine it (fig. 74). You will find that it 




Fig. 73. Flower 
of Speedwell, with 
only two stamens (s). 



CHAP. XV. 



FLOWERS 



81 



A 




Fig. 74. Single 
stamen from Tulip 
flower ; A, anthers, 
or pollen sacs ; F, 
filament, or stalk of 
stamen. 



consists of a stalk which we call the filament, with two 
long sacs at the tip which hold the yellow dust, and 
which we call the anthers. If you examine a fully 
blown flower of the tulip or lily, you 
will find that the sacs split open right 
down their length and let out a fine 
yellow powder. This powder is the im- 
portant thing about the stamens, and is 
called the pollen. In all stamens you 
will find the anthers or pollen sacs, 
while the stalk, which is less important, 
is not always developed. Sometimes the 
sacs split right open like those in the 
lilies, but there are other ways of open- 
ing; as for instance, in the rhododen- 
dron you will see a little round hole at 
the tip of each anther, which lets the 
pollen shake out like pepper out of a pepper-pot. 

Now we have come to the heart of the flower, and find 
there the most important thing in it. Examine a sweet 
pea, for example, and 
you will find in the mid- 
dle of the flower a tiny 
green structure very like 
a pea pod, with a little 
sticky knob at the tip. 
In the heart of a tulip 
you will find a long green 
box with a sticky, three- 
cornered knob at the top 
(fig. 75), while in a butter- 
cup there are a number 
of these structures in- 
stead of one (see fig. 765), 

each of which has very much the appearance of a little 
pea-pod. Open the pea-pod, or the box of the tulip, 
and you will find within it a number of very small balls 
of a clear green colour. T hese are the young structures 

( C 260 ) G 




Fig. 75. Flower of Tulip laid open, 
showing the three-cornered central green 
box containing the young seeds. 



FLOWERS 



CHAP. XV. 



which will become seeds when they are older, and they 
are the most important things in the flower. The green 

box which protects them 
is called the carpel in the 
case of the pea-pod, where 
there is one space in it. In 
the tulip you will find that 
the box is divided into 




Fig. 76. Buttercup flower laid open, 
showing that there are many seed-boxes 
(s) in the centre of the flower. R, the 
receptacle is the swollen end of the 
flower stalk. 





Fig. 77. Carpels of 
the Tulip cut open to 
show that there are 
three spaces with seeds, 
each division represent- 
ing a single carpel. 



three compartments, and 
each of these is called 
a car- 
pel (see 

fig- 77). 

You may think of the tulip carpels as 

being the same thing as three pea-pods 

joined very tightly together. Some 

flowers have only one carpel ; others 

have three or five joined up like those 

of the tulip, while others like those 

of the buttercup have a very large 
number of single 
separate carpels. 
In the pea, 

tulip, buttercup, and many others, 
the carpels are in the centre of 
the flower, above the petals, and 
attached to the swollen end of the 
flower stalk, which is called the 
receptacle, as in fig. 76 R. Other 
flowers have the receptacle hol- 
lowed out like a cup or goblet, 
and the carpels sunk right in it. 
When this is the case, we generally 
find that the sepals and petals lie 
above the carpels and not below 
This is also the case in the rose, 

where in fig. 70 flower B shows clearly the swollen 

part below the bud, which is the hollowed receptacle 



Fig. 78. Flower of 
Cherry cut open to show 
the hollowed receptacle, R, 
below the level of the 
petals, and containing the 
carpel, C. 

them, as in fig. 78. 



CHAP. XV. FLOWERS 83 

containing the carpels, and the same is true of the 
harebell (see fig. 69) and many flowers. 

What can be the use of the sticky tip that we found 
on the carpels ? Examine the tip of the carpel of a lily 
which is well open, and you will very likely find some 
of the yellow pollen sticking to its surface. It is a 
curious fact that the little structures within the carpels 
which will become seeds cannot ripen into true seeds 
unless they are waked up to growth by the pollen grains. 
The sticky tip of the carpels (or stigma, as it is called) 
catches the pollen grains and holds them ; then they grow 
down into the carpels and carry with them the nuclei (see 
p. 92) that enter the undeveloped seeds. These stir the 
cells to divide, and after many divisions the embryos are 
formed and the seeds ripen. Sometimes the stigma has 
a long stalk which places it in a good position to catch 
the pollen grains. This stalk is called the style y and is 
to be found in many flowers (see fig. 72). 

The pollen dust is fine and light, and may be carried 
by the wind on to the stigma, as it sometimes is in 
poppies, and always is in pine-trees ; but this is rather 
a wasteful way, because the wind blows so irregularly 
that very much pollen is lost and never reaches the 
stigma. In order to save some of this loss, and to make 
the pollinating more certain, flowers have arranged their 
parts so as to make use of the help of insects. You 
know that very many flowers have sweet honey in them 
which the bees like, and come to collect, going from 
flower to flower to do so. When the bee settles on the 
flower it gets covered with the pollen dust, and then 
when it goes to the next flower and walks over it, it is 
almost sure to leave behind it some of the pollen stick- 
ing on the stigma. Of course, in this way also some 
pollen is lost, but insects are far more reliable than the 
wind. We now see the use of the bright coloured 
petals ; they help to attract the bees to the flower. The 
flowers have made the bees and other insects their 
special carriers of pollen, and they pay the insect with 



84 FLOWERS CHAP. XV. 

honey, and some of the surplus pollen. Bees generally 
go from flower to flower of the same kind on any one 
day's journey, so that the flowers get pollen from others 
of their own kind. This is important, for " foreign 
pollen " (as the pollen from quite different kinds of 
flowers is called) does not help the young seeds at all. 

We have now found a use for all the parts of the 
flower. 

There are many special things about flowers which 
we must leave till later on, but we may just notice now 
how some are regular, like the primrose, rose, poppy, 
and so on, which are after the pattern of a circle, and 
appear the same from whichever side you look. Others, 

like the violet, larkspur, or 
sweet pea, are not regu- 
lar, but have only two 
sides alike. This differ- 
ence is very often due to 
some special structure of 
the flower in relation to 
the insects which visit it, 
Fig. 79. A, violet, a two-sided flower, and if you examine and 

B. Primrose, a circular flower. Compare the two-sided 

with the circular flowers 

you will generally find that the two-sided flowers are 
the more complicated. Some of them become very 
complicated indeed, like the orchids, which have such 
strange flowers, and in which the relation between the 
insects and the flower has become very special. 

We must leave these more complicated cases till 
Chapter XXII., and come back to the simple important 
facts about the work which all flowers have to do. They 
must make sure that in some way or other, seeds 
are formed for the plant. If the flower does not do 
this, then it is not doing the work for which it was 
made. 

You will find a number of flowers in gardens which 
do not do their work properly, and very often have no 





CHAP. XV. FLOWERS 85 

seeds at all,but they are speciallycultivated by gardeners 
to do other things. For the study of the true structures 
of flowers, it is generally better to examine wild flowers 
instead of garden ones, which are often much altered 
by the rather unnatural conditions in which they are 
made to live. 



CHAPTER XVI. 
FRUITS AND SEEDS 

WITHIN the flowers we saw, protected and shut in, 
the carpels or seed-box, within which are the very 
young structures which will become seeds. Now let 
us watch them develop. In such flowers as the sweet 
pea, for example, in summer-time, this will not take 
very long. Mark a special flower, and watch it each 
day; you will find the little green pod will gradually 
grow bigger, till it splits away the petals which are 




Fig. 80. A, Pea-flower. B, the same beginning to fade, with the ripening 
carpel breaking through the keel. C, the same carpel much enlarged, the 
petals and stamens quite faded. 

beginning to wither, and pushes out between them. 
As the pod gets larger you can see the seeds within 
growing too, if you look at the pod carefully against the 
light. The stigma does not grow any further, as its 
\vork was finished when it had caught the pollen grains. 
After a time the petals and stamens drop right away, 
and only the calyx remains ; it does not grow very 
much, but it keeps fresh and green for some time, as it 
has still to act as a cup to hold the pod. It only takes 



CHAP. XVI. FRUITS AND SEEDS 87 

a few days for these things to happen, then till the pea 

pod is quite ripe may take a week or two more. The 

pod continues to grow and turns yellowish brown and 

dry, then one day when the sun is warm you may see and 

hear it split 

open sud- 

denly down 

its central 

ridge, and 

shoot out the brown, dry seeds. Then 

the work of the flower is quite over, 

and the seeds have started to make 

their own way in the world. 

Let us pick a nearly ripe pea-pod 
and examine it; it is the ripe carpel, Fig.si. A,ripecar- 
with several ripe seeds in it, and to- od.' f Bf a pd "sucu 
gether they form what is called a fruit. den iy ^ and twist - 





,1 f ,1 j 1 1 // e - n -A. ed U P. scattering the 

In the case of the pod the " fruit it- see ds 

self is a dry pea-pod husk, but in other 

plants the fruits may be very different. Examine a 

marrow, for example. Watch it in the course of its 

trowth, if possible, and you wiii find that the marrow 
ower is one of those with its seed-box below and out- 
side the calyx and petals. As the marrow ripens this 
swells with the food stored in it, and the many growing 
seeds, till the flowers are only small shrivelled structures 
at one end. If you then cut the ripe, or nearly ripe, 
marrow fruit across, you will find that its wall is very 
thick and fleshy, and that the many seeds are buried in 
a soft pulp. The melon shows us just the same thing. 
Such fruits seldom split suddenly to shoot out their 
seeds (though some foreign ones do); they depend 
more on animals which may eat them and so scatter the 
seeds about. 

In all cases it is better for the plant to have the seeds 
scattered so that they do not sprout too near together, 
but have room enough to grow without crowding each 
other out. 



88 



FRUITS AND SEEDS 



CHAP. XVI 




Fig. 82. Cherry 
fruit cut open, 
showing the flesh 
(/), stone (s), and 
seed S. 



In the pea and marrow there are many seeds, but 
there are large numbers of fruits in which we find only 
one. For example, in plums, cherries, and peaches we 
have a fleshy outer fruit-case with a stony lining cover- 
ing over one large seed. Such fruits do not open, for 
there is only one seed within, and so the 
fruit is scattered whole. These fruits 
nearly always get scattered by animals, 
for the flesh is very sweet and attractive 
to eat, and then, as a rule, they get rid of 
the stone (which contains the seed) at 
some distance from the parent. 

Sometimes we find a number of fruits 
just like the cherry clustered together, 
only instead of each of them being large, 
they are all very small, so that the whole 
cluster of fruits may be the size of a single cherry. 
This is the case in the common blackberry and the 
raspberry, where each of the little fruitlets really corre- 
sponds to a cherry. 

Then there are many fruits which belong to quite 
a different class, and arrange to 
scatter themselves by the help 
of the wind, such as the fruits 
of the dandelion, thistle, and 
many others, which have light 
41 parachutes," and therefore 
blow away with the least puff of 
wind when they are ripe and 
dry (see fig. 83). 

Other fruits like the sycamore 
have big side-wings which catch 
the wind as they fall, and get 
twirled for some distance. In these cases each of the 
separate parts which flies is really a fruit, only in the 
case of the dandelion, thistle, and many others, each of 
these fruits contains only one seed, and the fruit itself 
is so small and dry that we get into the way of speaking 




Fig. 83. A, head of Dandelion 
fruits, with most of them scat- 
tered. B, single Dandelion 
fruit. 



CHAP. XVI. 



FRUITS AND SEEDS 



89 




Fig. 84. Fruit 



of the whole fruit as a " seed." This is not correct, 

however, because even though there is only one seed 
present, yet it is surrounded by the dry 
remains of the ripe carpel, and is therefore 
a fruit. 

Simple seeds which have wings are rather 
rare, but we find them on pine seeds (see 
fig. 125), and the seeds of the willow herb 
are covered with a number of silky hairs, 
which make them so light that they fly in 
the wind. If you watch a spray of willow 
herb ripening, you will find that the old 
carpels, or fruits, split up into four parts 
and let out a number of fluffy white seeds. 
These are true flying seeds (see fig. 84). 

Other seeds get scattered by the wind 
although they do not fly. For example, in 
the poppy the fruit is the hardened ripe 
carpels which have become quite dry, and 
together look like a little round box, within 
which there are many tiny dry seeds. 

When the box or capsule is quite ripe 

openings come in it, just below the 

projecting top, and then, when the 

weather is dry and they are open, a 

strong wind may bend the stalk of the 

fruit and shake the capsule strongly. 

The seeds come scattering out like 

pepper from a pepper-pot, and may 

get carried some distance from their 

parent plant (see Plate II. and fig. 

85). 

Some fruits are covered with spines 
and hooks, which catch on to the 
wool of animals, and so get carried 
quite a distance before they are 
dropped. This gives the seedlings a good chance of 
reaching a new spot where they can grow away from 



and allowing 
toesc y ape g sc 




Fig. 85. Ripe Poppy 
capsule, showing the 
little pores at the top 
which let out the ripe 
seeds when the capsule 
is shaken. 



FRUITS AND SEEDS 



CHAP. XVI. 



the parent, and so not be too crowded. Well-known 
fruits of this kind are the burs, which stick tightly to 
one another with their dozens of little 
hooks, the " bur" being really a cluster 

of many fruits together. 

Simple fruits of the same 

kind are the bidens, each 

with its two long spines, 

and the small fruits of 





Fig. 86. A Bur, 
which is a cluster 



the goose grass, which 



Fig. 87 
: (& 



Simple 
of the 



of hooked fruits. 



fruits 

Goose grass with its 

hooks ; (6) the Bidens 

with its harpoon-like 

spines. 



are covered with the finest 
hooks. 

Quite a special kind of fruit is the 
strawberry, which, as you know, has a thick fleshy pulp 
covered with a number of small, yellow " seeds." In 
reality, each of these " seeds " is a whole fruit, and the 
thick flesh which we eat is the 
swollen end of the flower stalk which 
we call the " receptacle." Therefore 
a strawberry really consists of a large 
number of fruits and a piece of stalk 
which is altered to form the fleshy, 
attractive mass which induces birds 
and people to eat the whole, and so 
scatter the little dry fruits. 

There are very many other kinds 
of fruits which all have special de- 
vices to make sure that their seeds 
are scattered, and all proper fruits 
have seeds in them. But, just as we 
found that some garden flowers are 
grown only for their beauty, and do not set any seed, 
so we find that some fruits are grown specially without 
any seeds, such as bananas and some oranges. Such 
fruits are the result, of our liking to eat the soft, sweet 
pulp without the trouble of the seeds, but such fruits 
are of no use to the plant. 

Now let us look at the structure of the ripe seeds 




Fig. 88. Strawberry. 
Each of the little " seeds " 
is a whole fruit, and the 
"flesh" the swollen re- 
ceptacle. 



CHAP. XVI. 



FRUITS AND SEEDS 




B. 



Fig. 89. A, outside of Bean; (/) black 
scar showing where the bean was attached 
to the pod ; (r) ridge made by young root ; 
B, bean split open ; (n) nurse leaves ; (/>) 
embryo ; (a) scar where the embryo was 
separated from the nurse leaf on that 
side. 



themselves, and see how they are fitted to go out alone 

into the world prepared 
to make a new plant. 
Seeds are all very much 
alike in the important 
points of their struc- 
ture, although they vary 
much in the shape, size, 
and colour of their 
parts. We already 
know what beans are 
like from our careful 
study of them at the 
beginning of our work 
(see Chapter III.), and 
beans show us particu- 
larly well all the important parts of a true seed, so that 
we may take them as be- 
ing typical of one large 
family of flowering plants. 
The maize embryo (see 
p. 10) istypicalof the rest 
of the flowering plants. 
In the ripe seeds oi both of 
these groups (you should 
examine them again if 
you have forgotten any 
of the facts) w r e find that 
the important thing is the 
baby plant, which is sup- 
plied with food and pro- 
tected by two seed coats, till it is time for it to grow out 
and form a new plant like its parent. 




Fig. 90. A, outside of 
Maize.showing the embryo 
(e) on one side; B, sprout- 
ing, showing the root (r) 
and shoot (s) ; C, the same 
further grown. 




CHAPTER XVII. 



THE TISSUES BUILDING UP THE PLANT BODY 

IN our study of plants up to the present, we have only 
looked at their structures from the outside. We have 
examined the form, uses, and life of the parts of their 
bodies without looking for the details which might 
answer the question " How are they built up ? " Just 
as a house as a whole has a definite form, with rooms, 
and doors, and windows, each with their definite form 
and use, and at the same time every one of these things 
is built up of small separate bricks, tiles, pipes, and 
pieces of wood : so we find that the whole plant is com- 
posed of a number of definite parts, which are them- 
selves built up of tiny individual parts, which we may 
take to correspond with the bricks of a house. Of 
course, they do not do this completely, for a plant is 
a living thing, and is far more complicated than a house, 

and each of the tiny indi- 
vidual parts is also a living, 
growing thing. These little 
building structures are call- 
ed cells both in plants and 
animals, and they are so 
very small that you cannot 
study them fully without 
a microscope, and that is 
a very complicated and ex- 
pensive thing, so we will 




Fig. 91. Two cells from plant tissue, 
(c) Living contents; () cell nucleus; 
(v) spaces filled with sap ; (w) wall of 
cell (much magnified). 



leave it alone and only 
study what we can see of the structure of plants without 
it. Try, however, just to see a few cells under the 



CHAR XVII. 



THE TISSUES 



93 



microscope, so as to know what they are like. A typical 
cell has a wall, within which is the actual living sub- 
stance, a clear, jelly-like mass, which contains many 
granules of food and stored material. Within this living 
substance is a more solid mass of still more actively 
living substance, which is called the nucleus. Cells like 
these, or cells which were like these when they were 
young, and which have become modified for special 
work, build up the whole plant body (see fig. 91). 

You can get a good hand magnifying-glass for several 
shillings, and with this and a very sharp knife, you can 
find out something of the structure of 
the insides of plants, even though most 
of the cells are so small as to be out of 
sight except when looked at through a 
microscope. 

Let us first cut as thin a slice as pos- 
sible across a water-lily stem, and put 
it on a small piece of glass and hold it 
up to the light. Examine it with the 
magnifying glass, and you will see that 
it is not a solid mass of tissue, but that 
it is built up of a fine network like lace, 
with quite large spaces between the 
threads (see fig. 92). These spaces are 
air spaces, and the fine lace-work threads 
are meshes built up of single rows of 
cells, which you may be able to see if your glass is a 
good one. Cells may be packed loosely like this, or 
they may be in more compact form something like a 
honeycomb, as you may see in the pith of an elder twig 
and many other stems. You can crush these soft cells 
between your fingers, and we cannot imagine that they 
could build up the hard, firm branches of trees. 

Now examine the stem of a seedling sunflower, by 
cutting a very thin slice across it ; you will see in it a 
ring of strands where the cells are smaller than those 
of the soft tissue and also much more closely packed 




Fig. 92. Piece of 
thin section across 
Water-lily stem, 
showing mesh-work 
tissue seen with a 
magnifying glass. 



94 



THE TISSUES 



CHAP. XVII. 





Fig- 93- P^ce ot 
the stem of a seedling 
Sunflower cut across, 
showing strands of 
"water-pipe" cells. 



Fig. 94. Piece 
of stem cut a- 
cross and then 
split lengthways, 
showing the 
strands of thicker 
"water-pipe" 
cells. 



(see fig. 93). Then cut a thin slice longways down the 
stem, and you will see that these more solid strands are 
the cut ends of long strings of such 
tissue which run through 
the stem. The cells which 
build up these strings are 
not quite ordinary cells, 
but are exceptionally long, 
like water-pipes, and they 
have thickened walls. 
These cells do the carry- 
ing of water and liquid 
food up and down the 
plant (see fig. 94). 

You can see that the 
water travels up these cells if you cut 
across a stem near the root and place it in a little red 
ink. After a few hours if you cut a section several 
inches from the bottom of the stem you will find that 
these strands are coloured red by the ink which has 
passed through them, while the rest of the stem is very 
little coloured, or quite colourless. This shows us that 
these strands are the special water-pipes of the plant. 

Large numbers of such cells 
closely packed together, and 
with some other hard cells be- 
tween them, make up the wood 
in woody stems. Cut across 
a small twig of lime or oak 
and examine it with your lens. 
Outside is the brown bark, then 
within that some green cells 
and a little soft tissue, while 
most of the stem is made up 
of a mass of hard wood cells, 
among which you can see some 

of the larger water vessels distinct from the rest. All 
this hard tissue really corresponds to the joined up 




Fig. 95. Cross section through 
a Lime twig three years old seen 
with a magnifying glass. 



CHAP. XVII. THE TISSUES 95 

separate strands which we saw in the sunflower stem 
(see fig. 95). Trees like the lime and oak, which live for 
a long time, grow for a certain amount every year, and 
each year they add a ring of wood to their stems. In 
old stems you can see clearly the rings of wood which 
have been formed by each year's growth. This is an- 
other way of telling the age of the stem, and you should 
compare your results from this method with those you 
got from counting up the bud scars (see p. 75). 

Leaves, as you know, require much water, which 
comes to them up the stem through the " water-pipes." 
You saw already the course of the water-pipes in leaves, 
for they are the " veins" which we found sometimes 
make a complete network, and sometimes run parallel 
in the tissue of the leaf. If you put a leaf stalk in red 
ink, you will see that the veins are connected with the 
water-pipe strands in the stalk, for they will both get 
coloured by the ink as it passes along them. 

Just as in animals the whole body is covered over 
with a skin, so in plants we find a special outside sheet 
of cells, which protect the inner tissues and form a thin 
skin. You can get this off very well if you break across 
an iris leaf, and pull along the thin, colourless layer on 
the outside. If you examine it with your lens, you may 
perhaps see something of the mosaic-like pattern of the 
cells which build it up. You should certainly see that 
it is colourless, although the tissue of the leaf beneath 
it is quite green. 

On the large branches of trees and the bigger plants, 
we do not find this delicate protecting layer, but instead 
there is a thick brown cork. When the cork layer gets 
very thick it splits irregularly as the tree grows too big 
for it, and so forms a rugged bark. The cork layers 
have much the same duty as the fine skin, only they are 
thicker and stronger, and more suited to hold out 
through the winter. You know already from daily life 
the practical use of cork, for you put it into bottles to 
keep the liquid in the bottle and the damp and dust 



96 THE TISSUES CHAP. XVII. 

in the air from entering. Just what the cork does for 
the bottle, the sheets of cork wrapping round the 
branches do for the plant. They prevent it from being 
dried up by cold winds, and they keep out the heavy 
rains of winter which would injure it. Roots have a 
cork coating also when they get old. As you may 
remember, it is only the tip of the root which can absorb 
water for the plant, so that in the young part of the root 
a cork layer would be very much out of place, and you 
will never find it there. You will find instead the little 
delicate root-hairs, which absorb water and pass it on to 
the older parts ; these old parts do no more absorbing, 
they are only the water carriers and food storers, and so 
have no hairs and are protected by a layer of cork. 
As we found before, plants breathe in air like animals, 
and you may ask how they can do this 
when they are covered with their thick air- 
tight layers of cork. Examine a fairly old 
elder twig, and you will see all over its 
brown skin numbers of darker brown spots. 
If you look at these with your magnifying 
glass, you will see that they are quite 
spongy and soft. They are the special 
entrances for air, and are the breathing 
spots or lenticels (see fig. 96). They are to 
taigi De found in all corky stems, although they 
showing the are not always so easy to see as in the 

breathing pores ij 
in the bark. elder. 

On the leaves and stems of many plants 
you will find a large number of hairs. In some cases 
there are so many as to make the whole plant quite 
woolly, like the mouse-ear leaves. These hairs are pro- 
tective, and keep the leaf warm and dry, and in some 
cases may shelter it from the sun. Hairs may consist 
of one cell, or several in a row, or of cells which are 
branched in a complicated way. Certain hair- cells 
protect the plant by stinging, as you can see if you 
watch a nettle-leaf with your magnifying-glass, and then 




CHAP. XVII. THE TISSUES 97 

rub your finger along it, only touching the hairs. You 
will find that it is they which sting you, and not the 
leaf itself. 

Now we have found several kinds of tissues in plants, 
the skin and cork covering all over and protecting the 
rest ; the central vessels or watet-pipes, corresponding to 
the veins and arteries of animals, the soft white ground 
tissue, which in some stems may be very loosely packed, 
and the soft green tissue in the leaves and young stems, 
which we found was the food-manufacturing part of the 
plant. There are also strands of simple strengthening 
tissue^ both by the water-pipes and in separate bundles 
in the soft tissue ; these we may take as representing 
the bones of animals. 

We have noticed (Chapter VIII.) that plants are 
sensitive to light and bend towards it, that they feel 
heat and cold, and that the stem and root seem to know 
when they are growing in the right or wrong positions, 
and bend accordingly. We know that we ourselves 
and the animals recognize such things by the help of 
nerves which carry messages to the brain. But where 
is the brain in plants, and the nerves ? No true nerves 
have been found in plants, and it seems as though 
different parts of the plant were specially sensitive 
without there being any <( brains." So that we cannot 
speak of a central nervous system in even the highest 
plants as we can in the animals. In this respect they 
are built on quite a different plan from animals. 



(C260) 



PART III. 

SPECIALISATION IN PLANTS 



CHAPTER XVIII. 
FOR PROTECTION AGAINST LOSS OF WATER 

IF you go along the lanes and in the gardens in the 
height of summer when it is hot and dry and the sun 
beats on the plants all day, you may see them beginning 
to wither for want of water. The roots are not able to 
find enough moisture in the soil to supply the leaves, 
which, being in the hot air, continue to transpire away 
the water resources of the plant, so that in the end each 
of its cells must suffer and the whole become limp and 
droop. This happens because the ordinary green plants 
of our country make no special preparation for such 
dry weather. Our hot season is short, and even in the 
summer we have frequent showers which keep the soil 

moist enough to provide the 
plants with water from day to 
day, so that they have not 
become accustomed to long 
periods when there is no pros- 
pect of rain. 

Compare one of our usual 
green plants, a sunflower, for 
example, with such a thing as 
a cactus, which you may get 
growing in a pot of dry sand. 
The cactus is able to withstand 
the hottest sun for days, though 
it gets very little water, and 
sometimes apparently none at all ; yet it does not wither, 
but grows, and may bear the most lovely flowers. From 

99 




Fig. 97. A Cactus, with needle- 
like spines for leaves, and a thick 
green stem. 



TOO AGAINST LOSS OF WATER CHAP. XVIII. 

travellers we learn how the huge cactus plants grow in 
dry and stony deserts, standing every day in the blazing 
sun. Such is, of course, their home, and they are used to 
it ; but how is it that they are able to flourish under 
conditions which would kill one of our own green 
plants ? 

Let us look at their structure and see in what they 
differ from a usual plant. First, they have no green 
leaves, for these have developed into spines (see p. 62), 
while the sunflower has many large ordinary leaves. 

You will remember that the surface of leaves is con- 
tinually giving off water from its many pores. When a 
plant has a number of big leaves this transpiring area is 
large, while when it has no leaves at all, but a thick, 
green stem instead, then the amount of surface from 
which water vapour is being given off is very much 
reduced, even though there may be about an equal 
quantity of actual tissue in the two plants. You can 
see that this is the case if you take a ball or thick block 
of dough and roughly measure its surface, then roll it 
out till it is fairly thin and measure it again ; you will 
see that the thinner you roll it the more surface there 
is ; all the time, of course, the amount of actual dough 
remains the same. So that of two plants of the same 
bulk, the one with broad, thin leaves will expose the 
most surface to the air, and so lose more water than one 
with very thick leaves or none at all. The latter would 
therefore be better fitted to live under dry conditions. 

But, you may say, leaves have a definite work to do ; 
how can the plant live without them ? In the cactus 
the thick stem is green and does the work of food 
building ; naturally it cannot do so much for the plant 
as many big leaves could, but it does enough to allow it 
to live and grow slowly and surely for many years, 
though it cannot grow in each year nearly at the same 
rate as can the sunflower. If you cut through the stem 
of a cactus you will find that its skin is very thick and 
tough, and this thick coat protects the plant against the 



CHAP. XVIII. AGAINST LOSS OF WATER 101 

fierceness of the sun far more completely than the thin 
skin of a sunflower does. At the same time, the tissues 
of the two stems are different ; the sunflower is hollow 
and delicate, but the cactus is very thick and juicy, and 
each cell contains much gummy stuff which has the 
power of holding water strongly. So that we see in 
many important points the structure of a cactus is 
different from that of a usual green plant, and is 
specially suited to the dry conditions of the desert. 

Many desert plants are built on the plan of the cactus, 
but there are also others which are not at all like them, 
and yet they are able to live in deserts and very dry 
places. If you examine them, however, you will find 
that they all have some special way of protecting them- 
selves from being dried up. Some of them have hard, 
dry, woody stems, well protected by corky layers, and 
they only put out green leaves in the rainy season, and 
lose them directly the hottest weather begins. Others, 
which grow from seed every year, learn to sprout, flower, 
and fruit very quickly while there is some moisture, and 
they form well-protected seeds, which wait till next 
rainy season. One very curious desert plant has only 
two leaves, which last it the whole of its life, and which 
are very hard and leathery. There are endless varieties 
of things which the plants may do to protect themselves 
from being dried up, and we can only look at a few 
special examples. 

To find plants growing in desert places we do not 
not need to go out of England, because from the point 
of view of the plant, one which is growing on a dry rock 
or on a patch of bare dry sand, is really growing in a 
little desert. For it the supply of water is the chief 
problem, even though we never get hot tropical sunshine 
in England. Look, for example, at the plants growing 
on the sand dunes which are very like deserts in appear- 
ance, and the plants on dry walls, or on the " screes " of 
broken rock at a hill foot ; they are all growing in deserts. 

In many cases plants growing in such positions have 



102 



AGAINST LOSS OF WATER CHAP. XVIII. 




Fig 98. Thick fleshy 
leaves of Stone-crop. 



small thick leaves, nearly round, or shaped like sausages, 
so that they have much water-storing 
tissue in proportion to a small transpir- 
ing surface. This is the case in the 
stone-crop (see fig. 98) and the house- 
leek, where each separate leaf has fol- 
lowed the same principle as the cactus 
stem, and exposes relatively little sur- 
face to the air. Such 
plants frequently 
have very long roots, 
which penetrate 
deeply between the cracks of the rocks 
and find hidden sources of water. 

Other plants, instead of having 
leaves of this type, have exceedingly 
small leaves which may soon drop 
off, while the stem is green and does 
some of the food building. Small 
leaves are assisted by the green stem 
in gorse (fig. 99), which often lives in 
very dry places, though it can grow 
equally well under usual conditions. 
Many plants roll up their leaves 

when it is dry, so that the 
surface with trie transpiring 
pores is on the inside, and 
protected by the outer side 
with its hard skin (see fig. 
100). In damp weather 
these leaves unroll, and do 
alltheworktheycan. Leaves 
like this are to be seen in 
many of the grasses, par- 
ticularly those growing on 
sand dunes and moorland ; 
while a number of the heaths and heather do the same 
thing to protect their transpiring surfaces. 




Fig. 99. Gorse, with 
green stem which does 
the work of leaves. 



B 



Fig. loo. Leaf of the Sand-grass. 
A, rolled up ; B, open, (a) and (6), 
sections across the same. 



CHAP. XVIII. AGAINST LOSS OF WATER 103 

You will find that in nature, water is one of the most 
important things in the surroundings of plants, and in 
their struggles to get it and keep it they have changed 
their forms in many ways, and in some cases have 
become extraordinary-looking creatures as a result. 



CHAPTER XIX. 
SPECIALISATION FOR CLIMBING 

IF you go into a wood, or even a thicket, in summer, 
you can see how the leaves of the big trees make, what 
is for us, a delightful shade. But look at the ground 
under these tall trees, at a place where they are growing 
thickly together, and you will find that there are very 
few plants below them, and that the earth is almost bare 
except for dead leaves, twigs, and a few mosses. In 
deep pine-woods there are great patches without even 
the mosses, where are only dead pine-needles and some 
toadstools. You can well understand, when you re- 
member how very important light is for the plants, that 
it is too dark for them to grow under the heavy shadow 
of thick trees. Even in gardens you may see how the 
tall, quickly growing plants kill off the smaller ones 
beneath them. 

When many plants are growing together, it is easy to 
see that the taller ones get most light, but if a plant 
grows very tall it requires a strong stem to hold it up- 
right, and that means the building of a large amount of 
wood which takes a quantity of material, so that the 
growth must be slow and costly. 

Some plants, however, have learned to grow up into 
the light without building a firm stem for themselves, 
because they use instead the support of other plants, 
and especially of trees. You must often have noticed 
in a wood great sprays of honeysuckle sprawling high 
up over the trees; sometimes one of the festoons of 
honeysuckle may lie over the branches of several trees., 



CHAP. XIX. SPECIALISATION FOR CLIMBING 105 

and so get into the best positions for the light. The 
Travellers' Joy, or white clematis, grows all over the tall 
hedges, and may sometimes completely smother a young 
tree, so that one can see nothing but the leaves and 
light green and white flowers of the clematis. Then, 
too, there is the ivy, which you know may sometimes 
grow up trees to a very great height, covering over the 
leaves so that the whole looks like a giant ivy bush. 
These plants all get their support from trees, which 
have built themselves strong stems. Pull down a big 
branch of honeysuckle or Travellers' Joy from the sup- 
porting tree-trunks, and you will see that it cannot 
remain upright but falls limply to the ground. It is 
true that these plants have some wood in their stems 
sometimes clematis and ivy may have woody stems 
several inches thick, but they are never strong enough 
to support the weight of the crown of leaves and 
branches. By clinging to others in this way these 
plants can economise much building material and reach 
the light far quicker than they could do otherwise. 

If you examine their wood, you will see that it is not 
quite like that of usual plants. Cut through the stem of 
a clematis which is about an inch thick, and even before 
you look at it with a magnifying-glass you will see 
how very loosely built the wood is, with wide rays of 
soft tissue and very large water vessels. It is not built 
for strength and support, but merely to carry supplies 
of water up to the leaves, for although these plants use 
trees as supports, they do not get anything more from 
them, and must supply themselves with all else they 
need. You may often see that the central part of the 
wood is not in the true centre of the stem, but is pushed 
to one side, and the rings of the year's growth are very 
irregular, being much more to one side than to the 
other. This is because they lean against the supporting 
branches, and so must grow chiefly on the side away 
from them. Sometimes as the ivy grows right round 
the support, it will grow more, first on one and then on 



io6 



SPECIALISATION FOR CLIMBING CHAP. XIX. 




Fig. 10 1. Adven- 
titious roots growing 
out from the stem of 
Ivy between the leaf 
stalks. 



the opposite side of its stem, and so the centre does not 

remain in one place, but shifts round. 

The other parts of these woody climb- 
ing plants are but little out of the com- 
mon. They have merely learnt to econo- 
mise their own stem-material, and at the 
same time to reach a good position in 
the light, so that it is in their stems that 
we find their chief differences from usual 
plants. The honeysuckle and clematis 
have no special climbing organs, but the 
Ivy has clusters of adventitious roots 
which come out from the back of its 
stem, and hold it on to the support (see 
p. 56 and fig. 101). 

In climbing plants in 
which the above-ground 

parts live only for one year and then die 

down, we do not get a woody stem. 

Such soft green plants as the hop and 

convolvulus, for example, are entirely 

dependent on others for their support. 

They have specially sensitive tips to 

their stems, which feel the support and 

definitely twine round it in a close spiral, 

which clings ever closer to the support 

as they grow (see fig. 102). 

Climbers of this kind have only modi- 
fied their stems ; the rest of their parts 

are not in any way specially altered by 

this habit. 

Some plants which sprawl about on 

others hold themselves up by the power 

of clinging and twining in their leaf- 
stalks, for example, in the nasturtium 

we find that the plant is held up entirely by the leaf 

stalks, which catch on to anything in their way (see 

fig. 103). 



Fig. 102. Soft twin- 
ing stem of Convol- 
vulus. 



CHAP. XTX. SPECIALISATION FOR CLIMBING 



107 




Very many plants which depend on others for support 

modify their leaves, or parts of 
leaves, to form sensitive ten- 
drils which twine quickly 
round any prop they can find, 
and thus hold up the stem (see 
fig. 104). The young tip of the 
stem continues to grow up- 
wards, the next young leaves 
unfold their soft green tendrils 
which twist round a support 
directly they feel it, and so the 
plant goes on growing higher 



Fig. 103. Nasturtium stem held 
up by the support given by the leaf- 
stalks, which cling around any suit- 
able prop. 

and higher. You can see 
the fate of a pea-plant 
which does not find 
supports, by growing 
one in a big pot all by 
itself. It will grow up- 
right at first, but it will 
soon have to creep along 
the earth and fall over 
the edge of the pot, for 
its stem is not strong 
enough to support its 
own weight. 

In vines and marrows 

We also get tendrils, but Fig. 104. Sensitive tendrils of the Pea. (t) 

they are not modified tendrilatendoffolia g eleaf ,() ordinai T leaflets 
leaves, but special branches which have become sensi- 
tive. 




io8 



SPECIALISATION FOR CLIMBING CHAP. XIX. 



In some plants the sensitive tendrils do not twine, 
but instead form little sticky suction pads at their tips 

whenever they come in con- 
tact with the support, and 
these hold the tendril very 
firmly on, as you can see in 
the ampelopsis, which grows 
right up the walls of houses. 
If you look under the thick 
covering of leaves, you will 
find these tiny padded tendrils 
clinging tightly to the wall (see 
fig. 105). This is the reason 
that the ampelopsis grows so 
well up the walls without being 
held up artificially. 

There are many other things 
you may find out about climb- 
ing plants, but you will have 
seen enough to be able to 
look for more for yourself, and to understand how it is 
that the climbing plants can reach such a great height 
so quickly. They have learnt to avoid the trouble and 
expense of building strong supporting stems for themselves, 
and by getting their support from others, they are able to 
grow quickly out into the good positions for the light which 
they could not otherwise have reached. 




Fig. 105. Ampelopsis, which 
supports itself by the little suction 
pads developed at the ends of the 
tendrils. 



CHAPTER XX. 
PARASITES 

WE call a plant or animal a Parasite when it does no 
food-building for itself, but adapts its whole structure 
to obtain and use the food made by the work of other 
plants or animals. Plant parasites generally attach 
themselves to a " Host " plant so closely that they suck 
their food from it, and sometimes remain with it till 
they have finally killed it, and so have destroyed their 
only source of food and means of life. 

Among plants, most of these degenerate creatures 
belong to the group of Fungi. The rust and smut on 
wheat, the mildew on fruit, and nearly all the thousand 
spots, blemishes, and diseases of cultivated and other 
plants, are the result of the parasitism of some members 
of the family of fungi. Plants which prey like this on 
others are without very many of the characteristics of 
true plants ; they become colourless, losing their green 
substance, and with it all power of building food for 
themselves, so that they are quite dependent on the 
host plant, without which they must ultimately die. 

Fungus parasites, of which there are many thousands, 
have become so specialized that they are quite a study 
in themselves, and we will leave them for the present 
and follow the history of a few of the higher plants which 
have taken to this mode of life. 

One of the most completely parasitic of the flowering 
plants is the dodder, which you may often find growing 
on clover. In fields of clover sometimes there are 
colonies of dodder, which live together and kill the 
clover in great patches so that it almost looks as though 



TL09 



no 



PARASITES 



CHAP. XX. 



it had been burnt. Dodder grows on other plants, such as 

gorse, as well as clover, and even 

on nettles. If you find a plant 

of dodder you will see that it 

seems to consist of nothing 

but fine, white or pinkish 

threads, twisted round and 

round the clover stems and 

hanging in festoons over them. 

Pull off these fine threads 

carefully, and you will find 

that at intervals along them 

there are little sucker-like pads 

which hold the dodder quite 

firmly on to the plant on which 

it is growing. If you cut 

through the middle of one of 

these pads and the clover-stem 

while they are still attached, 

and look at the cut with your 

magnifying-glass, you will see 

how the tissue of the dodder 



Fig. 106. Dodder plants grow- 
ing over Clover, (a) clusters of 
Dodder flowers. 

pad enters right into the 
tissue of the clover stem 
(see fig. 107). These pads act 
as suckers for the dodder and 
draw from the clover all the 
ready - formed nourishment 
that the dodder requires, so 
that it has no work to do in 
food building. It has no roots 
the suckers act as roots in 





Fig. 107. Section, A, across the 
Clover stem, with the Dodder D at- 
tached. S, suckers of the Dodder, 
entering the Clover. 



because it needs none 



getting all the water and also the manufactured food 



CHAP. XX. 



PARASITES 



in 



the plant uses ; for the same reason it requires neither 
leaves nor green chlorophyll, and its body is only a 
colourless or pinkish mass of thread-like stems and 
sucker pads. 

There is one thing, however, that the clover plant 

cannot do for the dodder, and 
that is, make its seeds. When 
the clover builds seeds, then 
they are clover seeds and will 
grow up as new clover plants. 
The dodder must build its own 
seeds if dodder plants are to 
grow from them. That is why 
we find growing out from the 
simple reduced thread of a 
stem, relatively large tufts of 
flowers (see fig. 106), which 
are very little different from 
usual flowers and which form 
seeds. The dodder belongs 
to the same family as the con- 
volvulus, and though its flow- 
ers are small, if you examine 
them with a magnifying-glass 
you will see that they are very 
much the same in structure as 
those of the convolvulus. 

When the young dodder 
plant grows out from the seed, 
it is a simple little thread with 
no leaves, and it keeps on 
growing at the tip, which it 
moves round till it feels some 
suitable host, then it quickly fastens on to it and lives 
on its food. 

This is the general history of all kinds of parasites, for 
when any living thing ceases to use its structures and 
becomes a complete parasite it loses nearly all its parts, 




Fig. 108. Young Mistletoe at- 
tached by its sucker-like roots S to 
a twig of apple A, split open. 



112 



PARASITES 



CHAP. XX. 



as there is no longer any need for them. So that 
parasites tend to sink to a lower level of development 
simply as a result of their way of living. 

A plant which is largely a parasite, but yet does a little 
work for itself, is the mistletoe (see fig. 108). Its leaves 
are greenish, but not the true healthy green of a hard- 
working plant. If you can find a bough of mistletoe 
growing on an oak or apple tree, you will see that it has 
no root in the earth, but grows out of the bough of the 
host tree. It has sucker-like roots at the base of its 
stem, which go right into the stem-tissues of the host 
and get much nourishment from them. 

In the winter, when 
the flow of food is 
very slow in the 
host, it is likely 
that the mistletoe 
does some of its own 
food building in its 
yellow-green leaves, 
which would be ex- 
posed to the full 
light, as the host's 
leaves would have 
fallen away. The 
mistletoe has soft, 
white fruits which 
are scattered by 
birds, and as they 
are very sticky, they 
hold for some time 
on to the branch 
where they are 
dropped, and there 
the seedling sprouts 
and fastens itself on to the tissues of the host, growing 
every year with its growth. 

Quite a number of plants which grow in the ground 




Fig. 109. P, parasite attached to the root R of 
a host plant H (which is the Ivy). A is the host 
root on the other side of the parasite. 



CHAP. XX. PARASITES 113 

attach themselves with suckers to the roots of other 
plants, from which they get all their ready-made food. 
Plants which do this are generally colourless or brownish 
yellow, like the broomrape, which has only whitish 
leaves which cannot do the proper work of leaves (see 
fig. 109). 

Then there are several plants which are partly parasitic, 
but which you would never guess were anything but 
ordinary plants. For example, the little eyebright with 
its green leaves, which do most of the food-building, 
is yet partly parasitic. If you very carefully get out a 
whole plant with its complete roots (this is rather diffi- 
cult to do, and you must not pull it hastily, or you will 
break the connections), you will find that there are tiny 
suckers on them which connect them with the roots of 
the plants which are growing near. So that the eye- 
bright gets some of its food ready-made from the neigh- 
bouring plants. The meadow cow-wheat does the same 
thing, and so do the lousewort and several others; 
but they are not complete parasites, for they are green 
and do a lot of work for themselves, even though they 
are not quite self-supporting, and tap the supplies of 
other plants to some extent. 

Among flowering plants, parasites are not common. 
We see in plants like the eyebright and cow-wheat, which 
do a little thieving, that the results are not very serious, 
and they are little altered by their habit. In those 
which are entirely parasitic, however, like the dodder, 
the result is the loss of nearly all the organs of the 
plant except the flowers, which have to be kept in order 
to build seeds. 



(C260) 



CHAPTER XXI. 

PLANTS WHICH EAT INSECTS 

As a rule, plants are the sufferers and are eaten by 
animals, but there are cases known in which this state 
of things is reversed ; the plants catch and devour the 
tinier animals and small insects such as flies. But, you 
may ask, how can they do that, for the insects move so 
quickly, and the plants are fastened by their roots to one 
spot. Just as a spider builds a web and then waits 
quietly beside it till the flies are caught, so the plants 
build traps which catch the unwary insects. There are 
not very many plants growing wild in England which do 
this, but there are one or two that you might be able to 
find. 

There is the sundew, which grows among bog-moss 
in wet, swampy places at the edges of lakes, or on the 
wet patches on hillsides. It is fairly common in such 

places, a little distance from 
big towns, but it does not 
like smoke, so that it will not 
live within a few miles of 
London, Manchester, or any 




big smoky town. It is a 
small plant with round, red- 
dish-coloured leaves, cover- 
ed over with little fingers or 
tentacles each with a spark- 
ling drop of sticky moisture 
at the end, so that even in 
the heat of the day when all the dew is dried up, the 
whole plant looks as though it were spangled with tiny 



Fig. no. Plant of Sundew, show- 
ing the round leaves covered with 
tentacles. 



CHAP. XXI. PLANTS WHICH EAT INSECTS 



dew-drops, 
ance which 




Fig. in. Single leaf 
of Sundew, with the 
tentacles closing over 
a fly. 



Perhaps it is this cool, sparkling appear- 
attracts the insects to it, but when once a 
fly alights on one of the leaves, its fate 
is sealed. The tentacles with their 
sticky tips bend over one by one till 
the fly is quite covered in by them and 
cannot get away. It dies, and is di- 
gested by the juices given out by the 
leaf, which are very much like the 
digestive juices of animals. 

You can watch the movement of the 
tentacles very well if you drop a minute 
piece of meat or white of egg on to the 
leaf. They will close over it one by 
one till it is quite shut in, and when the egg is all 
digested, they slowly open out again. The time ( that 
this takes depends a little on the 
health of the plant and the time of 
the year, but generally all the ten- 
tacles are bent over in a few minutes. 
The digestion takes longer, of course, 
at least several hours and often more, 
partly depending on the size and 
nature of the piece of food. The sun- 
dew leaves contain chlorophyll and do 
some of the usual work of leaves, but 
the plant gets much of its nourish- 
ment from the insects it catches. 

In the butter- 
wort there is a dif- 
ferent arrangement 
for catching its 
prey. You will 
find its little clus- 

r i j Fig. 112. Butterwort, showing the rolled leaves 

ters O I broad, which catch flies and other small insects. 

spoon - shaped, 

yellowish-green leaves growing in marshy places and 

beside streams in hilly districts. In the spring one or 




u6 



PLANTS WHICH EAT INSECTS CHAP. XXI. 



two lilac flowers on long stalks come up from the centre 
of the group of leaves. The leaves of this plant also 
act as insect traps ; they are covered with little sticky 
glands, and when an insect settles on them, the edge 
rolls over and shuts it in, keeping it there till the juices 
given out by the glands have digested all that is worth 
digesting, when the leaf unrolls again, and the remains 
of the feast are washed away by the rain. 

There is one more animal eater which you must try 
to see, which grows in the water of slow-running streams 

and in ponds. It is the bladder- 
wort, on which we find very many 
tiny bladder -like structures on 
the finely divided leaves under 
the water. The 
bladders are 
built on some- 
thing of the same 
plan as a lobster 
pot, with bristly 
hairs pointing in- 
to the entrance, 
across which 
there is a little 
flap,which makes 

it quite easy for the very minute 
animals living in such abundance 
in the water, to swim into the 
bladder opening, but extremely difficult or almost im- 
possible for them to swim out again (see fig. 114). So 
there they must finally die, and their nourishing juices 
are absorbed by little compound hairs, many of which 
are developed on the inside of the bladder. 

In the tropical countries there are many kinds of 
" pitcher plants" with wonderful soup-kettle-like pitchers 
which catch insects. You may be able to see these 
plants in a big greenhouse, and should certainly find 
them in every botanical garden. Notice how large the 





Fig. 114. A single 
bladder of the Blad- 
derwort, much en- 
larged, showing the 
pointed hairs and the 
flap at the opening. 



Fig. 113. A piece of leaf 
of a Bladderwort showing 
the bladders on the branches. 



CHAP. XXI. PLANTS WHICH EAT INSECTS 



117 



pitchers are, and that they are really modified leaves 
which have become different from the other leaves of 
the plant because of their special work. They gener- 
ally contain 
a consider- 
able quantity 
of water as 
well as the 
flies they 
have caught, 
and are really 
"stock -pots" 
which keep 
the plant 
supplied with 
nourishing, 
ready - made 
food in addi- 
tion to the 
food which 
it builds for 
itself in the 
green leaves. 

Though 
these plants 

have specialised themselves to catch and use animal 
food, still there are not very many plants that do so, and 
the old fairy tales about trees with branches which 
caught men and devoured them, as a sea-anemone 
catches and devours its food, are only fairy tales, because 
no such plants exist. 




Fig. 115. Pitcher 
penthes, which acts 
kettle." 



leaf of Ne- 
as a "soup- 



CHAPTER XXII. 

FLOWER STRUCTURES IN RELATION TO INSECTS 

THE relation between flowers and insects is one of 
mutual help and advantage, and therefore is quite 
different from that in the cases where the animals eat 
the plants or vice versa. - 

When we examined flowers in general, we found that 
the insects do a very important work in carrying the 
pollen from flower to flower, and that their structures 
are arranged to attract insects and to make it easy for 
them to get covered with the pollen of one flower and 
leave it on the next. If we look at the details in some 
of the flowers, we shall see how elaborate their structures 
may be, and how carefully they are planned to make 
sure that the bee gets the pollen on its body and carries 
it with it to the neighbouring flowers. 

In the simple circular flowers, such as roses, poppies, 
and lilies, the bee can enter 
freely from any side that it 
chooses, and it generally goes 
straight to the centre. Many of 
these simple flowers, therefore, 
have large numbers of stamens 
which stand up in a crown in the 
middle, so that the bee must 
Fig.n6. circular flower of touch and stir some of them as 
t R he S cen7re h **** si " mens m he dives in the centre for the 

honey. 

In others which are nearly circular, there is a little 
difference between the back and front of the flower, and 
the stamens are so placed that the visiting insect must 




118 



CHAP. XXII. IN RELATION TO INSECTS 



119 




Fig. 117. Slightly 
two-sided flower of 
the Foxglove, with 
the petal tube cut 
open to show the 
four stamens bend- 
ing to the front. 



touch them. For example, look into the bell of a fox- 
glove, where you will find only four stamens, but they 
are bent so that the anthers together 
form a kind of platform in the front of 
the flower, over which the bees must pass 
as they enter (see fig. 117). Frequently 
the stamens bend in this way towards 
the front of the flower, and in many 
cases the whole flower becomes quite 
definitely two-sided, with a front and 
back, and a special place for the entrance 
of the bee. 
This is the 
case with the 
violet, pea, 
monks hood, 
and many 
others (see 
fig. 118). 

When flowers have this 
form, you frequently find 
that the 
number 

of stamens is quite small, seldom 
more than ten, and often less. 

A plant of this kindi very inter- 
esting to watch is the yellow gorse. 
If you can get up and sit by a 
flowering bush from about half- 
past five to seven one sunny morn- 
ing, you will be able to learn a great 
deal about the doings of the bees 
and flowers. 

First examine a flower so that 
you know how it is arranged. At 
the back lies the big petal, or 
" standard," as in the pea ; there are two side wings, 
and in the front the two petals close together forming 




Fig. 118. Two-sided flowers: A, 
Monkshood ; B, Violet. 




Fig. 119. (a) Flower of 
the Gorse after the insect's 
visit, showing the inner 
parts exposed ; (6) young 
flower nearly ready to be 
visited. 



120 FLOWER STRUCTURES CHAP. XXII. 

the " keel." The two-sidedness of this flower is very 
well marked. Inside the keel you will find ten stamens, 
all joined to form a tube except the back one, which is 
free, and inside them lies the carpel with its curved 
style. When the stamens are ripe they are so fitted 
that they lie inside the keel of the petals in a bent form, 
and when they are pressed from above they fly out 
with a little explosion and scatter the pollen dust about. 
Now watch a bee alighting on the flowers ; he presses 
the two front petals with his legs to open them to get 
at the honey, and the stamen explosion covers him all 
over with pollen. Then he goes to the other flowers, 
but perhaps the next one he visits has already exploded 
and the ripe stigma is exposed in the front of the flower, 
and as he settles he touches it with his furry body all 
covered with pollen, and leaves some on it. If you 
watch the bees doing this yourself, you will find out 
a number of things which I have not told you, while 
you may notice how some of the bees are lazy and enter 
the wrong side of the flower, others are stupid and go 
to flowers which have already been visited several 
times, and therefore are of no use, while other bees 
which come late may open up buds which were not 
ready for them and steal the honey before the stamens 

are ripe enough to 

A. T5. smother them with 

pollen. I have watch- 
ed them opening buds 
which were still so 
tightly closed that it 
took them all their 

Fig. 120. The two kinds of Primrose flowers, strength to get in. 

A, with long style and stamens low in the petal Rnf W p rrmct not <^tnn 

tube ; B, short style, with stamens at the mouth ^ Ul W mUSl 

of the petal tube. too long With One 

flower, for almost 

every flower has some special arrangement of its own, 
and all are worth study. 

The primroses and cowslips are interesting, as they 




CHAP. XXII. IN RELATION TO INSECTS 



121 




Jt. 



have two kinds of flowers. If you gather a bunch of 
primroses and look into them you will find that in some 
you can see the little central green ball of the stigma, and 

in others at 
the top of 
the tube are 
the five 
small an- 
thers. These 
two kinds 
of flowers 
make an ar- 
rangement 

Fig. 121. A, Flowerhead of the Daisy ; (6) a single little which en- 
flower from the side with big petals fused together; (c) a c .,_- i.L_f 
single little flower from the middle with very small petals. 

the pollen 

from the one kind of flower reaches the stigma of the 
other. A big fly like the wasp-fly, and several others, 
visit these flowers most frequently, and carry the pollen 
from flower A (see fig. 1 20) to 
the stigma of B, and the pol- 
len of B to the stigma of A. 
As we noticed before, the 
chief duty of the petals is to 
act as flags to attract the 
visiting insects by their 
bright colours. Now we 
find that some flowers club 
together, and grow cluster- 
ing closely on one head, so 
that it is sufficient for a few 
of them to have the flag 
petals which attract the in- 
sect to the group, as it goes 

from one to the other when once it is there. When a few 
of the flowers do this, the rest can economise in petals and 
have quite small ones, and yet all the same they have a 
good chance of insect visits. Such an arrangement as 




Fig. 122. Flowerhead of the Corn- 
flower ; (a) a single flower from the 
side with big petals. 



122 FLOWER STRUCTURES CHAP. XXII. 

this is found in the daisy (see fig. 121). A single daisy 
is not one flower, but a whole bunch of flowers, in which 
some of the outer flowers of the bunch (see fig. 121 (b)) 
form big petals, while all the inner ones (fig. 121 (c) ) 
are quite small and inconspicuous, and by themselves 
would hardly attract any visitors. Just the same thing 
happens in the cornflower, sunflower, and very many 
members of the daisy family. The big outer petals 
attract the insect, and once on the head of flowers it 
walks about over them, and they all get the benefit. 

In such cases we get a division of labour among the 
flowers of a head, and this represents what is perhaps the 
highest state of development that flowers have reached. 



PART IV. 

THE FIVE GREAT CLASSES OF PLANTS 

INTRODUCTORY 

IF you go out into the garden, or fields and woods in 
summer, and look around you at the plants, you will 
find that nearly all of them are flowering, or have flower- 
buds, or have the proof of having had flowers in the 
shape of fruits and seeds. Even among the few which 
do not show any of these things, many will probably 
be plants which you know to be the same as others of 
their kind which you have seen flowering. 

Generally flowers (such as roses and daisies) are easy to 
see, but in some plants they are less showy, as in the oak, 
for example, where the little green tails or catkins which 
come out early in the spring are the flowers. On the 
whole, however, if you look carefully, you will have no 
difficulty in seeing proof that nearly all of the conspicu- 
ous plants of our gardens and woods bear flowers. 

All the same, there are very many other plants, some 
of them quite easy to see, and others very small and in- 
clined to hide, which do not have flowers at all, and 
which are so different from the flowering plants that 
even before you have studied them, you instinctively 
separate them. The seaweeds or mosses, for example, 
are at once recognized by any one as being of a different 
family from roses and lilies. 

When you have studied all the plants carefully, you 
will see how true is this instinctive separation of the 
chief families, and how nature seems to have made five 
principal big families, so that both scientists and quite 
unlearned people see more or less clearly the limits she 
has set to each. 



123 



i2 4 INTRODUCTORY 



The family which is most highly advanced is that of 
the flowering plants, but the others, too, are well worth 
study, and we will now notice some of the points about 
their structure which are characteristic of each of the 
families. 



CHAPTER XXIII. 
FLOWERING PLANTS 

All the plants 'which have flowers are put into one 

big family, about which you already know a good deal, 
because nearly all the plants we have studied up to the 
present have been plants which have flowers. Let us 
now go systematically over the chief points about their 
structure, so that we may have a clear idea of their 
characters, and be able to compare other families with 
them. 

1 . We find that the plant body is clearly marked out 
into rooty stem, leaves, and flowers. The stem may be 
green and delicate, or it may be thick and strong like an 
oak tree, and on the stem or its branches we find the 
leaves. 

2. The stem and root have definite strands of "water- 
pipe " cells, and very often the stems have many rings 
of wood, one of which is added every year. 

3. The leaves are very various in the different plants, 
but they are generally thin and big, though they are 
seldom much more compound than those of the sensitive 
plant. 

4. The flowers are easily recognized, as a rule, and 
consist of a number of parts, some of which are often 
brilliantly coloured. The stamens and carpels are 
generally in the same flower. 

5. The seeds are always enclosed within the carpels, 
and have generally two seed-coats. 

6. Within the seed are always either two cotyledons, as 
in the bean, or one cotyledon, as in the grasses. Thus 
when the seedling grows out of the seed it may have 
two first leaves or one only. 



125 



126 FLOWERING PLANTS CHAP. XXIII. 

These are the chief characters of the whole big family 
of the flowering plants, but this big family is separated 
into two smaller groups according to the number of coty- 
ledons in the seed. Those that have two form the group 
of Di cotyledons, those with one the group of Monocoty- 
ledons. This may not seem a very important point to 
form the ground for separating plants with flowers so 
alike as tulips and roses, but we find that, as well as the 
number of cotyledons, many other differences distinguish 
the two groups when we separate them in this way. 
For example, the Dicotyledons have the veins of their 
leaves so arranged as to form a network, as in the lime, 
while the Monocotyledons have them parallel, as we 
noticed in the grasses and lilies. 

We also find that it is only in the Dicotyledons that 
the plants have rings of wood in their stems, as is the 
case in the lime, oak, and many others. 

In the numbers of the parts of the flower, we also 
find differences between the two groups ; for example, 
the Dicotyledons have generally two, four or five, or a 
multiple of these numbers such as ten, as we see in the 
poppy, primrose, rose, and many others ; while the 
Monocotyledons have the parts of their flowers in three 
or multiples of three, as in the lily, tulip, and daffodil. 

These differences between the Monocotyledons and 
Dicotyledons, however, are not nearly so important as 
their likenesses, for they agree in the main points (i) to 
(6), and therefore belong equally to the great family of 
the flowering plants, which is the most important family 
now living. 



CHAPTER XXIV. 
THE PINE-TREE FAMILY 

SINCE trees such as the oak, beech, and lime all belong to 
the family of flowering plants, you may be surprised to 
find that the pine-trees are separated from them. Yet 
all the trees like pines, Christinas trees, larches, and 
many others, form a family of their own. You will 
see why this is, if you look at a pine-tree carefully, and 
compare its characters with those we saw in the flower- 
ing family. In the first points the two families are alike. 

1. We find that the pine-tree body is clearly marked 
out into rooty stem, leaves, and cones. 

2. Also that the stem and root have definite strands 
of " water-pipe " cells, and that the stem has rings of 
wood, one of which is added every year. 

3. The leaves vary a little in the different members of 
the family, but the commonest kind of leaf is the fine 
sharp " needle " leaf of the ordinary pine (see fig. 53). In 
almost all cases the leaves remain on the tree for more 
than a year ; they are evergreens (it is only the larch 
among the English-growing members of the pine-tree 
family which has new leaves every year), and the leaves 
are simple and strong, and well protected. 

4. There are no l< flowers" but the two kinds of cones 
which take their place are easily recognised. The two 
kinds of cone generally grow on different branches of 
the tree, the small ones only live a short time and scatter 
the pollen, and the larger ones often remain two or three 
years on the tree, and form the seeds. The wind scatters 
the pollen ; you will remember in the spring-time 
before the leaves are out, how the " sulphur rain " 



128 



THE PINE-TREE FAMILY CHAP. XXIV. 



showers down from the pine-trees; this is the yellow 

pollen, which is blown in 
clouds on to the seed-bear- 
ing cones. There are mil- 
lions of pollen grains scat- 
tered in this way, and but 
few of them ever reach a 
cone. You will remember 
that many of the flowering 
plants could afford to make 
small quantities of pollen, as 
they had special carriers in 
the insects to take it from 
flower to flower. 

Besides the pollen cones, 
you should find two sizes 
of seed-cones on the tree : 
some quite small, and green 
or pink, and some large ones 
which are brown and ripe. 
It will be easier to see their 
structure at first in the big 

ones ; they consist of a number of brown scales packed 




Fig. 123. A branch of Pine with a 
small young seed-bearing cone, and 
a large ripening one. 




IB 

Fig. 124. Larch. A and B, young scales, showing (i) inner seed-bearing 
scale, and (o) outer protective one. A, side view ; B, front view ; C and D, old 
scales, C from the side, D from the front, showing how the inner scale increases 
more rapidly than the outer. 

neatly one over another. If you pull these apart you will 
see that each of them bears two seeds on its upper side. 



CHAP. XXIV. THE PINE-TREE FAMILY 



129 




Fig. 125. 
Winged seed 
of the Pine. 



5. The seeds are always seen to be lying 
quite openly on the upper side of the scales, 
and are not covered in by closed carpels as 
they are in the flowering plants. Each of 
the scales (which bears its two seeds) corre- 
sponds in a way to the carpel in a flower, but 
there is an important difference in the fact 
that it leaves the seeds open. In old pine 
cones there seems to be only one scale to 
each pair of seeds, but there is really a second smaller 

one outside 
it which is 
sometimes 
quite diffi- 
cult to see. 
It shows 
betterin the 
larch,where 
the outside one is 
much the bigger of 
the two in the young 
cones, and gradually 
gets left behind, as 
the inner scale grows 
very fast(s fig. 124). 
Notice, too, how the 
ripe seeds have one- 
sided wings, which 
split off from the 
inner scale, as you 
can see if the cone 
is not too ripe. This 
wing is on the seed 
itself, not on a fruit, 
as is often the case 
among the flower- 
ing plants. Thewin^ 

Fig, 126. Stages in the growth of Pine seed- i i ji 11 n 

lings ; (c) cotyledons. helps the SCCd to fly, 

( C 260 ) K 




130 THE PINE-TREE FAMILY CHAP. XXIV. 



and in the late autumn (in many cases two years after it 
began to grow, for some pines grow very slowly) it is 
scattered with its brothers. If you are ever near pine 
trees when there has been snow, you may see it sprinkled 
with these winged brown seeds. 

6. You may never have seen a baby pine tree. If 
not, you must get some seeds and grow them. They 
grow very slowly at first, and may take six weeks to 
show above ground even in summer ; but they are well 
worth waiting for. Notice how they come up (see fig. 
126), and that at the beginning of their growth, as they 
come out from the seed, they have seven or even as 
many as twelve first leaves, and these leaves are really 
the cotyledons, as you may see by cutting a seed across. 
So that instead of the one or two cotyledons of the 
flowering family, we find in the pine family that there are 
manv cotyledons, and that their number may vary from 
five to ten or more. 

If you go back over these points, you will see that we 
have found a large number of differences between the 
flowering plants and the pines. Of these, the most im- 
portant are the points (5) and (6), which alone would be 
enough to make us place the pines and flowering plants 
in separate families, though point (4) is also very im- 
portant. We find, however, that the pines are more like 
the flowering plants than are any of the other families, 
so that they are the nearest relatives the flowering plants 
have, even though they are rather far-away ones. 



PLATE III. 




TREE FERNS, SHOWING THEIR TALL THICK TRUNKS 

AND LARGE LEAVES, WITH SMALLER FERNS GROWING 

BENEATH THEM 



CHAPTER XXV. 

FERXS AND THEIR RELATIVES 

Perhaps there is no family of plants so easy to 
recognise as the ferns. It is nearly always a simple 
matter to know whether or not a plant is a fern, for 
although there are hundreds of different kinds, they all 
have the family characters plainly marked. 

We have not very many ferns growing commonly in 
England, for they generally require a moister air than 
is usual in this country. By far the commonest is the 
bracken, which grows in all parts of the country, and 
sometimes in very large masses (see Plate I.). Some 
people separate the bracken fern from the others, and 
speak of "bracken" and "true ferns," but this is not at 
all correct, for the bracken is just as much a true fern 
as the others, only as it is so much commoner, people 
are apt to value it less. 

In some countries, particularly in the tropics, there 
are (as well as ferns like ours) very large ferns with tall, 
strong, upright stems, and crowns of large spreading 
leaves. Such ferns you can see in Plate III., and they 
are called tree ferns. Notice how thick the stem is, and 
how large the leaves are compared with it, while the 
trunk seems to be all rough and hairy, which is due to 
the jagged bases of the old leaves which have fallen 
away. Yet even the tree ferns are easily recognised as 
belonging to the fern family. 

Let us examine ferns in order to find out what are the 
points about them which are specially characteristic for 
their family, and which help us to separate them from 
the other plants. 



133 



FERNS AND THEIR RELATIVES CHAP. XXV. 



1. We find that the fern body is clearly marked out 
into roots, stem, and leaves, but there appear to be neither 
flowers nor cones. 

2. The stem and roots have definite " water-pipe " 
cells, as you can see if you examine a thin slice with 
your magnifying-glass, but there are never rings of wood 
formed year by year, as in the higher families. The 
stems are frequently short and stumpy, and often run 
underground. They are usually covered by the rough 
leaf-bases of old leaves and by dry scales. 

3. The leaves are generally few in number, often only 

three or four, but they are highly com- 
pound, and are split up into very many 
side leaflets. They are generally thin 
and delicate. When they are young they 
are rolled up in the bud in a close coil 
(see fig. 127), and as they unfold they 
bend back. This way of coiling up is 
quite a special character of ferns. The 
buds are generally covered with flaky, 
shining scales, which stick all over the 
young leaf-stalk. 

4. Yon have never seen a fern with 
flowers or seeds, yet there are always 
plenty of new ferns every year. How 
are the young ones formed ? For a long 
time botanists did not know, so that 
people thought there was some magic about it, but now 
we know the whole story, and it is a very interesting 
one. 

5. There are no seeds, and 

6. Therefore there are no seedlings to have cotyledons. 
You must have noticed little dark brown spots on the 

backs of some fern-leaves. It is in them that you must 
look for the beginning of the new fern plants. The 
little patches are at first hidden by green coverings, 
but when they are ripe these bend back, and expose 
the little brown clusters within. If vou look at one of 




Fig. 127. Young 
leaf of a Fern rolled 
in a close coil. 



CHAP. XXV. FERNS AND THEIR RELATIVES 



135 




Fig. 128. A small piece 
of Fern leaf showing the 
patches of spore-cases on 
the under side. 



these ripe patches with a magnifying-glass, you may be 

able to see a number of little roundish boxes on stalks. 

Each of these contains a number of tiny " spores " 

(which are single cells with the 

power to grow), and when the 

spore-cases are ripe they open and 

shoot out the spores, as you may 

perhaps see if you look closely at 

a ripe patch when it is taken into 

warm, dry air. 

These brown patches are not at 

all like flowers, but in some way 

they do the work of flowers, for 

they give rise to cells which can carry on the life of the 

fern to a second generation. The way in which they 

do it, however, is totally different from that of the seed, 

and is quite the most special character of the ferns and 

their relatives. 

The spores grow slowly when they come on to moist 

earth, but as their develop- 
ment takes a long time, you 
had better get some from a 
gardener which have already 
grown. As the spore grows, 
the one cell composing it di- 
_ vides and divides again, until 

^C*^? there is formed a little filmy 
^j heart-shaped green structure 
called a prothallium (see fig. 
129), which is not in the least 
like a fern plant, for it is not 
more than a quarter of an inch 
across. It has no stem or 
leaves, and is only a thin layer 

of green cells, with a few root-hairs on the under side. 

Two of the cells formed on this little structure then 

unite and begin to grow while still attached to it, and 

finally they grow into the form of a very small, simple 




Fig. 129. A Prothallium (jf>), 
with a young Fern (/) growing 
out from it. (Magnified). 



136 FERNS AND THEIR RELATIVES CHAP. XXV. 

fern plant (see fig, 129). So that between the old fern 
plant and the little fern " sporeling " (for we cannot call 
it a seedling) we find a whole new structure, the pro- 
thallium, which is quite different from the usual fern 
plant. This curious alternation of fern, prothallium, 
fern, and then again prothallium, is what we call 
"alternation of generations," and is very characteristic* 
indeed of the fern tribe. 

Some ferns take a short cut, and bear little ones 
directly on their leaves without any prothallium. You 
see this in the " Hundreds and Thousands " fern, where 
the old plant is sometimes covered over with little ones, 
which will grow if they are taken off and planted care- 
fully. 

Sometimes people are deceived by what is called the 
"flowering fern," and expect that it will have flowers. 
In this fern we find that all the spore-cases grow 
together on a special leaf, which is so covered by them 
that it looks quite different from a usual one, and is 
called the flower, though it is not one. In all other 
ways the story of the spore building and growth is like 
that of usual ferns. 

In our study of ferns, you see that they have many 
characters which are exceedingly different from either 
the flowering plants or pine-trees. In fact, they are so 
different that we require to add some new points to our 
list of characters for family divisions, which are : 

7. Instead of flowers there are little spore-cases, which 
contain a number of simple one-celled spores. These are 
generally found on leaves which are otherwise like the 
rest of the leaves of the plant. 

8. Each spore grows out to form a small green structure, 
which differs from the parent, and which we call the pro- 
thallium. 

9. The new fern-plant grows at first attached to the 
prothallium, but soon grows out beyond it, and is quite 
independent. 

What we call u ferns " are not the only plants which 



CHAP. XXV. FERNS AND THEIR RELATIVES 137 

belong to this big family, for the club-mosses and also 
the horsetails have almost the same arrangement for 
their building of new plants. Our character-points (7) 
(8) and (9) apply to them, even though the rest of their 
structures appear to be so different from the ferns. 
They are, therefore, put in the same big family with the 
ferns, though they have smaller classes for themselves 
apart from the true ferns. 

Neither the ferns nor their near relatives are very im- 
portant in the vegetation of to-day, but very long ago 
they were among the chief plants in the world, and 
grew to be as big as forest trees. Even then, however, 
they had almost the same way of forming spores that 
they have to-day, a fact which still marks them out as a 
family different from all the other families of plants. 



CHAPTER XXVI. 



MOSSES AND THEIR RELATIVES 

Mosses form another big family, the members of 
which are generally easy to recognise, even when you 
know little about them, because they all have a very 
strong family likeness. If you look for mosses in a shady 

wood, or on stones 
and tree stumps 
near a waterfall, you 
will often find large 
numbers of them 
growing together, 
sometimes forming 
sheets of soft green, 
covering the stones 
and earth and tree 
stumps. These 
luxuriant mosses 
grow, as a rule, in 
moist and shady 
places, but there 
are others which 
gro\v on dry walls 
or between the 
cobbles of little- 
used paths, and 
generally form brilliant green patches of tiny plants, like 
masses of velvet. If you pick out a separate plant from 
among these and look at it through a magnifying-glass, 
you will see that it is very like the bigger ones of the 
wood. 




Fig. 130. A clump of Mosses, showing the 
flower-like appearance of the tips of their branches. 



CHAP. XXVI. MOSSES AND THEIR RELATIVES 



I 39 



For our study it is perhaps better to choose one of 
the bigger ones, because all its parts show so clearly. 

T. If you take a single plant, you will find that it 

appears to be marked 
out into root, stem, and 
leaves, though all these 
parts are small and 
simple. 

2. The stem is deli- 
cate, and you will not be 
able to see any " water- 
pipe " cells when you 
examine it with your 
magnifying-glass. 

3. The leaves are al- 
ways very simple and 
small, generally narrow, 
pointed, and clustered 
thickly round the stem 
with no special leaf 
stalks. 

4. At the ends of the 
stems, you will often 
find little structures, 
sometimes rather pink 
in colour, which look 
something like flowers 
(see fig. 130), but they 
are really quite different 
in their nature from true 
flowers. 

5 and 6. There are 
no seeds and no seed- 
lings. 

7. At the top of some of those plants which seem to 
have flowers you will find later that a long slender stalk 
grows out with a little capsule or box at the end of it 
(see fig. 131 (b) )- This single box or capsule really 




Fig. 131. (a) The part of the Moss corre- 
sponding to the prothallium ; (b) with the 
spore-capsule attached ; (c) enlarged capsule, 
showing the covering: (d) naked capsule, 
showing the lid which falls off at (/). 



140 MOSSES AND THEIR RELATIVES CHAP. XXVI. 

corresponds to the numbers of small spore-cases on the 
backs of fern-leaves, for it is in this capsule that we find 
the spores, which are simple and single-celled like those 
of the fern. 

8. When these spores grow, however, they do not 
form a prothallium as they do in the ferns, but they 
grow out into the leafy moss-plant. 

It is very difficult really to see how this can be the 
case, unless you study mosses very carefully with a 
microscope, but all the same it is true that the leafy 
moss-plant corresponds to the prothallium of the fern. 

9. On the leafy moss-plant you find the simple stalk 
and capsule which gives rise to the spores ; this spore 
forming part of the plant always remains attached to 
the leafy plant, so that we find the two portions of the 
plant in contact all their lives, and not separated as they 
are in the fern. 

The only other plants which are built on anything like 
this plan are the liverworts, though you might hardly 

believe it, because most of 
them are not marked out into 
leaf and stem at all, but are 
only flat, creeping, green struc- 
tures, which do not look in the 
least like the mosses. It is 
true that they are not very 

Fig. 132. A piece of Liverwort, near relatives, but because 

showing the flat, creeping body, they have spore-cases rather 

r e ave d s. vided int r 0t ' Stem ' and like those of the mosses in some 

very important ways, the scien- 
tists have put them together in the big moss family. 
The true mosses have a special smaller family to them- 
selves within this, a family which is quite easy for you 
to recognise when you go out on your rambles into the 
woods. 




CHAPTER XXVII. 

AND FUNGI 



The last big family of plants is that containing 
the simplest plants of all. They are often very 
small and apparently unimportant, sometimes so small 
that we cannot study them at all without magnifying 
them very much with the microscope. In other cases 
they are quite large and easy to see ; for example, the 
big red and brown seaweeds, and the many toadstools 
in the autumn woods. Sometimes they may even be 
very huge indeed, as are some of the seaweeds which 
grow in tropical seas. All the same, though we examine 
one which is as big as can be, it is really more simple 
in its detail than the mosses. 

In very many of the a I gee and fungi, the whole plant 
body consists only of one single cell. When this is the 
case, the plant lives floating or swimming about in water, 
or in very damp places. In rain-water which has stood 
for a long time you may find numbers of these tiny 
algae. If you put some of the water in a glass tube and 
hold it against the light you may just see them, with a 
magnifying-glass, as specks of green, often swimming 
actively about. 

The fine green " scum " which floats on many ponds 
and slow-moving streams consists of masses of these 
simple plants, in this case generally of forms in which 
the single cells keep attached together in long rows or 
chains, forming hair-like plants. Colourless plants of 
this kind are the fungi, which are often built on the 
same plan as the hair-like green algae, only they do no 
food-building work for themselves, but live as parasites 



142 



AND FUNGI 



CHAP. XXVII. 



on other things. This is the case in many moulds and 
the plants which form potato-disease, and, in fact, the 
greatest number of plant-diseases are caused by such 
simple parasites. 

All these plants are very small and simple, and as you 
can see at once, are not at all to be compared even with 
the mosses, but there are others which seem to be more 
complicated, as are the big seaweeds and the toadstools. 
Let us see how it is they are put in the same family 

as the simplest plants 
of all. 

You can see, even 
with your magnifying- 
glass, that they have 
no special " water- 
pipes " in what you 
may call their "stem," 
(for want of a better 
name), but that their 
whole body is built 
up of numbers of soft 
cells all very much 
alike, which twine in 
and out, and build a 
kind of soft weft ; they 
have no really marked 
out stem and leaves 
Look at a toadstool, for example, there is just a stalk 
and a cap spreading out above ground, while under the 
ground there are many twining thread-like strands (see 

fig- 133)- 

Even in the seaweeds, which may seem to have 

stems, you will find that such is not really the case. They 
have generally a flat body, which is thin at the edges, 
with a stronger mid-rib, and the flat edges get worn 
away in the older parts of the plant, and so leave the 
mid-rib looking like a stem, though it is not so really 
(see fig. 134)- 




Fig. 133. A Toadstool, showing the " cap " 
and " stalk." Under the cap are the radiating 
gills, on which the spores are formed. Thread- 
like strands under the soil. 



CHAP. XXVII. 



ALGJE AND FUNGI 



When we come to look for flowers or even spore 

capsules, we see still more 
clearly how simple these 
plants are; they have 
not nearly such a compli- 
cated history as the moss. 
For example, in the toad- 
stools we find that there 
are many spores formed 
directly on its lower sur- 
face, on the a gills," and 
these grow out to form new 
toadstool plants. You can 
see the spores if you cut off 




Fig. 134. A Seaweed, showing the 
branched body, which is not divided 
into stem and leaves. 

a toadstool or mushroom head 
which looks full grown and is 
quite expanded, and then lay 
it on a sheet of gummed paper 
over-night, with the gills down- 
wards, and another beside it 
with the gills up. Next day you 
will find that the paper under 
the one where the gills were 
downwards is covered with 
radiating lines of spores, just 
as they fell from the gills, 
and repeating their pattern. 

The seaweeds have the most complicated way of 




Fi g- 135- Part of a Bladder- 
wrack, showing the floats {/) and 
special swollen tips (s). 



144 ALGsE AND FUNGI CHAP. XXVII 

forming spores of any of this family. There are special 
little swellings at the ends of the plant, as in the 
ordinary bladder-wrack, for example (fig. 135 (s)), and in 
these are formed the cells which will give rise to new 
plants. The other simple bladders (fig. 135 (/")) are 
only full of air, and act as floats to keep the plant up in 
the water. 

In this the simplest family of all, we find more 
variety in the appearance of its members than in any of 
the others, so that it may seem to be rather difficult to 
recognise the plants which belong to it. Perhaps the 
easiest way of settling this, is to see if the plant fits intc 
any of the other families, and if it never has flowers nor 
cones, neither fern spore-capsules nor the big spore- 
capsules of the moss family, then you are fairly safe in 
classing it with the simplest plants. 

Very many of the plants of this family are found 
living in water, which is perhaps one of the reasons that 
they can afford to be so simple, because the water pro- 
tects them from many of the dangers land-plants have 
to prepare against, such as wind, drought, or too much 
sunshine. This is the simplest family of real, undoubted 
plants ; but there is one class still simpler, and that is 
the family of bacteria, about which you must have heard 
much, as many of them cause our diseases, though 
others do much valuable work for us. All the same, we 
will leave these little creatures alone, and content our- 
selves with the five great families of plants which we 
can see with our own eyes. 



( C 260 ) 



PLATE IV. 




PART V. 

PLANTS IN THEIR HOMES 

CHAPTER XXVIII. 
HEDGES AND DITCHES 

WE do not sec plants growing under quite natural con 
ditions in the hedges and ditches, because they are put 
there by man in the first instance, and are continually 
kept in order by him. All the same, the hedgerows, 
which are so common in England, deserve a little study. 
They are within the reach of every one, and there we 
may often find many wild plants growing sheltered by 
the actual hedge. 

The principal plant is, naturally, the one which forms 
the hedge, and this is very commonly the hawthorn ; 
but, growing under it, and over it, and on the banks on 
either side, there are many others which are generally 
quite self-planted and truly wild. Of the bigger ones, 
the white clematis or Travellers' Joy is very common in 
the south of England, and grows climbing all over the 
hedge, and often covering it with its white flow r ers. 
We noticed this plant among those which are special 
climbers (p. 105), and we can often see very well on the 
hedges how it climbs over tree and shrub, and supports 
itself on them. 

A smaller plant, of somewhat similar habit, is the 
goosefoot. This has long, weak stems, which grow up 
amidst the other vegetation and so support themselves, 
while its leaves are arranged in whorls round the stem, 
and are narrow and rough, and help to keep the plant 
from slipping down. Notice also its fruits, how rough 
they are, and how they cling to everything. They are 
beautifully adapted to catch on to every passer-by, 



147 



148 



HEDGES AND DITCHES CHAP. XXVIII. 



whether man or animal, and so to get carried to a dis- 
tance where the seeds may grow. 

A character of the ordinary plants growing in the hedges 
is the tendency they often have to form very long, straggly 
stems, which are too fine and weak to support them- 
selves, but which are quite strong enough to grow up 

through the hedge and 
bear leaves, as they are 
partly held up by the 
other vegetation. You 
may frequently find plants 
which are usually only a 
foot or so high, and able to 
support themselves very 
well, growing up through 
the hedge to a height of 
two or three feet, and hav- 
ing thin, limp stems with 
long spaces between the 
leaves (see fig. 136). These 
plants have some of the 
characters both of those 
grown in the dark and of 
climbing plants, because 
the thick-set hedge keeps 
off the light from the low- 
growing parts, so making 
them straggly, and at the 
same time gives them the 
support they need if they 
grow rapidly out into the light, and do not build strong 
stems. Very often you may find plants of the same 
species as those that grow so tall in the hedge, growing 
in the shorter turf away from it, and there only reaching 
their usual height. 

This shows us not only that different species are 
specialised to grow under different conditions, but that 
even two individual plants of the same species may be 




Fig. 136. Two Toadflax plants grow- 
ing near together : A, on the bank by a 
hedge ; B, among the plants of the actual 
hedge. 



CHAP.XXVUI. HEDGES AND DITCHES 



149 



growing within a few feet of each other, and yet have 
quite a different appearance owing to the influence of 
their immediate surroundings. There are many such 
cases to be seen in the hedgerows. 

If the hedge runs from east to west, it will cast a 
shadow over the side lying to the north. Notice how 
different is tJie general appearance of the plants on the 
bleak side from that of tJiose on the south. You may also 
find that some species which grow on the south side do 
not grow on the north at all, or only in far smaller 

? numbers. It is quite 
fSfe worth w r hile making out 
ftfj lists of all the plants you 
can find on one side and 
the other of the hedge if 
it is a big, w T ell-established 
one, and comparing the 
numbers and condition of 
the two sets of plants. 

As we noticed before, 
hedges are not entirely 
natural, and as man there- 
fore forms a patt of ihe 
plants' environment, it is 
quite interesting to see how 
they respond to his influ- 
ence. For example, we 
may study the effect of 
his trimming the hedge. 
In a hedge which had 
been left for some time to 
itself, the plants would 
have long, thin stems, bare 
at the base, where no 
leaves would develop, as 
they would be cut off from 
plants. Then comes the 





Fig. 137. A, Dead Nettle which has 
grown up through the hedge. B, the 
same after being cut back with all the 
others. Side branches have begun to 
sprout now that it is well lighted and 
the top has been cut off. 



the 



light 



by all the other 



hedger and ditcher," and cuts them all back, leaving 



150 HEDGES AND DITCHES CHAP. XXVIII. 

often only a few inches of nearly leafless stem. What 
is the result ? Soon on these bare stumps leaves begin 
to sprout now that the light can get at them and the 
top is cut off, and many short side-branches come out, 
also bearing leaves, so that where before were only long, 
bare stems carrying the top tufts of leaves out to the 
light, we now have short, thickly clustered plants of 
bushy appearance (see fig. 137). Soon, however, the 
race for light begins again, and the plants grow taller 
in their attempt to overtop each other. Notice also 
how the hawthorn (or whatever woody plant it may be 
which makes the hedge) responds when its leafy shoots 
are cut away. Many hidden and sleeping buds in the 
brown woody stem now get their chance and wake to 
active life. It is this continual cutting back which 
makes the hedge so thick with many short branches. 

/// the ditches, which often run alongside of hedges, 
we find quite a different set of plants. The ditches are 
generally cut out to a lower level than the surrounding 
bank, and so they often contain water while the rest is 
dry. In such watery ditches the plants which you will 
find depend a good deal on the quantity of water in the 
ditch, and whether it is always there or not. If it is 
really a wet ditch, you may get many of the inhabitants 
of the lakes, or if it is a dry ditch where but little 
moisture collects, you will get only rushes and rank 
grass. An interesting kind of ditch to watch is one 
which is well supplied with water nearly all the year 
round, but may dry up during the height of summer. 
In such a position as this you are nearly sure to find 
many pond-dwellers, such as water-cress, duckweed, 
water parsnip, water buttercups, bulrushes, reeds, and 
many others, which will vary with the locality. These 
plants generally choose a spot where there is a per- 
manent supply of water, but plants cannot foresee 
the unexpected draining of the ditch, or a summer 
drought, and they are sometimes left through these 
causes to grow on bare mud. When this happens, 



CHAP. XXVIII. HEDGES AND DITCHES 



notice how they behave ; those 
which were already rooted in the 
mud may continue to flourish for 
some time, while those which 
were floating may be able to root 
themselves and tide over a short 
danger. If the water is perma- 
nently drained off, however, they 
gradually have to give in ; they 
seem to draw themselves together 
and the long, luxuriant branches 
die off, on- 
ly the short 
shoots re- 
maining, 
which are 
not so ex- 
travagant 
with wa- 
ter. The 
duckweeds, 
which you 
know very 
well as 
little float- 
ing green 

leaves, have long, thread-like roots 
hanging from them unattached to 
the soil. When the water goes, they 
first root themselves in the soil with 
these water-roots, but if the drought 

t I /fiHjf | rnS^m the plant hides in the mud, where 

li I &imr J mt Jm ^ can rema * n * or a l n S time \vait- 
Eri IBW^^J mil ! ing for the return of the water. 

In the ditches you will prob- 
ably find a number of green, 
thread-like algae ; these may also remain on the mud for 




Fig. 139. Duckweed, with 
simple leaves and long roots 
hanging in the water. 



Fig. 138. Bulrushes grow- 
ing in a wet dilch. 



152 HEDGES AND DITCHES CHAP. XXVIII 

some time when they are dried up, and in their case 
some of the cells at such times get a specially thick coat, 
and remain living for long. Then, if the water returns, 
it is again the home of these algae, which rapidly grow 
out from their protected cells. 

So that you see, even if you had no plants but those 
in the hedges and ditches to study in their homes, yet 
you could manage to find many examples of living plants 
which are trying to fit themselves to their ever-changing 
surroundings. Those that cannot succeed must die 
away in that spot, and confine themselves to some other 
place where the struggle is not too hard for them. All 
the plants which we find anywhere living together are, 
therefore, those which are suited to the conditions in 
that place, and all such plants growing together in this 
way form what is called a " plant association." 



CHAPTER XXIX. 



MOORLAND 



THE word " moorland " brings at once to the mind's 
eye great stretches of land which the farmer has left 
practically untouched. It is not like a woodland, for 
the plants are all so short that they do not shut out the 
view ; hence on the moors there is a sense of space, and 




Fig. 140. A moorland stream. Notice the low growth of all the plants. 

one can see all around the hillsides and plateaux clothed, 
though their form is not hidden, by their covering of 
plants. Let us see what are the characters of the plants 
which grow so lowly, and yet so thickly on these expanses 
of uncultivated ground. Almost the first which rises to 



J 53 



154 MOORLAND CHAP. XXIX. 

one's mind is the heather, with its short, bent stem and 
many wiry branches. If you try to pull it up you will 
find that the roots are long and fine, but strong, and 
that they grow for great distances into the soil, so that 
it is very difficult to get the plant out. The leaves are 
small and tough, and the lower ones on the stems gener- 
ally have their edges half rolled in, while the leaves on 
the ends of the branches which stand further out in the 
air are often so much rolled as to be almost entirely 
closed. Some of the heather-plants seem to be covered 
over with short hairs like soft down, while others have 
shiny strong leaves. In fact, the heather has many of 
the characters of plants which have to protect them- 
selves from drought. 

Look at the others growing with the heather ; there 
is the heath, which is so like it that almost the same 
description applies to it. Then there is the cranberry, 
which lies close to the ground, and is somewhat pro- 
tected by the other plants, and has more delicate stems, 
and larger, flatter leaves, which are also rolled in at the 
edges. The bilberry has certainly larger leaves than 
these others, but notice in the early autumn how soon 
and readily they drop off, and leave the thick, green, 
ridged stem to do their work. The moorland grasses 
also have protected leaves ; generally they are narrow 
and pointed, and the whole leaf rolls over, so protecting 
the side on which are the transpiring pores (see p. 102). 
All these plants have the appearance of protecting them- 
selves from loss of water; how is it? It may seem 
strange when you remember that it is from our moor- 
lands that so much of our water supply comes, and also 
that the moors are common in the north, where there is 
a large rainfall. All the same, the plants on a moor do 
actually require to preserve their water, as they suffer 
from " drought conditions." 

Stand on a high moor on a windy day, and you will 
soon feel how the force of the wind sweeps across 
it. Such a day is what laundresses call " fine drying 



CHAP. XXIX. MOORLAND 155 

weather/' and so do the plants. Then if you go on 
a bright sunny day in summer, you will soon feel how 
very hot the moorland can be, for there is no shade to 
be had anywhere, and the cool green glades of a wood 
offer a tempting change. The moorland plants suffer 
from this heat, and require to protect their transpiring 
pores from the glare, so that you will find all those that 
can do so, have rolled their leaves up tightly. Then 
notice the soil of the moors, how springy it is, and how 
black and u rich " ; very often there are traces in it of 
the partly decomposed plants which form it. This is 
what is called a peat}- soil, and may even be true 
peat. The decomposing plants in this soil give rise to 
an acid which is rather preservative, and at the same 
time it acts on the living plants and makes it difficult 
for them to draw in water by their root hairs. This 
kind of soil adds very greatly to the " drought condi- 
tions " of the moorland plants, for it makes it hard for 
them to use the water which surrounds them. All these 
things cause the moorland plants to be as sparing as 
possible of their water, and so they have the appearance 
of plants grown under dry conditions. 

But why are there no trees on the moors, you may 
ask ! It cannot be that they are on too high a level for 
trees to grow, for some even higher hills are clothed 
with them. The truth is that probably long ago there 
were trees on the moors, but men cut them down fool- 
ishly without having planted young ones between ithe 
old ones, which would have replaced them. When 
once all the trees are cut down on a hillside, it is very 
difficult for young ones to get a start again, because 
everything which makes it hard for ordinary small plants 
to grow hinders the young trees, and the worst of all 
these things is the strong wind, which can rush un- 
checked over the bare moor. A strong wind is more 
powerful than a young tree, and kills it. 

The plantations of young trees which are to be found 
on the moorland have to be started on the sheltered 



156 MOORLAND CHAP. XXIX. 



side, and require much care and attention. You will 
notice that the trees which do grow there are those 
which are specially fitted for a hard life, such as the pine, 
larch, and birch. 

Another feature of the moorland, and one which can- 
not long escape our notice if we walk about moors at all, 
is the number of patches of wet moss which shake and 
tremble beneath our feet, and may form great stretches 
of bog-land. Sometimes this is so soft that it gives way 
altogether, and one may be knee-deep in moss and 
water, where it looked firm enough to the eye. You 
will find this bog moss grows in a peculiar way, the 
fresh green branches growing up and up, while below 
lie the half dead older stems, which are partly preserved 
by the peaty acids. These layers of moss collect for 
many years, till very thick masses of peat-bog may be 
formed. 

Among the bog-moss you will often find the sundew 
and butterwort (see pp. 114-15), which are two of 
our chief insect-eating plants. They love the boggy 
moorland, or a damp spot beside a little moorland 
stream. 

There is a curious thing you may have the chance of 
seeing in a wet moor. If you find a stream dripping 
over a ledge some little distance on to the rocks below, 
you may see how thick and beautifully green are the 
patches of moss growing beneath its spray. If the 
stream has passed over much limestone (and is therefore 
carrying some in solution), you may see below the 
living moss much dead moss just covered with a thin 
coating of lime. Below this is more moss, which has 
been made quite hard with the lime, and is brittle 
and snaps if you try to bend it, while below this 
again is a hard, compact mass of stone which is made 
from the stony stems of the moss crushed together by 
the weight above them and filled in with more de- 
posited lime. In some places great masses of rock 
are formed in this way. You have here, acted before 



CHAP. XXIX. MOORLAND 157 

your eyes, a piece of the history not only of the 
living and dying plants of to-day, but of the building 
of rocks, which may some day help in the building of 
mountains. 



PLATE V. 




WATER PLANTS GROWING PARTLY BELOW AND PARTLY ABOVE 
THE SURFACE OF THE WATER 



CHAPTER XXX. 



PONDS 

THE \vater of a natural pond is crowded with plant-life. 
Do not go to one in a London park, which is cleaned 
out by the County Council at intervals, but to one 
which is left to itself, and you will find it full of 
interest. 

Some of the plants float freely in the water, as do the 

duckweeds, and others, such 
as the water-lilies, are rooted 
in the mud with their leaves 
floating on the surface, while 
yet others are rooted in the 
mud at the bottom and live 
almost entirely under water, 
like some of the potamo- 
getons, or curly pond-weeds. 
The plants which are more 
or less attached to the muddy 
bottom, and have floating as 
well as submerged leaves, are 
perhaps among the most in- 
teresting, for they show two 
kinds of leaves. Look at a 
water buttercup, for example 
(fig. 141) ; on the surface of the 
water, or just above it, are the flowers and leaves, which are 
rather like the leaves of an ordinary buttercup. Follow 
the stem a little way down under the water, and you 

Avill see that the leaves are no longer simple, but are 

-159 




Fig. 141 . Water Buttercup, show- 
ing the much-divided water-leaves, 
and the simpler leaves rising into 
:he air. 



160 PONDS CHAP. XXX. 

split up into many hair-like divisions, which sway about 
easily with the water's movements. These two kinds 
of leaves are each suited to their position, as you will 
see if you think about them. The broad, undivided 
leaves on the top of the water expose their surface to 
the sunlight and do as much manufacturing of starch as 
possible, while the solt much -divided leaves below the 
surface are in keeping with their position, for they allow 
the current to pass between their fine divisions instead 
of pushing them up or tearing them, as it must do if 
they had broad, flat surfaces, which would be over- 
powered by the strength of the current. 

Compare these leaves with those of the water-lily. 
In the lily you find no divided leaves, but they all 
rise to the surface and float there, spreading their 
expanded blades on the water. Notice what very long 
leaf-stalks they have, sometimes eight or ten feet in 
length. Think how absurd the plant would look on 
dry land, with its short stem and its huge leaf-stalks, 
though they are so well suited for floating in the deep 
water. In the air the long, soft stalks would flop about 
on the ground, as they need some support, but this they 
get in the water, which buoys them up and saves them 
from expending too much material in the formation of 
strengthening tissue. 

Even those plants which, like the water marestail, can 
stand up by themselves some way out of the water, 
yet have softer stems than most land-plants, and far 
fewer well-developed " water-pipe " cells, because they 
are so surrounded by water that they can get it easily. 
Both these plants and the water-lilies, as well as many 
others, store air rather than water in their stems, and 
often the spaces in the meshes of the stem-tissue are 
filled with air, which acts both as an air reservoir and 
a buoy to float the leaves. We find all through the 
plant-world that the structure of a plant depends very 
much on the kind of conditions under which it is living, 
and in the case of those growing in the water, it is 



CHAP. XXX. 



PONDS 



161 




Fig. 142. Uuckweect, with 
simple leaves, and long roots 
hanging in the water. 



quite clear how the soft, air-filled stems are one result 
of their mode of life, and are 
well adapted to it. 

In the ponds you will often 
find that the duckweed grows 
in large masses on the surface. 
Each plant seems to consist of 
but one leaf and a slender root 
about an inch 
long, hanging 
freely in the 
water. Some- 
times two or 
more of the 
leaves are at- 
tached and 

form a little cluster, but it is exceed- 
ingly rare to find the duckweed in 
flower. Simple as it is, almost sug- 
gesting the algae rather than the flower- 
ing plants by its general appearance, 
yet the duckweed is really a flowering 
plant. It is, in fact, one of the very 
tiniest of flowering plants which are 
known. 

Floating with the duckweed are fre- 
quently many fine, thread-like algae, 
sometimes quite free, 
and sometimes attached 
to stems or rocks. 
They are very delicate, 
unprotected plants, 
their whole body con- 
sisting of simple rows 
of cells. Notice how 
their feathery tufts 
in a 



Fig. 143. Creeping rhizome of the Bulrush, 
which pushes out towards the middle of the 
pond. 



cling 



together 



close mass when they are taken out of the water ; 

( c 260 ) M 



162 



PONDS 



CHAP. XXX. 



they require its support and protection to enable them 
to live. 

There are many plants growing round the borders of 
the pond, half in and half out of the water, such as the 
reeds and sedges, irises and the tall marsh buttercups. 
Watch how these plants gradually grow further and 




Fig. 144. A water channel grown over by floating plants and the 
advancing reeds and rushes. 

further in towards the middle of the pond. They 
advance with their creeping underground stems (see 
fig. 143), and collect mud, dead leaves, and stalks around 
them, gradually building up a little firm soil round their 
roots. Slowly these accumulations from different plants 



CHAP. XXX. PONDS 163 

meet, and the whole gets more compact, till the plants 
from the shore which require soil are able to grow with 
them. 

In this way the shore slowly advances, the floating 
plants first building up some mud, and the reeds follow- 
ing and bringing shore plants in their train, till in the 
end the edges of the pond all meet in the middle, and 
the pond, as such, no longer exists. Only a marsh 
remains, till this may be gradually grown over by the 
ever-increasing land-plants, and an oak-tree may grow 
where once the water-lilies bloomed. If the advancing 
reeds at the edge had been kept cut back, as they often 
are, then the land-plants could not have taken such hold, 
and the pond would have remained a pond with all its 
" water-weeds." 



PLATE VI, 









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12 

1! 



s s 






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o -g 

Q PS 

O ^ * 
Z < rt 



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l-i 



CHAPTER XXXI. 

ALONG THE SHORE 

SANDY shores with dunes are so common round Britain 
that you will probably have opportunities of studying 
them Did you ever notice with any care what kind of 
plants grow on the sand next the sea? As you walk inland 
from the sea, you will find first little hummocks of sand 
with a few low, bent grasses, scattered and often far 
apart. Then as you go a little further inland, the sand 
mounds are higher, and a stronger grass grows first in 
tufts and then thickly over them ; this grass is the useful 
sand- binder, or marram grass, and grows on the shifting 
sand, quite near the sea (see fig. 145). Try to pull up a 
plant of this grass, and you will probably find out some 
of the things which help it to hold its position in the 
moving sand. It is not at all easy to pull up, and you 
will have to dig rather carefully if you are to get it out 
at all complete. 

You will find that what you thought was a simple 
tuft of grass is really connected, by an underground stem, 
with other tufts. If you follow this along, you will find 
that the underground stem runs for a long distance, 
burrowing in the sand and sending up tufts of leaves at 
intervals. The tip of the stem always remains under 
the sand, prepared to grow in whatever direction is best, 
and unless it is buried to a very great depth it will 
always continue growing. Coming off from the stem 
there are very many long roots, and at the places where 

the leaf tufts arise there are generally one or two much 

165 



i66 



ALONG THE SHORE 



CHAP. XXXI 



longer and stronger than the others, which run a very 
great distance into the sand, and if you wish to get 
them out without breaking them, you may have to dig 
for several hours. It is by means of these branching 
underground stems and long roots that the marram grass 
gets its hold on the sand. When once this grass holds 
the sand it is soon helped by a number of other plants, 





Fig. 145. A Sand-dune by the sea with the Marram grass in tufts, and 
the Carex tufts coming up in straight lines from their underground stems. 



which come on behind it and cover the surface, and so 
prevent the wind from scattering the sand-grains, and 
blowing them about in clouds. 

One of the first plants to follow the marram is the 
sea-star grass, or carex. You have probably seen its 
little tufts following in lines across bare banks of sand 
(see fig. 145). This appearance is due to the under- 



CHAP. XXXI. 



ALONG THE SHORE 



167 



ground stem, which runs very great distances in nearly 

straight lines, sending up groups of leaves at short 

intervals as well as side-stems, which form lines crossing 

the main line. 

Often a bank 

may be covered 

with lines of this 

plant. A little 

piece of the 

plant is shown 

in fig. 146, where 

you can see that 

the structures 

are on very much 

the same plan as 

those described 

for the marram 

grass. There 

are many other 

plants with this 

kind of habit, 

which enables 

them to live on 

the sandy shores 

and dunes. Look 

at all the plants 

you can find on 

the sand - hills, 

and you will see 

that in some way 

they have their 

parts adapted to 




suit their 
ditions. 
long roots 
a running 
these you 
dig up. 



Fig. 146. A small piece of the underground stem 
of Carex, \vith tufts of leaves coming above the level 
of the sand; (s) stem, (r) roots (cut off) with small 
side roots, (sc.) scale leaves underground. 



con- 
Very 

and 

stem are the commonest characters, and 
will find on almost every plant you try to 



i68 



ALONG THE SHORE 



CHAP. XXXI. 



Sometimes the stem can grow up and up, even 
though it is continually buried by 
the shifting sand, as you can see 
very well in the case of the sea 
holly. You may dig for more than 
a dozen feet before you come to 
the end of the vertical stem of what 
seemed to be quite a small plant 
(see fig. 147). 

Along the shore are other plants 
of quite a different kind, which have 
also special characters to help them 
to conquer a region which seems to 
be very inaccessible to land plants. 
Many curious plants live in the 
mud-flats that are frequently covered 
by the tides, and which can there- 
fore only get 
salt water. 
You re- 
member 
that salt 
kills ordi- 
nary land- 
plants, so 
that these 
must be 
specially 
built to be 
able to stand 
it. Most of 
them have 
very thick, 

fleshy leaves, and rather bushy 
stems, while others have leath- 
ery leaves covered with a kind 
of wax, or with hairs, which make them look grey. 
Look at the sea-daisy, and you will see that the leaves 




Fig, 147. Sea Holly, 
showing the plant at the 
surface, and the long stem 
below the level of the 
sand (s). 




Fig. 148. Marsh Samphire or 
Glasswort, a plant with swollen 
green stems which do the work 
of leaves. 



CHAP. XXXI. ALONG THE SHORE 169 

are very thick and juicy ; so are those of the sea-blite 
and salt spurry. The boldest of all these plants, the 
marsh samphire, which goes furthest out to sea, and 
may grow on bare mud covered by every tide, has 
not leaves at all, but very thick, fleshy stems, which 
are green and do the work of leaves (see fig. 148). 

All these forms must remind you of the plants which 
were characteristic of dry regions ; how is it that these 
plants, often actually growing in the water, should yet 
be specialised in the same way? It is because all the 
water they get is salt, and it is very difficult for them to 
live in it. They can only use a relatively small quan- 
tity, otherwise the} 7 would be forced to take in too much 
salt, so they must prevent their leaves from transpiring 
much and using the water up. In this way they are really 
in the same kind of position and so require to have the 
same kind of leaves as a plant growing where very little 
water of any kind is to be had. They are in the same 
difficulty as the Ancient Mariner, with "Water, water 
everywhere, nor any drop to drink." 

Pull up a marsh samphire, and you will see that it 
has a very much branched, spreading root, which gives 
the plant a firm grip on the sand or mud, but it has 
not long roots like the sand-dune plants, for all the 
water which it can use is to be had quite easily and is 
near at hand. 

You may notice, too, on these mud flats the mingling 
of plants from land and sea. When the marsh samphire 
and sea-daisy invade the flats which are covered every 
day by the tide, they are entering the region of the sea- 
plants, and you may find them growing side by side 
with the true seaweeds, and even in some cases we may 
notice the bladderwrack seaweed further in toward the 
shore than the samphire, which has ventured far out to 
sea. 

As you will find in everything in nature, it is always 
difficult to draw a fixed line and say that on one side lies 
one type of thing, and on the other side something 



170 ALONG THE SHORE CHAP. XXXI. 

different ; so, in dealing with different " plant associa- 
tions," we find that they have their special regions, but 
that they tend to cross over any limiting lines set 
between them. In deep water and on high, dry land, 
we find quite different kinds of plants which never 
mix with each other, but on the border land between 
such regions the boundary is not strictly kept, and we 
sometimes find plants growing where we might expect 
the conditions to be unsuited to them. 



PLATE VII. 




BLADDERWRACK GROWING ON THE ROCKS EXPOSED 
AT LOW TIDE. 



CHAPTER XXXII. 

IN THE SEA 

ALL the plants which grow in the sea are hastily grouped 
together by most people under the name " seaweeds." 
We know that there are many kinds of seaweeds, and yet 
even to one who has not studied them, they do not seem 
to differ so much from each other as to deserve special 
classes. And this general view is quite a correct one, 
for with very few exceptions, all the plants which 
actually live in the sea are algae, and so belong to the 
simplest family of plants (see Chapter XXVII.). Yet 
they are not without interest and individuality. In the 
sea these simple plants have everything to themselves; 
and it is there that we get them developed in a very 
special way. 

You must have noticed that you never find seaweeds 
actually rooted in the sand (except in protected marshes, 
where the sea samphire and some flowering plants may 
grow), because sand is always shifting and being churned 
up by the waves, so that they cannot get a firm hold. 
This is almost the same on the pebbly shores where the 
stones are rolled over by the waves, and so would batter 
any unfortunate plant growing on them. If you go 
along a rocky coast at low water, however, you will find 
countless true seaweeds, growing so thickly that the 
rocks are covered by their slimy masses, while in the rock 
pools are beautiful tufts of more delicate seaweeds of all 
colours (see Plate VII.). 

Examine a single plant of bladderwrack or fucus, and 
pull it up if you can. You will find that it is very slimy 



173 



174 IN THE SEA CHAP. XXXII. 

and slips out of your fingers, and then, that when you 
have got a firm hold on it, it sticks so fast to the 
rocks that it is difficult to get it off without breaking it. 
Does this mean that it has roots which go right into the 
rock as the roots of land-plants go into the soil ? Find a 
plant growing on a small stone, if possible, and look closely 
at it ; the " root " does not go into the stone at all, but 
is much divided and clasps round it, bending into every 
little crevice and sticking tight. Note, too, that there 
are no root hairs as there are in land-plants, which is 
natural enough when the whole plant is growing in 
water, and can therefore absorb it through all its surface. 
All that is required from the " root " is that it shall 
hold firmly on to the rocks and keep the plant from 
being dashed on to the shore by the waves. The " root " 
is not a true root, but is really only a part of the simple 
body, which is specially adapted for attachment. 

The many large bladders on the plant are filled with 
air, as you will see if you split them open, and they help 
to buoy it up in the water. Notice, too, how flat the 
whole plant is ; it is really a single sheet of tissue 
or "thallus," which is much divided, but does not 
branch in many directions as a land-plant does. All 
these characters are those of the simple family of algae, 
to which all the seaweeds belong. Though in some 
cases they may form what look like very complicated 
structures, yet they are always built upon these simple 
lines. 

Often you may find little plants growing on the bigger 
ones ; sometimes a well-established weed may be almost 
covered by small seaweeds of many kinds, brown, green, 
or red. These attach themselves to the big plant in 
much the same way as they would to a rock, but only 
use it as a place of anchorage, and do not tap its food 
supply, as the parasitic mistletoe does to the land-plants. 
In the same way you may find numbers of seaweeds 
planted on shells or growing on the backs of crabs. 

As the tide goes out it gradually exposes the rocks 



CHAP. XXXII. 



IN THE SEA 



175 



and pools with their innumerable inhabitants. Now in 
the case of those which are first uncovered, a long time 
must pass before the water returns, while those quite 
near the low water level are only uncovered for a little 
while. Follow the falling tide some day, and look for 
the effect \vhich this difference (in the time for which 
they are exposed) has on the plants growing at different 
depths. 

As you go out towards the low water mark you will 




Fig. 149. The Laminarias, which are only exposed at quite low water. 

find first and commonest the bladderwracks, which get 
more luxuriant where they are a little removed from the 
region of the pounding waves at the actual shore. 
Then further out you will find that the bladderwrack 
gives up its place to another plant very like it, but 
with more jagged margins. Beyond this you will come 
to the big strap-shaped laminarias, which never grow 
where they are very long exposed without water (see 

149). 
These different regions of seaweeds (some of which 



fig. 



176 IN THE SEA CHAP. XXXII. 

are only laid bare by the tides which go very far out) 
really depend on the fact that the different levels of 
the shore are left exposed for varying lengths of time 
according to their depth. If the shore is flat or gently 
sloping, then the tide has a very great distance to 
recede before the same depth is reached as would be 
attained much nearer in where the shore slopes steeply 
(see fig. 150). This explains how it is that in one place 
you may have to walk out a quarter of a mile till you 
come to the region of laminarias, while in another 
you need walk no distance, but merely clamber down 
the rather steep rocks to get to it. But as the actual 
time taken by the falling tide is the same in both 



H. 




Fig. 150. A diagram to show how the slope of the shore influences the distance the 
tide goes out, and, therefore, the distance from high-water mark at which the different 
seaweeds grow. A, a gently-sloping shore ; B, a steep shore. The line H indicates 
the high-tide level, and L the low-tide level. 

cases, the plants at any level are left exposed for 
almost the same time whatever the kind of shore 
may be. 

One thing that may perhaps puzzle you about the 
seaweeds is their colour ; some few of them are green, 
but most are blackish, brown, or even red. How then 
do they build their food? It is found that true chloro- 
phyll is present as well as the other colours, and that 
though they hide the green tone from our eyes, they do 
not hinder its activity in the plant. You can see that 
the brown bladderwrack is really a green plant if you 
soak some of its tissues in hot water ; the brown colour 
will be washed out and will leave the plant bright green. 



CHAP. XXXII. IN THE SEA 177 

In almost all cases these simple algae living in the sea 
are self-supporting plants, which have adapted them- 
selves to the special conditions in the depths of the sea 
where no flowering plants can live, and there they reign 
supreme. 



( C 260 ) 



CHAPTER XXXIII. 



PLANTS OF LONG AGO 

WHEN we were on the moors we noticed that we may 
sometimes find plants being actually turned to stone 
under our eyes (see p. 156). These are plants which are 
living at the present time, but this same thing has also 
happened to plants which lived long ago, and which 
otherwise we could not see and study, because they are 
all dead. In those cases in which they did not decom- 
pose in the ordinary way after death, but were turned to 

stone, we are 
* sometimes 
able to find 
out almost as 
much about 
them as we 
can about the 
plants living 
to-day. 

You must 
have seen in 
, museums, or 
even found 
.j for yourself 
in stones, the 
remains of 
leaves and 

stems of plants which, too, are turned to stone, but which 
yet show the shape and form of the plant with great 
beauty. If you go to the north of England, where there 
are many coal-mines, you will have a good chance of 




Fig. 151. Plant which was living at the time coal was 
made, pressed in a stone and so preserved. 



CHAP. XXXIII. PLANTS OF LONG AGO 



179 




finding pieces of stone which have been thrown out 
from the mines as refuse, and which have in them or on 
them most beautiful leaves of ferns and other plants. 
We know from geologists that these rocks are very old 

indeed, older 
than the val- 
leys and downs 
of the south of 
England, yet 
we can see to- 
day what the 
plants which 
lived then 
looked like, 
because they 
have been 

Fig, 152. Fern which was living at the time of the turned into 
coal, pressed between sheets of stone. stone and kept 

for us in the 

rocks till the miners dig them out when digging the 
coal. 

But what is coal itself ? You know that it is not at 
all like an ordinary rock, for it burns as well as wood, 
and has been found to be largely made of carbon. Even 
directly on top of the coal, and sometimes actually in 
the coal seams, we find plants preserved, and geologists 
and botanists have combined to prove that coal is really 
entirely composed of the crushed remains of ancient 
plants. 

You will remember that we found that many of the 
plants in the peat bogs did not get decomposed entirely 
because of the preservative peaty acids present in the 
water and soil. Something of the same kind happened 
to the plants of the old forests which now form our 
coal. As they died they did not entirely decompose, 
but got pressed tightly together, all their" living juices 
being squeezed away till little but the carbon in them 
remained. These masses of plants gradually sank 



iSo 



PLANTS OF LONG AGO CHAP. XXXIII. 



beneath the sea, were covered by sandstones and 
limestones, and were preserved between the beds of 
rock, forming masses nearly as firm as the rocks them- 
selves. These old plants, which to-day act as our fuel, 
are really " as old as the hills," for they were growing in 
the country before the hills were made. 

As well as the many plants which were preserved in 
this way, and in which we can now see little but masses 
of carbon, there were others which were preserved in 
stone, sometimes pressed between the layers of stone as 
you press a flower between sheets of blotting-paper, in 
other cases turned directly into stone without crushing, 

so that they 
show their 
complete 
form, cell by 
cell. It is 
from these 
stone plants 
that we learn 
what the 
plants of the 
coal were 
like. Some- 
times we find 
great trunks 

of trees standing petrified together in the positions in 
which they were growing, with their roots twining round 
one another, and entering the muddy soil on which they 
lived. Sometimes such tree-stumps stand up through 
the coal-beds and rocks which must have been deposited 
all round them (see fig. 153). We find also leaves and 
stems, cones and seeds, in the stones, till we can build 
up completely the form and life history of several of the 
plants which were then living. But in all the wealth of 
material which has been found, no flowers have ever 
been discovered. The seeds seem to have belonged 
to plants of the pine-tree family, so that these old forests 




Fig. 153. The trunk, A, of a fossil tree turned into stone, 
still standing in the position in which it grew. It is sur- 
rounded and covered by the pressed masses of plants (coal) 
C, fine mud (shales), O, and sandstones, S. Its roots, R, 
are still in the clays, U, in which they grew, which are now 
hardened to rock. 



CHAP. XXXIII. PLANTS OF LONG AGO 181 

were without any of the plants which are to-day the 
most important family of all, that is, the flowering plants. 
They lived so long ago that flowers had not come into 
existence by that time. 

Another strange thing about these forests is, that 
although there were great trees in them, they were not 
like those of our present forests. To-day our trees are 
chiefly flowering plants, such as oaks, limes, and beeches ; 
but the giants of these ancient forests \vere club-mosses 
and horsetails, plants belonging to the fern tribe. Their 
descendants, the club-mosses and horsetails growing 
now, have degenerated, and are humble plants not 
more than a few feet high at the most, and always of 
little real importance in the landscape. 

The true ferns then living seem to have been more 
like those of the present, though perhaps a little larger 
and more important. In the family of ferns then living 
were some with strange histories, and among the ferns 
which you may find in the stones some leaves may have 
belonged to a plant which was truly a " missing link" in 
the history of plants, and helps us to see the relation- 
ship between ferns and pines. 

Many and strange are the tales the fossil plants can 
tell us of the life in the forests when the coal was made, 
and just as, in the moors, only those moss-plants which 
were turned to stone will still be there after centuries 
have gone by, so it w r as in the old coal-forests that only 
the plants which were turned to stone remain to tell us 
their story to-day. For this reason our knowledge of 
the forests of long ago is not complete ; but even now it 
is enough to tell us something of the life of the plants 
which were then doing the food-building work of the 
world. Though the individual plants were so different, 
the " associations " were in a general way the same as 
those now living. Great trees reared their heads into 
the air, and below them, or climbing round and over 
them, the smaller plants found place long ago as they 
do to-dav. 



CHAPTER XXXIV. 
PHYSICAL GEOGRAPHY AND PLANTS 

IF we examine the plants of any district, we find that 
a number of outside influences affect them very greatly. 
The most important of these are the physical geography 
and geology of the place. The form and nature of the 
rocks and soil, as well as the climate, have a great effect 
on the plants growing in any spot. 

You can see this in an extreme case if you imagine 
yourself up in a balloon looking down on England as on 
a map. In certain places you see lakes, that is to say, 
the rocks and soil are so arranged that they form a basin 
and hold the water permanently there. Now in a lake, 
as you know, only water-plants will be growing, so that 
the presence of a fairly deep and constant lake makes it 
quite certain what kind of plants must grow in that spot. 
Imagine an earthquake or some slower earth-movement 
which is strong enough to change the rocks so that the 
water all runs away, and the result is that there will be 
dry land in the same spot where before was the lake. 
This will cause the water-plants to die sooner or later, 
and land-plants will replace them. 

There is continual change in the arrangement of lakes 
and rivers, hills and shores, which takes place all around 
us, but so slowly that we do not notice it. It is slow, 
and therefore there is not a sudden killing off of any one 
kind of plant, and a rapid incoming of a different set 
of plants, but it causes a gradual shifting and moving of 
the groups among themselves. Sometimes there may 
be some swift and sudden change, as the result of a 

landslip or volcano, or in a stream or lake which has 

182 



CHAP. XXXIV. PHYSICAL GEOGRAPHY 183 

been artificially drained, which shows us a very good 
object-lesson in plant geography. 

The importance of the physical form of any place, 
however, does not only lie in the position of its lakes and 
streams and the size of its hills. The kind of rock, and 
nature of the soil covering the rocks, are very important, 
as well as the many other details of the land. 

In England there are no very high mountains, so that 
you cannot study the effect of great heights on plants, 
but all the same England affords quite sufficient oppor- 
tunity for the study of physical geography in its relation 
to plant-distribution. 

Even in the cultivated fields, where man tries to help 
the plants to overcome their surroundings, you will find 
the influence of the soil is very largely felt. Ask any 
farmer about his land, and he may tell you that a certain 
one of his fields is specially good for potatoes, another 
for barley, or that in a village a few miles away they can 
grow splendid crops of strawberries, while his are not 
worth the planting. Then think of the different kinds 
of plants for which the different counties of England 
are noted. Xo one could get the produce of the cherry 
orchards and hop-gardens of Kent to grow on the York- 
shire moors. Nor do we find acres of heather moor on 
the downs in the south of England, but instead there is 
a short turf with many little flowers which love the 
chalk and limestone, such as the blue ana white poly- 
gala, rock roses, and several small orchids. 

Now what is the difference between the north and 
the south of England ? It is chiefly one of rock and 
soil. On the Downs in the south you find a thin coating 
of brown earth over thick masses of white chalk through 
the surface of which the water supply quickly runs, so 
that we get few streams or bogs. In the north the hills 
are built of coarse sandstones, hard grey limestones, and 
fine black shales which hold much water, so that there 
are many swampy places and innumerable streams and 
little waterfalls. Then, again, the land in the north of 



184 PHYSICAL GEOGRAPHY CHAP. XXXIV. 

Kent, which is so famous for its cherries and hops, is a 
rich, fine clay, with a muddy and sandy soil, which 
centuries ago was the bed of a great river, and now is 
the most important factor in making Kent one of the 
most fertile parts of England. 

If we find that the influence of the physical nature of 
the land is so strong even in the case of cultivated 
plants, which are helped by man's knowledge, we shall 
expect to find that it is still more felt by the wild 
plants. 

Let us go, for example, to the moors east of Settle, in 
Yorkshire, where you find the three kinds of rock, the 
hard limestone, coarse sandstone, and soft, black shales. 
If you walk across the moors, you will see that the prin- 
cipal plants are heather, bilberry, and several coarse 
grasses, which grow in more or less irregular patches. 
If you notice the grasses carefully, you will find that 
they are of several different kinds, showing varieties in 
their size, form of leaf, colour, and so on, and that very 
frequently the different kinds grow on the different 
types of rock beneath them. After a little experience, 
you will almost be able to tell what is the nature of the 
rock on which you are standing by the appearance of the 
plants at your feet. 

If you live anywhere in the south of England, walk 
over some part of the downs till you see below you in 
the valley a clay-pit or pottery factory, which shows 
you that the chalk is no longer under the surface soil, 
but that it has been replaced by clay. Walk straight 
towards this place, collecting the plants you meet on the 
way. On the actual downs you will find many which do 
not grow near the clay-pit, since they are special chalk 
lovers. In the clayey valley it is very likely that you 
may find a pond ; if so, walk towards it, noting all you 
pass on the way. As you get to the edge, reeds and 
bulrushes, water forget-me-not, tall spikes of water 
loosestrife, and many others appear which you would 
have been astonished to meet with on the downs. 



CHAP. XXXIV. 



AND PLANTS 



185 



A very important factor also is the amount of rain 
which the district gets. This tells particularly among 
the ferns and mosses. Along the hedgerows of Kent, 
for example, where it is rather dry, true ferns will 
seldom grow, while in Devonshire every hedge and 
bank has many hundreds of the common polypody fern 




Fig. 154. A recently formed pond in Delamere with a dead forest tree 
standing up in the middle. 

and the hartstongue. When we come, however, to con- 
sider on what it is that the rainfall depends we find that 
it is the structure, size, and relations of the land masses 
to the sea and the winds. In fact, it depends on the 
physical geography of England as a whole. So that in 
the end the plants and the physical nature of anyplace 
are so much in touch that it is almost impossible to do 
anything in the study of plant distribution without 
considering physical geography. 

Although the changes in physical geography which 



i86 



PHYSICAL GEOGRAPHY 



CHAP. XXXIV. 



made and unmake continents are slowly acting around 
us all the time, it is not often that we can clearly 
see them taking effect. Photos 154 and 155 are 
therefore particularly interesting, for they show one of 
the processes at work. Part of a forest is in the actual 
course of being killed by the pond which is forming on 




Fig. 155. A recently formed pond which has covered a large area of the 
forest and killed many of the trees. Notice the dead trunks standing and 
lying about, and the rushes growing near the edge, which would not have been 
there but for the coming of the water. 

sinking land. This pond and several smaller ones of 
the same kind can be studied in the neighbourhood 
of Delamere forest, in Cheshire. Here the under soil 
gets washed out in certain places, and the surface 
earth sinks and forms a hollow in which water collects. 
In fig. 154 you see one tree standing in the middle of 
the pond. It is dead, and has been killed by the water 
(you remember that ordinary plants are drowned by 
too much water) and in fig. 155 you see a large area 



CHAP. XXXIV. AND PLANTS 187 

entirely covered with water, and the dead trees stand- 
ing up through it. This pond is spreading rapidly, and 
is a good illustration of the reverse condition from that 
seen in fig. 144, where the plants by their growth are 
filling up a pond. The washing out of the soil and the 
collecting of the water in this case was quite beyond the 
control of the plants themselves, but they are supremely 
affected by it. 



CHAPTER XXXV. 

PLANT-MAPS 

IN the last chapter we noticed a few of the many facts 
which show us that a close relation exists between the 
plants and the nature of the land on which they grow. 
We may now try to express these facts in a simple way 
by making maps of the land according to the plants 
growing on it. 

There are maps of the whole of England, made by the 
Government, which show all the roads and houses, the 
chief rocks, hills, ponds, and so on. The geologists 
have taken these maps and added to them details of the 
kinds of rock and soil of which the land is built. If 
now we take fresh copies of the u ordnance " maps, as 
they are called, and put on them all the plants growing 
in different associations, we can compare the resulting 
" plant-maps" with the land-maps of the geologists, and 
I think you will be surprised to find how much the 
plant-maps and land-maps correspond. 

To do this on a large scale, however, is far too big 
a piece of work for one person, or a few people, to 
attempt. We can only do some small piece of work on 
one area which will show how the rest is done, and 
yield some interesting details. 

Let us suppose, for example, that the moor east of 
Settle is to be mapped. First get an ordnance survey 
map on a large scale 25 inches to the mile is the best, 
but the 6 inches to the mile will do. On the map are 
marked all the walls, streams, and even some of the 
bigger trees, so that it is easy to find on it the exact 
spot where you are standing. For working you should 



CHAP. XXXV. PLANT-MAPS 189 

cut the sheet up into at least eight pieces, of regular 
size and shape, and use one of these at a time in the 
field. 

First get to know the part you are to work on later 
in a general way, noting the chief plants and in what 
way they are associated. 

Be careful in working to keep your sheets in regular 
order, and begin with the one at the bottom left-hand 
corner of the whole map. Find the exact spot on the 
ground which is represented by the point of the bottom 
left-hand corner of your first sheet, and put a white 
stake into it at least two feet high ; it is better if you 
add a little red and white flag, so that you can see it 
from a distance. Then find each of the other four 
corners of your small sheet, measuring the distance from 
a wall or tree if need be, and put in each a white stake 
similar to that marking the first corner. If your map 
is on the 25-inch scale, and you have cut it into sixteen 
equal pieces, you will find that the area staked out on the 
ground represented in one piece is not so large but that 
you can see over it, and by walking about within it, get 
all the features of the plants growing there mapped out 
on to your sheet. In studying the different patches of 
plants, you will find that, as a rule, in each there is one 
important plant which grows in great numbers, while 
there are many more scattered and less important species 
growing with it. Such patches of plants growing to- 
gether may be called Associations, and in mapping we 
only pay attention to the chief of these. In a patch 
where cotton-grass is the most conspicuous thing, there 
may be also half a dozen small grasses and plants grow- 
ing with it, in which case everything but the cotton 
grass would be ignored in the mapping, and the associa- 
tion called the "cotton grass" association. Similarly, 
a patch where heather is the most important plant would 
be called the heather association. Sometimes you may 
find two or more plants growing together which seem 
to share the area between them, so that it is impossible 



190 PLANT-MAPS CHAP. XXXV. 

to tell which is the chief one ; in such a case where, for 
example, heather and bilberry are apparently equally 
important, the association would be described as 
"heather-bilberry." For the sake of reference, lists 
should be kept of all the plants of less importance 
growing in the associations, though they are ignored in 
the mapping. 

At the beginning it is wise to go over the area and 
find out roughly how many chief associations there are 
in it, and to make out a list of them. Then choose either 
a colour or a sign to represent each of them in the map- 
ping, a colour will generally be found to be clearer arid 
more effective in the finished map, though a sign is very 
useful for the field-work. 

When all these preliminaries are finished, begin the 
actual mapping by going very carefully over the different 
patches in the staked-out area of one piece of the sheet. 
From the details already printed in the ordnance 
survey map, you will generally be able to find the exact 
position of the patches of plant associations (unless they 
are very small, when they must be ignored), and you 
should soon be able from the help of the given details 
to fill in the shape of the patches by the eye. If in any 
case this is difficult, a 5-foot rule and a string of 20 feet 
or 30 feet marked out into 5 feet and i foot lengths will 
be found very useful. From the actual measurements 
you will then get, it is easy to find how much will repre- 
sent them on the map by the simple sum : 1,760 actual 
yards are represented by 25 inches on the map, so that 
1 6, 10, or whatever number of feet you require will 

2< in. x 10 in. 2< in. x 16 in. 
be represented by ^^ or- ^ x g and 

so on. 

Do all your field-work in pencil, and take notes in a 
" field-book" as you go, so that you will be able to copy 
out a neat, correct map at home in which to colour in 
the associations and outline the patches with waterproof 
ink. When one of the sheets is done in this way, stake 



CHAP. XXXV. PLANT-MAPS 191 

out the area for the next, and so on, till you have all the 
sheets finished. Then paste them together again on a 
piece of muslin in their proper order, and you will have 
a complete " plant-map " of one definite, though small, 
area. This can be easily compared with a geological 
map of the same area, though the geological one will be 
on a rather smaller scale (best 6 inches to the mile), and 
you will see how the patches of plants frequently follow 
the arrangement of the rocks. This does not show so 
clearly on too small an area ; the larger the district you 
can cover the better. 

To work from an ordnance survey map is the easiest 
way of proceeding, but if you like to combine the plant 
study with a little simple survey work, it is quite possible 
to make the map from the very beginning. This is not 
generally worth the trouble, except in cases where you 
find a rich and interesting area which would repay very 
careful mapping on a larger scale than the survey have 
published. For example, it would be a very good plan 
to choose some small area, and in it stake out exactly 
100 feet square. Along the sides plant smaller stakes 
every 20 feet, and map all the details very carefully on 
to mathematical paper on the scale of either 5 inches or 
better, 10 inches to 100 feet. Such an area would well 
repay the trouble of repeated mapping at different times 
of the year. If you have a series of maps of the exact 
area every two months, for example, you will be able 
to see from them very well the succession of plants 
throughout the year, and how the associations change 
according to the seasons. 

Another thing that should go with the mapping is the 
plotting out of " sections" through the irregular land, 
which will show clearly how frequently the plants 
growing on any spot are determined by the level of the 
spot and its consequent relation to the water supply. 
The most striking case of this kind is that of a section 
through a pond or stream and its banks. Unless you 
have a boat at your service, you will have to choose a 



CHAPTER XXXVI. 

EXCURSIONS AND COLLECTING 

WHEN you plan an excursion do not take your collecting 
tin and a " Flora" in which to look up the names of all 
you find, and then imagine that you are fully prepared 
for a day's botanising. It is, of course, a very useful 
thing to learn the names of the flowers you find, because 
you cannot even speak of a plant if you do not know its 
name, but the mere naming is in reality the least interest- 
ing and important thing about them, as you will know 
if you have followed the study of plants in the way 
suggested in this book. 

In arranging an excursion, or what is far better, a 
series of excursions into the country, the most important 
thing to have is a plan of action. Do not wander aim- 
lessly in the woods, attracted from side to side by all 
that comes in your way ; choose rather some special set 
of things to collect and study. If there are several of 
you together, then each one should have a particular 
subject about which to make notes and collections; then 
afterwards all the members of the excursion party should 
meet together and compare their results, and show each 
other any interesting specimens obtained. 

Each person should be provided with : A tin collect- 
ing-box, a strong knife or digger, a note-book, pencil, 
and magnifying-glass, some string, and a fine knife. 

In case you find it difficult to decide on special things 
to do, here is a list of a few of the many suitable subjects 
which may be chosen. The list is not at all complete, 
but it may give you a few ideas at the beginning of 
your field-\vork. 



CHAP. XXXVI. EXCURSIONS AND COLLECTING 195 

1. In the early spring, study particularly all the plants 
which are flowering. Dig up complete specimens of all 
the smaller plants, and notice how many of them have 
some special means of storing food underground through 
the winter, such as bulbs, tubets, and so on. This stored 
food makes it possible for the flowers to bloom before 
the leaves have done any work, a thing which would be 
impossible in the case of ordinary young plants. Our 
" early " spring flowers are really late flowerers, as they 
bloom on the result of the food made in the previous 
year. Make drawings, or press a series of these. 

2. Collect buds and opening buds, getting series of 
scales from the outer hard ones to the inner developed 
leaves, and press them. 

3. Notice, and make sketches of, the different ways in 
which leaves are folded in buds: the fan-like beech, 
the coiled fern, and so on. 

4. Collect seedlings ; notice specially those of trees. 
Study the form of their earlier leaves, which are gener- 
ally simpler than the mature ones. 

5. In summer, collect as many forms as possible of 
full-grown leaves. Compare and classify them accord- 
ing to their nature and shape : those which are simple 
or compound, and then in more detail. Dry and mount 
a series of representative ones. 

6. Study very particularly flowers in relation to their 
insect visitors. For this it is better to remain a long 
time in one place, so that it is not so good for a general 
excursion, but is splendid if you can get off for an early 
excursion by yourself, or with one or two companions. 

7. Make collections and lists of all climbing plants, 
noting by what means they climb. 

8. Keep a list for the whole year of the colours of the 
flowers as they come out, noting in general which are 
the most characteristic for the different seasons. 

9. Collect fruits, and arrange them according to the 
way they scatter the seeds. 

10. When the leaves are falling, notice where thev 

(C260) O2 



196 EXCURSIONS AND COLLECTING CHAP. XXXVI. 

break away, and what form of scars they leave. In the 
case of compound leaves, whether they fall off whole or 
in parts. 

11. Collect series of plants which are growing together 
in different places, e.g., those in a woodland glade, those 
at the edge of a pond, those on a sandy hill, and so on. 
Dry them by pressure between sheets of paper, and 
mount them, noting how their forms correspond to their 
surroundings. 

12. Go to the same spot in a wood in spring, summer, 
autumn, and winter ; make notes and drawings of what 
you see each time. In the spring there will be a carpet 
of flowers under the bare trees, note what happens in the 
summer, and later on. 

These suggestions are only a beginning, and special 
problems will arise of their own accord in connection 
with the work you are doing, till you find that the real 
excursion becomes the most interesting and important 
part of your work. If we go to the plants themselves 
and ask them to teach us, they will never fail to give 
us the chance of learning lessons of ever-increasing 
interest. 



INDEX 



The roman numbers refer to the pages, and italicised numbers to 

the figures 



ABSORPTION by roots, 33, 21, 22 

Adventitious roots, 56, 40, 57, 41 

Alcohol, 24 

Algae, 141 

Algae in ditches, 151 

Algae in the sea, 143, 134, 173 

Ampelopsis, 108, 105 

Animals eaten by plants, 114 

Animals, life of, 3, 7 

Anther, 80, 81 

Assimilation (see Food building) 

Associations of plants, 152, 189 

Axil of leaf, 75, 66 



BACTERIA, 144 
Bean seeds, 8, 3, 9, 4 
Bean seedlings, 10, 6, n, 7 
Bean seedlings grown in dark, 

38,27 
Bean seedlings, growth of, 41, 

28 

Beech leaf, 65 
Bees and flowers, 119 
Bidens, fruits of, 90, #7 
Bilberry, 154 

Bladderwort, 116, 115, 114 
Bladderwrack, 144, 135, 173, PL 

Bog-land, 156 
Bracken fern, 133, PI. 1. 
Bramble, 63, 49 
Bread, starch in, n 



Breathing of animals, 6, 2 

Breathing of plants, 5, I, 96 

Breathing pores, 96, 96 

Broom, 62 

Broomrape, 113, 109 

Buds, 72 

Buds of fern, 134, 127 

Buds of horse chestnut, 72, 62, 

63 

Buds, overlapping scales of, 73, 

63,64 

Bud scales, 74, 65 
Bud scars, 75, 66 
Buds of sycamore, 75, 66 
Buds, unfolding of, 72, 62 
Bulbs, 77, 68 
Bulrushes, 151, 138 
Bulrushes, rhizome of, 161, 143 
Bur, fruit of, 90, 86 
Buttercup, flower of, 82, 76 
Buttercup, water-, 159, 141 
Butterwort, 115, 112 



CACTUS, 2, 62, 48, 99 

Calcium phosphate, 15 

Calcium sulphate, 15 

Calyx, 79, 70 

Canadian water-plant, 21, 13 

Capsule of moss, 139, 131 

Capsule of poppy, 89, #5 

Carbon, 19, 23 

Carbonic acid gas, 6, 19, 24, 27 

Carex, 1 66, 146 

Carpel, 82, 76, 77, 78 



i 97 



198 



INDEX 



Carrot, 55, 3$ 

Caustic potash, 20, 12 

Cells, 92, 97 

Cherry flower, 82, 78 

Cherry fruit, 88, 82 

Cherry leaf, 64, 50 

Cherry leaf arrangement, 69, 58 

Cherry stipules, 64, 50 

Chlorophyll, 17, 24, 27 

Circulation of water, 28 

Climbing plants, 104 

Climbing assisted by roots, 106, 

101 
Climbing by tendrils, 107, 104, 

108, 105 
Climbing by twining stem, 106, 

102, 107, 103 
Clover attacked (by dodder, no, 

10(5, 107 
Club-moss, 137 
Coal, 153, 178 
Collecting, 194 
Colour of petals, 80 
Cones of pine, 127, 128, 123 
" Control plant," 16 
Convolvulus, twining of, 106, 102 
Cork, 95 

Cornflower, 121, 122 
Cotyledons of bean, 9, 4 
Cotyledons of pine, 129, 130, 126 
Cotyledons of rose, 66, 54 
Cow- wheat, 113 



DAHLIA, roots of, 56, 39 
Daisy, flower of, 121, 121 
Dandelion, fruit of, 88, #3 
Darkness, effect on growth of, 

38,27 

Dead nettle, 68, 56, 149, 137 
Deserts, 100 
Dicotyledons, 126 
Distilled water, 15 
Ditches, 150 
Dodder, no, 106, 107 



Downs, 183 

Duckweed, 151, 139, 161 

Drowning, of trees, 185, 



ELDER tree, twig of, 96, 96 
Elodea, 21, 13 
Embryo, 9 
Excursions, 194 
Eyebright, 113 



FERNS, bud of, 134, 127 
Ferns, family of, 133 
Ferns, fossil, 179, 152 181 
Ferns, prothallium of, 135, 129 
Ferns, spore-cases of, 135, 128 
Ferns, u sporeling " of, 136 
Flowers, 78 
Flowers in relation to insects, 

118 

Flowering family, 125 
Food-building in leaves, 23 
Food materials, 14, 18 
Food solutions, 15 
Fossils, 179, 151 
Fossils, tree, 180, 153 
Foxglove flower, 119, 117 
Foxglove in hedges, 146, PI. IV. 
Fruits, 86 
Fucus, (see also Bladderwrack), 

173, PL VII. 
Fungi, 109 
Fungi, spores of, 143 
Fungi, structure of, 142, 133 



GOOSE-GRASS, leaves of, 69, 60 
Goose-grass, fruit of, 90, 87 
Gorse, 102, 99 
Gorse, flowers of, 119, 119 
Grass, leaves of 66 
Grass, roots of, 54, 37 
Gravitation, 44 
Growth, 40 



INDEX 



199 



Growth, direction of, 41, 29, 43, 

3 
Growth, region of, 40, 28 



H 

HAIRS, 96 

Harebell, 78, 69 

Heather, 154 

Hedges, 147, PL IV. 

Holly, 54, 36 

Honeysuckle, leaves of, 68, 57 

Hop, 106 

Horse chestnut, buds of, 72, 62 

Horsetail, leaves of, 69, 59 

Horsetail, family of, 137 



I 

INDIARUBBER tree, leaves of, 31, 

20 

Insects and flowers, 83 
Iodine, n 
Iron chloride, 16 
Iron, importance of, 17 
Ivy, adventitious roots of, 56, 40 
Ivy, climbing of, 106, 101 
Ivy as host plant, 112, 109 
Ivy, leaves of, 65 
Ivy, position of leaves of, 37, 26 



LAKE or pond-maps, 193 

Lamina of leaf, 64, 50 

Laminarias, 175,149 

Larch, branching of, 59, 44 

Larch, family of, 127 

Larch, seed-scales of, 128, 124 

Larch, tufts of leaves of, 76, 67 

Leaves, 64 

Leaves, arrangement as regards 

light, 36, 25, 37, 26 
Leaves, arrangement on stem, 68 



Leaves, compound, 65, 51 
Leaves, form of, 64, 50 
Leaves, " Mosaic," 37 
Leaves, no growth without CO 2 

20 

Leaves, simple, 64, 50 
Leaves, veins of, 67, 55 
Lenticels of, 96, 96 
Life, signs of, 4 
Light, 35 
Light from one side, 35, 23, 36, 

24 
Light, influence on position of 

leaves, 36, 24, 25 
Light, influence on size of leaves, 

38, 2? 
Light, influence of, in formation 

of starch in leaves, 24 
Lime-tree, stem of, 94, 95 
Lime-water, 6, 2, 20, 12 
Linear leaves, 66 
Liverworts, 140, 152 
Louse-wort, 113 



M 

MAGNESIUM sulphate, 15 

Maize, seeds of, 10, 5 

Maize, seedlings of, 10, 5, 13, 8 

Maps of plants, 188 

Marram grass (see Sandgrass), 

166, 145 

Marsh samphire, 1 68, 148 
Mistletoe, 112, 108 
Monkshood, 119, 118 
Monocotyledons, 126 
Moorland, 153, 140, 184 
Moss, 138, 130 
Moss in bogs, 156 
Moss, capsule of, 139, 131 
Moss, spores of, 140 
Movement caused by light, 36, 

24 

Movement of minute plants, 48 
Movement of sensitive plants, 46, 

33, 34, 35 



20O 



INDEX 



Movement of plants in sleep, 46, 

32 
Movement of tendrils, 45, 37 

N 

NASTURTIUM, movement of 

leaves, 36, 24 
Nasturtium, shape of leaves, 65, 

52 
Nasturtium, twining of petioles, 

107, 103 

Needle leaves, 66, 53 
Nepenthes, 117, 115 
Nitrogen, 19 
Nucleus of cells, 92, 97 
Nurse leaves (sec Cotyledons) 



OAK, branching of, 59, 
Orchid, roots of, 57, 41 
Ovate leaves, 65 
Oxygen, 19, 21, 73, 22 



PALM, 57, 42 
Palmate leaves, 66 
Parasites, 109 
Pea-flowers, 86, 80 
Pea-fruits, 87, 81 
Pea-pod (see Pod) 
Pea-tendrils on leaf, 107, 104 
Pea-tendrils t movement of, 45,31 
p eat, 155, 179 
Peltate leaves, 65, 52 

Petals, 80, 121, 127, 122 

Petiole, 64, 50 
Petiole, twining of, 107, 103 
Physical geography, 182 
Pine-cones, 128, 123 
Pine-family, 127 
Pine-leaf, 66, 53 
Pine-seeds, 129, 125 
Pine-seedlings, 129, 126 
Pitcher plants, 117, 1/5 
Plantation of trees, 155 



Pod of pea, 87, 81 
Pollen, 81, 120, 127 
Pollination, 83, 118 
Pollination, arrangements to en- 
sure cross-, 120, 120 
Pond-maps, see Lake 
Ponds, 159, PI. V. 185, 154, 155 
Poppy, PL II. 
Poppy capsule, 89, #5 
Pores giving off water vapour, 31 
Pores in stems, 96 
Potassium iodide, n 
Potassium nitrate, 15 
Potato, starch in, n 
Potato, underground stem of, 61, 

P 

Primrose flower, 80, 72, 84, 79, 

120, 120 
Prothallium, 135, 729, 139 

R 

RECEPTACLE of flower, 82, 7<5, 78 

Reeds, 162, 144 

Rhizome, 61, 46, 161, 743 

Rice, starch in, n 

Roots, adventitious, 56, 40, 57, 41 

Roots, entrance of water into, 33, 

27, 22 

Roots, forms of, 54 

Root-hairs, 13, #, 15, 9 

Root pressure, 34 

Roots of seedlings, 9 

Roots, stilt-, 57, 42 

Roots, storage in, 55, 38, 56, 39 

Roots, uses of, 53 

Rose, flowers of, 79, 70, 77, 118, 

116 

Rose-leaf, 65, 57 
Rose-seedling, 66, 54 
Runners of strawberries, 63 
Rushes, 162, 144 



SALTS, 14, 17, 27 
Sandgrass (see Marram), 102, 700, 
165, 145 



INDEX 



201 



Sea, 174 

Sea holly, 1 68, 147 
Seaweeds, 143, 134, 135, 173 
Seaweeds, colour in, 176 
Section of pond, 192, 154 
Section of stems, 93, 92 
Seedlings, bean, 10, 6, 40, 2^,29 
Seedlings, grass, 35, 23 
Seedlings, maize, 10, 5, 13, 8 
Seedlings, pine, 129, 126 
Seedlings, rose, 66, 54 
Seeds, 86, 125 

Seeds, bean, 8, 3, 9, 4, 10, 6, 91, 89 
Seeds, dodder, in 
Seeds, larch, 128, 124 
Seeds, maize, 10, 5, 91, 90 
Seeds, mistletoe, 112 
Seeds, pine, 129, 125 
Sensitive plant, 47, 33, 34, 35 
Sepals, 78, 69 

Shore, 165, PL F/., 176, 750 
Skin of leaf, 95 
Skin of seed, 9, 3 
Sleep of plants, 46, 32 
Sodium chloride, 15 
Solomon's Seal, 01, 46 
Speedwell, 80, 73 
Spines of cactus, 62, 99, 97 
Spines of gorse, 102, 99 
Spores, 135, 139, 140, 142 
Stamens, 80, 72, 73, 81, 74 
Starch, n, 12, 21, 23 
Starch formed in leaves by sun- 
light, 24 

Starch stained by iodine, n 
Starch stored underground, 26 
Stellaria, 59, 45 
Stems, 58 
Stems bending again to earth, 63, 

49 

Stems, branching of, 59 

Stems, breathing pores in, 94, 96, 

96 

Stems, fleshy, 62, 48 
Stems, sections of, 93, 92 
Stems, twining, 106, 102, no, 106 
Stems, underground, 61, 46, 47 



Stigma, 83 
Stipules, 64, 50, 51 
Stone-crop, 102, 98 
Strawberry fruit, 90, 88 
Strawberry runners, 63 
Sundew, 114, no, 115, in 
Sunflower, i, 2 
Sunflower stem, 94, 93, 94 
Sunlight, oxygen given off in, 21, 

13 
Sunlight helps to form starch in 

leaves, 25 

Sweet pea flower, 86, 80 
Sweet pea fruit, 87, 81 
Sweet pea leaf and tendrils, 45, 

3i, 7, 61 

Sweet pea seed, 87, 81 
Sycamore, buds of, 75, 66 



TENDRILS, movement of, 45, 31 
Tendrils part of leaf, 70, 71 
Tendrils assist climbing, 107, 104, 

108, 105 
Tissues, 93 
Toadflax, 148, 136 
Toadstool, 142, 133 
Transpiration, 31 
Traveller's Joy, 147 
Tree ferns, 133, PL III. 
Tubers, 61, 47 
Tulip bulb, 77, 68 
Tulip carpels, 82, 77 
Tulip flower, 81, 75 
Tulip stamens, 81, 74 

V 

VARIEGATED leaves, 26, 16 
Veins of leaf, 67, 55, 95 
Vine, 33 
Violet, 84, 79, 119, 118 



W 



WATER, 12, 13 



202 



INDEX 



Water, circulation of, in plant, 

28,34 
Water, entry into plant by roots, 

33> 2 '> 22 
Water given off by leaves, 28, 17, 

30, 18, 19, 20 
Water, protection against loss of, 

99 
Water stream in plants, 28, 34 

Water vapour, 28, 17, 31 



Water-buttercup, 159, 141 
Water-lily leaves, 160 
Water-lily, section of stem of, 93, 

92 

" Water-pipe " cells, 94, 97 
Whorls of leaves, 69, 59 
Whortleberry, 62 
Willow herb, 89, 84 
Wind, 154 
Wood-sorrel, sleep of, 46, 32 



THE NATURAL HISTORY OF PLANTS 

THEIR FORMS, GROWTH, REPRODUCTION, AND DISTRIBUTION 

FROM THE GERMAN OF THE LATE 

ANTON KEENER VON JMARILAUN 

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TRANSLATED BY F. W. OLIVER, M.A., D.Sc. 

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