Returning to the seeds that were sown under the soil, we find they

have germinated; the radicle is pushing downwards, and just above the

soil-level we may see the short curved _tigellum_. This very quickly

straightens itself, and then we observe that the cotyledons have been

drawn out of the seed-coats and are displayed as two green leaves,

which in a few days will be an inch or two above the ground, owing

to the growth of the _tigellum_. Here we get quite a departure from

the bean seed, whose cotyledons were _hypogean_ (under the earth),

those of the mustard being _epigean_ (upon the earth). There is also

another point of difference; the mustard cotyledons are green, they

contain chlorophyll corpuscles, have stomates, and so can perform

all the functions of the normal green leaf; thus they help at once

to feed the young plantlet by decomposing the carbon-dioxide of the

air and forming starch, whilst in contrast to this we learnt that the

seed-leaves of the bean were storehouses only. We are now sufficiently

acquainted with the functions of the seed to be able to appreciate the

variations of the _testa_, or seed-coat. In numerous instances the

spines, prickles, hairs, and other growths on the surface have, in

addition to their use in dispersing the seed, an essential purpose in

holding the seed in its rightful position. We will take cress as our

next example, since it may be regarded as a type of all smooth seeds.

Cress seed remains intact until water comes in contact with it; then it

becomes slimy by the liberation of a mucilaginous cement from the outer

coat layer; this is, of course, highly adhesive, and thus the seeds are

fixed firmly into the soil.

Another example is that of the little epiphyte (mentioned in our first

chapter), _Tillandsia usneoides_, or old man’s beard. When the seeds

leave the capsule they are furnished with silky hairs, which enable

the tiny little structures to float through the air; they soon come in

contact with the bark of trees, and then the little hairs cling to

the rough surface. In this position the seeds germinate, and are held

firmly in their place by the tightly-clasping silken strands.

[Illustration: BEECH COTYLEDONS.]

Hardly any pursuit is more delightful than the collecting and drying

of seedling trees; a ramble through the woods in early summer will

reveal many specimens under or near the outskirts of the foliage.

Under the beeches we shall soon light upon the nuts of last year

coming up through the moist, rotting soil, in the form of two broad,

green seed-leaves. As they often retain the dry, three-cornered

seed-husk upon them, we can easily see that they are young beeches;

otherwise, the cotyledon leaves being so unlike the perfect form, it

might be rather difficult to distinguish the species. These seedlings

have germinated somewhat like the bean seed, the radicle has grown

downward, and the curved _tigellum_, pushing upwards, has drawn the

cotyledons out of the seed-coat. We may notice with surprise through

how small an aperture the cotyledons have been pushed, and still they

are uninjured, a fact that is due to their being folded up like a fan

in the seed-husk. As soon as the _tigellum_ reaches light and air it

straightens out, and the flat seed leaves, which are at first of the

palest green, soon deepen in colour, and are working away preparing

food for the growth of the young plumule which springs up from between

the cotyledons, crowned with two perfect young beech-leaves. This

is all the baby-tree can do the first year. We can distinguish the

second-year seedlings by their woody stem, brown leaf-scales, and

silken-fringed young beech-leaves.

[Illustration: ACORN.]

We shall not find cotyledons on the young oak, horse-chestnut, or

sweet-chestnut seedlings, because these remain normally below the

ground (hypogean), forming a storehouse of nutriment for the young

tree. It is interesting to watch the growth of an acorn when placed in

damp moss in a saucer. After a few weeks the acorn will have absorbed

water, and the leathery seed-coat will burst at the pointed end;

through this rent the radicle will protrude, fibres will be found

growing upon the root, the _tigellum_ is thick, and just where the

stalks of the cotyledons are joined to it the plumule emerges as from

a sheath. The plumule is in no hurry to develop leaves; its first

growth is provided for by the rich supply of food within the acorn.

If, however, we look carefully at its little stem, we shall observe

upon its surface a few scattered scales, each with a rudimentary bud in

its axil. When the shoot has attained a height of three or four inches

it develops its first green leaf, and by the end of its first summer

about six will have been formed. A collection of these seedling trees,

carefully dried[24] and neatly arranged in a blank book, with the

English and Latin names to each, a note of the age of the seedling, the

spot where it was obtained, and the date, will in time form a pleasant

memento of forest rambles, and, probably, may lead to further studies

of a similar kind.

[Illustration: HORSE-CHESTNUT.]

[24] They merely need to be placed between sheets of blotting paper,

which should be dried daily and kept in a press or under a weight for a

few days until the specimens are fit to be placed in a book.

To make the collection complete there should be some seedlings of the

other great division of plants, namely, the plants with one seed-leaf

(monocotyledons). A few date-stones will supply these specimens; they

should be sown in moist earth and placed either in a greenhouse or on a

sunny window-ledge, where their growth can be watched.

Their germination is quite different from that of the other seeds we

have described, and if a number of seeds are sown the different stages

can be seen as in the accompanying figure.

One long cotyledon is pushed out from the seed, the free end is like

a sheath. The part nearest the seed forms a structure resembling a

rolled-up stalk; from the former roots are developed, whilst from

the rolled-up stalk or sheath grows the next formed leaf, and each

successive leaf is sheathed like its predecessor. This arrangement can

be well seen in young growing grasses which can be taken to pieces and

examined. I shall conclude this chapter with a brief reference to the

spores or so-called seeds of ferns and mosses.

[Illustration: YOUNG DATE-PALM.]

These are essentially different from the seeds that have formed

our study in the earlier part of this chapter, they do not contain

an embryo. Let us first notice fern-spores, which we shall find in

abundance at the back of maiden-hair and other fern fronds; they are

contained in little brown patches known as spore cases (_sporangium_,

from _spora_, a spore, and _aggeion_, a vessel). If we collect some

of these and sow them on some very fine damp earth, keeping it at the

same time shaded and warm, the spores will soon germinate. We shall

not find a radicle this time as the result of growth, but in its

stead a flat expansion of green tissue (prothallium, Gr. _protos_,

first, _thallos_, a branch) growing upon the earth like an exceedingly

delicate leaf. From the underside of this green film a few very fine

root-like hairs (rhizoids, Gr. _rhiza_, a root) are developed; very

soon with a microscope we shall be able to discern upon the surface of

this structure a few little projections. In one of these is developed

a flask-shaped mass of cells (archegonium, Gr. _archegonos_, first

of a race), in the other (antheridium, diminutive of Gr. _anthera_,

an anther) some minute bodies (antherozoides, Gr. _anthera_ and

_zooid_, a minute life) with tails; these escape from the covering and

wriggle about very much like tiny animalcules until finally they come

into contact with the flask-shaped opening before mentioned. These

tailed structures are something like pollen grains in their function,

only they differ from pollen grains, which are passive, by being

endowed with the power of motion; the result of their fusion with the

flask-like body is to fertilise the germ cell (oospore, Gr. _oon_,

an egg) in that structure, and from the germ cell so fertilised is

developed an embryo from which at once springs the young fern plant.

The first leaf grows from the upper part of the embryo and from the

lower part is developed the “foot,” a little connecting-link between

the green prothallus and the baby fern which serves to nurse the little

plant until two or more leaves have been produced; the roots also grow

from the same part of the embryo. I imagine that fern spores could

be grown and watched through all their various stages even by those

of my readers who dwell in towns, as a bell glass would maintain the

requisite dampness and shelter the young ferns from smoky air.

Lastly I will describe an even simpler form of spore development.

At any season of the year we may find the capsule fruit of mosses

(Calyptra, Gr. _Kaluptra_, a veil), a very common one being the hair

moss (Polytrichum, Gr. _Polutrichos_, having much hair), borne upon

long wiry stalks. Inside the capsule we shall find a large quantity

of small greenish bodies; these are the spores, which of course fall

out when the spore-case is blown by the wind, and being light are

easily carried away and at length find a resting-place in some damp

nook or shady bank. In such a place they find the conditions necessary

for their germination, which is not unlike the same process in other

seeds and spores we have studied. The result is very simple. A fine,

silky, thread-like body (protonema, Gr. _protos_, first, and _nema_,

a thread) is developed; when this has attained a fair size, a little

moss plant begins to grow upon its surface exactly as we see a bud grow

upon a tree-branch, and it is upon this moss plant that the organs of

reproduction are produced. We have now come to the end of our study of

seeds.

An endless source of interest to the student of nature is opened up to

view by carefully observing the beginning of all vegetable life, and

the seed or spore of the commonest weed or fern will teach us lessons

that should ever make us mindful of the wonderful mystery of life and

its genesis.

Objects to collect and examine:—Poppy, silene, and collomia seeds.

Examine _tigellum_ of cyclamen, radish, and carrot. Sow broad beans,

mustard, and cress seed. Collect seedling trees. Sow date-stones.

Examine fern and moss spores.

CHAPTER XII

_THE PHYSIOLOGY OF PLANTS_

“Lo! on each seed, within its tender rind,

Life’s golden threads in endless circles wind;

Maze within maze the lucid webs are roll’d,

And, as they burst, the living flames unfold.”

+Erasmus Darwin+, _The Botanic Garden_.

CHAPTER XII

THE PHYSIOLOGY OF PLANTS

In this chapter I will endeavour to present to my readers a concise

view of the nature and method of the various processes that go on

continually in the growing plant.

These processes were incidentally referred to in our examination of the

character of the various organs of the plant. Thus, in dealing with the

root, we spoke of its physiology so far as concerned the absorption of

water by its root-hairs. In the leaf, we touched upon the correlation

between the shape and arrangement of the leaf tissues and the part

the leaf plays in the economy of the plant. The physiology of the

reproductive organs, again, we briefly explained in connection with

their natural history.

In order to arrange our studies systematically, we may divide the

physiology or function of plants into groups, and, taking each group

separately study their effect on the plant.

We may then divide the functions of plants into

Nutrition,

Assimilation, and

Reproduction.

The first teaches us how a plant feeds and what it feeds upon; the

second, how the food is prepared by the plant so as to enable it to

use this food for growth and to store some of it away for future use.

The third group deals with the various means adopted by plants for

multiplying and increasing the species.

Plants, like animals, must _feed_ and _breathe_ in order to live; the

food of plants, however, differs from that of animals in being more

simple and elementary.

Plant food is of two kinds, water and gas. Water is an actual necessity

to the plant, both as a direct food and as a medium to convey inorganic

food. If we burn some wood to a white ash and then analyse it, six

inorganic elements will always be found—potassium, magnesium, calcium,

iron, phosphorus, and sulphur. These substances have been proved by

experimental water-culture[25] to be indispensable to plant-life;

others are found in larger or smaller quantities, but they are not,

judging by experimental tests, essential to plant life. These inorganic

elements do not enter the plant as such, but in the form of salts

dissolved in water; the phosphorus and sulphur as phosphates and

sulphates. Exactly how these salts and other elements are absorbed will

be best learnt from a simple experiment.

[25] Testing the effect of plant food by water-culture is carried out

in the following manner. Six large jars are filled with distilled

water. In No. 1 all the six elements above mentioned are placed in

small quantities, so as to form a weak solution. In No. 2 only five of

them are added to the water, and in each succeeding jar one element

is left out. A seedling plant which has been germinated on damp sand

is suspended in each jar in such a manner that the leaves are in the

air and the roots in the water without the seed touching the liquid.

The growth of the young plants is carefully observed, and the result

is found to be that No. 1 will grow and flourish, finding all its

needful food in the water, whilst the rest of the seedlings will show

plainly by their feeble and starved condition that, the food elements

being absent, they cannot build up their stems and leaves, and must

eventually perish.

We must first provide a large glass jar three parts full of clear

water. Then a lamp chimney, to the bottom of which a piece of membrane

(which any butcher will supply) has been affixed, should be partly

filled with water coloured by sulphate of copper, and then suspended in

the glass jar. Through a cork fitted to the top of the lamp chimney a

long tube should be inserted. The fluid in the lamp-glass will be seen

to rise in the tube shortly after the experiment is made, and the clean

water in the large jar will become slightly coloured.

[Illustration: TRANSFUSION DIAGRAM.]

This experiment teaches us that liquids have the power of passing

through a membrane; this power is known as diffusion, or _osmosis_.

Further, we notice that the clear fluid passes into the coloured water

more rapidly than the heavy coloured water passes out.

Now the fine _root hairs_ of a growing plant are _membranes_, having

the same property as the membrane we placed on the lamp shade; inside

the root hairs there exists heavy dense cell sap, outside are the films

of hygroscopic water containing (dissolved) inorganic salts, and this

water passes in through the membrane of the root, whilst a very little

of the cell sap passes out into the soil, the quantity passing in being

greatly in excess of that which escapes.

When once the crude water of the soil is inside, it is soon passed

along to the stem and leaves by the pressure of more water coming in,

and by what is called _capillary power_, this power we may easily see

if we dip a fine tube into water, when at once the water will rise up

some distance into the tube. I have pointed out that plant food is

gaseous as well as aqueous.

Oxygen is absorbed by the root very freely from the soil, and,

therefore, farmers and gardeners frequently plough and stir the soil

of fields and gardens so that the roots may obtain a supply of this

needful gas.

Let us now endeavour to see how the gaseous food is taken into the

plant. In order to do so we must remember that the gases necessary

for plant food form part of the air we breathe; this air is made up of

two-thirds nitrogen, one-third oxygen, with a small and varying, but

always present, quantity of carbon-dioxide, and of these the latter is

the most essential to the life of plants.

We have learnt in our study of the leaf how it, by the aid of the green

chlorophyll granules, and under the influence of sunlight, absorbs

this carbon-dioxide and effects certain changes in it. One of the most

essential elements in the growth of plants is _nitrogen_; this we

have just seen constitutes two-thirds of the air we breathe, but the

plant is unable to make use of it in this free form; that is to say,

although the leaf can freely absorb carbon-dioxide it cannot absorb

nitrogen; it has to be taken in by the roots of ordinary plants in the

form of nitrates, that is, in conjunction with some other element.

There is, however, an important exception to this rule; for what are

called the insectivorous plants have the power to absorb nitrogen under

certain conditions. These will be explained in the succeeding chapter.

We can now summarise the processes of nutrition. The roots absorb

water containing earthy salts as well as oxygen gas. The leaves absorb

gaseous food in the form of carbon-dioxide, and I may add sometimes

water vapour. There are two simple experiments that my readers can

make which will prove these statements, and will give them a greater

interest in the somewhat dry details of vegetable physiology. Our first

experiment to show the absorptive power of roots is taken from Sir

Joseph Hooker’s Primer on Botany.

“Take up three plants of the buttercup carefully by the roots; leave

one (No. 1) on the table; place another (No. 2) with its roots in

water; hang the third (No. 3) upside down over a tumbler of water with

a few of the leaves in the water, but the root exposed. In due time No.

1 will have faded; No. 2 will be quite fresh; No. 3 will have the parts

not in the water faded. No. 1 shows that water contained in the plant

has evaporated from its surface; No. 2 that the water has been absorbed

by the root and conveyed to the leaves; No. 3 that the immersed leaves

have not supplied the other portions of the plant with water.”

The second function, assimilation, depends upon several processes

that together go to make up the work of digestion and preparing plant

food. These processes are transpiration, respiration, and evolution

of oxygen; the latter process is associated with the feeding of the

leaf—that is, the absorption of carbon-dioxide. This compound gas

is under the influence of sunlight, and by the agency of the green

colouring granules, decomposed into carbon-monoxide and oxygen; the

latter is eliminated, whilst the carbon and a part of the oxygen is

retained, and with the absorbed water is converted into material that

the plant can use for the purpose of increasing its structure.

By a very simple experiment we can prove the escape of oxygen from the

foliage of plants. A few sprays of such leaves as laurustinus, bay,

arbor vitæ, and maiden-hair fern should be tied firmly to a piece of

stone. We should have ready a soup-plate, a glass shade, and a tub

full of fresh spring water (one large enough to allow the shade to be

held upright under the water). When all is ready, place the bunch of

leaves and stone in the glass shade held horizontally, and gradually

sink it under the water till the shade is quite full; place the

soup-plate at the open end where the shade is, and slowly raise the

glass until it is upright, and then it can be lifted out and placed on

a table in a window where the sun or bright light can reach it. The

bubbles of oxygen will soon begin to form along all the edges of the

leaves and the jewelled effect of the bouquet will be very curious and

beautiful. It is hardly needful to say the stone is simply required to

keep the group in an upright position. By the following day there will

be a large bubble of oxygen collected in the upper part of the shade,

eliminated from the leaves by the aid of chlorophyll and sunlight.

These changes resulting in assimilation are always in correlation with

the process known as _transpiration_. The root is continually taking in

fluids charged with inorganic salts; these are by the water conveyed

to the leaves by means of the network of veins, which we know by the

term fibro-vascular bundles. These, as we may see in skeleton leaves,

traverse the entire substance of the leaves where the salts are used up

in the constructive work of the plant. The water is not all wanted;

part of it passes off in the form of vapour. Transpiration, then, is

the passing off of this water.

[Illustration: SKELETON LEAF.]

We can easily see this process going on if we place a few tropæolum

leaves in a cool tumbler, and then expose the tumbler to sunlight.

In a short time the sides of the glass will show a film of moisture

due to the transpiration of the leaves. This process takes place more

freely in a warm temperature than in cool conditions; consequently, in

hot weather there is rapid transpiration, and as the water is parted

with more cell sap passes into the leaves and stems, and so the plant

is kept cool. We can now see the great use of the little pores known

as _Stomates_; these are found mainly on the under surface, and it is

principally through these pores that the leaf transpires.

We must now carefully note the fact that all growing parts of the

plant take up oxygen and give off carbon-dioxide. This power which is

common to all life is known as _respiration_. It is a process that

cannot be observed in daylight in green plants because this respiration

is feeble, and also because the opposite power of assimilation is

so strong that the action of breathing is obscured. In the absence

of sunlight, however, it can be observed, as also it may be traced

in connection with parts of the plant other than the green leaves.

Seeds, for example, during their earlier growth (germination) give off

carbon-dioxide freely by respiration. This we can prove for ourselves

by taking a large glass jar holding about two or three quarts; fill

this about half full of beans that have been well soaked in water so

as to swell them and induce them to commence germination. Close the

jar with a tight fitting cork; after six or seven hours the presence

of carbon-dioxide may be easily seen. Have ready a small phial of

clear lime water, and with a piece of twine let this down into the jar

without spilling its contents; allow it to remain there some minutes,

keeping at the same time the top closed with a handkerchief. We shall

see that the clear lime water will after a short time become cloudy

or milky; this is due to the carbon-dioxide, liberated by the seeds,

forming chalk with the calcium of the lime water, the chalk being

insoluble and easily seen. Now take out the phial and let it stand,

well covered, when the chalk in the form of a fine precipitate will

be seen at the bottom of the phial. If desired, a second experiment

can be made with the same jar by lowering into it a lighted taper; we

shall find it will go out owing to the presence of the carbon-dioxide;

as this gas does not support combustion our lighted taper is quickly

extinguished.

We can see from these experiments that respiration goes on in the

growing plant and that this process is independent of chlorophyll. It

is an essential part of the life of all plants, and my readers who may

perhaps wonder why it is that two such opposite processes as I have

described are both carried on in the plant must remember that in the

main the feeding process which depends on sunlight and the presence

of chlorophyll is carried on in the _daytime_, whilst respiration is

practically counteracted in the daytime by the vigorous intake of

carbon-dioxide. At night when the rays of light cease and no longer

enable the plant to feed, the respiration is evident. Briefly, we

learn that _in light_ the plant gains in weight, whilst _in darkness_

(by respiration) it loses. The green plant can only construct growing

material out of simple substances in light, having no power to do so in

the dark.

Heat is just as needful to plant-life; it must be above freezing point,

and a somewhat high temperature is necessary to set in motion all those

chemical processes that I have briefly described.

At a low temperature the work of assimilation and other processes

are arrested; on the other hand, a rise in temperature increases the

activity of these processes.

We now come to the third function called reproduction. We have seen

in connection with the food of plants how they convert inorganic

material into organic. This one fact is significant of the great office

of plant-life in nature; animal-life could not exist without its

help. Plant-life may be said to prepare the food of animal-life, and

retain that balance of gases in the atmosphere necessary to healthy

respiration. How important then it is that all kinds of herbs, trees

and plants should multiply and be fruitful, life of any sort is of

limited duration, and subject to all the vicissitudes of accident,

constitution, and climate, and so we find that plants have been endowed

with wonderful powers of reproduction in order that the earth may be

constantly clothed with vegetation, necessary for the life of man and

all animal nature.

By reproduction I want my readers to clearly understand the power

possessed by the individual plant to multiply its kind or species; and

this power is carried into effect in a variety of ways in different

species. These various methods of reproduction then will occupy the

concluding pages of this chapter. The protoplasm (or life principle)

of any individual plant is endowed with the power of giving rise to an

entirely new individual. This is accomplished in one of two ways. In

the first by cells forming a part of the plant, but yet not specially

modified for the purpose of reproduction. This mode of increase

is known as vegetative reproduction. We will illustrate it by two

examples widely apart. Many lowly plants like protococcus (the bright

green substance which so beautifully colours tree trunks in moist

situations) and yeast, are formed of one cell only, and when such cells

attain their full size they simply divide into two or more cells which

grow, and finally attain maturity when the process is repeated.

The other example is that known as the strawberry “runner,” this, as we

know, is only an elongated stem bearing at the end a bunch of leaves,

and from the base of the leaves a few roots, the whole being a new

plant which may be removed from the parent and grown in some other

place.

These, then, are examples of vegetative reproduction, and my readers

can discover for themselves many other instances in the garden.

The plan of propagation by “cuttings” is simply the gardener’s

practical application of vegetative reproduction.

The second mode of increase is by special reproductive cells, which are

set free by the parent plants and become new individuals. The second

mode is common to all plant-life, and in it two distinct processes can

be observed. We often see on a decayed pear or apple a patch of brown

mould (mucor). If we examine it with a lens we see a little forest of

tiny erect stalks, and upon the apex of each is a round ball containing

reproductive cells, each of these, which are called spores (the

spore-case being called the sporangium), contains protoplasm, which is

endowed with the power of giving rise to a new individual mould.

This process is typical of what is common to ferns, and many other

cryptogamic plants, and is called _asexual reproduction_.

The second form is that in which two such spore-like organs as we have

noticed in the mould, fuse together and form a spore capable of giving

rise to a new plant.

This is known as _sexual reproduction_, and is dependent upon the fact

that the protoplasm of either of the two organs is incapable of giving

rise to a new individual plant, and that they must come in contact and

fuse organically before a new plant can be formed. This process of

fusion I have in an earlier chapter described as fertilisation. The

pollen grain, the fertilising agent, is one of the reproductive cells,

and the other, the ovule, is the cell that has to be fertilised. After

this there is the subsequent development of the ovule into the seed,

and in this seed we may recognise a plant in embryo endowed with powers

not possessed by its parent, that enables it to resist extremes of heat

and cold which would result in many cases in death to the parent plant.

By way of experiment some seeds have been subjected to 40 degrees of

cold, and yet have not lost their germinating power, whilst, on the

other hand, it is known that seeds of some plants growing in sandy

deserts lie baking in the sun for many months in a temperature of over

70 degrees, and yet begin to grow as soon as moisture reaches them.[26]

[26] From “Nat. Hist. of Plants,” p. 554: “It has been proved

experimentally that seeds which have been deprived by calcium chloride

of as much water as possible are not killed even at the boiling point

of water.” Careful experiment has shown that there are three stages of

activity in the life and work of a plant—(1) A _minimum or zero_, at

which the processes are just possible; (2) a _medium stage_ or _optimum

point_ where the activity is the greatest; and (3) a _maximum stage of

heat_ where _growth is arrested_. So that we learn that plant-life can

suffer from too high a temperature as well as that which is too low.

Things to be observed or collected:—Experiments to be made in order to

show diffusion, transpiration, and respiration, collection of oxygen

from water bouquet. Carbon-dioxide from germinating beans. Observe—

Blue mould on fruit.

Strawberry runner.

Rooted cuttings.

Stamens and pistil of any flowering plant.

CHAPTER XIII

_INSECTIVOROUS PLANTS_

“Beyond, the moorland has its wealth

Of pink and purple, blue and gold;

Heather and gorse, whose breath gives health,

And ling, a hive of bees that hold:—

And when there’s moisture in the brake,

The clammy sundew’s glistening glands

’Mid carmine foliage boldly make

Slaves of invading insect bands.”

CHAPTER XIII

INSECTIVOROUS PLANTS

The statement in our previous chapter that the leaf has no power to

absorb nitrogen, has to be received with a certain exceptions. These

exceptions are discovered in a large group of plants, having little

or no botanical relationship, and widely separated as regards their

geographical distribution and habit of growth. The term insectivorous

(insect-eating) has been applied to these by eminent botanists who have

studied their habits and mode of growth. We may, as a preliminary to

our study, summarise the main features of these interesting plants,

because I wish my readers to see in them an extension and elaboration

of the various processes we have tried to investigate in plant-life,

and not a mere description of a few vegetable wonders. Rather would I

point out that in studying these deviations from the ordinary type, as

elsewhere, the young botanist should try to arrive at some explanation

of these peculiarities, bearing always in mind that every part of the

plant is created for some special purpose. This train of thought, if

brought to bear upon our botanical study will prevent our regarding the

contrivances of these insectivorous plants as mere freaks of nature,

which appears to me to be a low and unworthy view to take of such

delicate and wonderful structures.

Occasionally, it is true, we meet with monstrosities, in the formation

of which we fail to see any hidden purpose; but even here by careful

observation we shall probably be able to perceive that it is the result

of some injury or the accompaniment of disease from which plant-life is

no more free than animal-life is.

Let us now trace the features that are common to the plants which form

the subject of this chapter.

Perhaps their most interesting function is that of catching and

retaining insects. This is accomplished in various ways, by viscid

fluids which imprison small flies, as in the leaves of the sundew and

other plants; by movements in the leaves, as in the Venus fly-trap; by

a combination of both, as in the butterwort; or by special pitfalls

and traps, as in the pitcher plants, sarracenias, bladderwort, and

cephalotus. Having caught their prey, these plants dissolve it by

means of an acid secretion; the dissolved animal-life is then absorbed

and appropriated for the purposes of vegetable growth. Not all these

processes are carried on by insect-eating plants. In some, for example,

the secretion of dissolving acid is not very apparent, in others the

absorbing glands are not fully developed; but, briefly, the above

features are those possessed by this singular class of plants, and

there is every reason to believe that powers of this kind are more

widely spread than is usually supposed.

We will now notice a few types in detail.

The sundew (_Drosera rotundifolia_) is the pretty and poetic name of a

plant which may often be found on boggy moors. It is barely an inch in

height, a mere rosette of leaves shaped like a battledore, radiating

from a very short root stock, and bearing, in early summer, a central

flower-stalk from four to six inches high, furnished with a few tiny

white flowers. The whole plant lies close to the ground, and is often

embedded in bogmoss, and, were it not for the bright colour of the

leaves[27] and their sparkling dewy effect, it would be a difficult

plant to find. With the naked eye we can see that the leaves are

covered with hairs, and a lens will show still more plainly that these

hairs have each a club-like end bearing a gummy fluid, in appearance

not unlike glycerine. These globules of fluid sparkle in the sun; hence

the name of sundew and the botanical name of _drosera_, from the Greek

“_aroseros_,” or dewy.

[27] On sunny heaths they are often of a rich crimson tint.

[Illustration: SUNDEW.]

Leaves with glandular hairs are not rare amongst our wild plants, and

if this was the only character that the sundew possessed it would not

be specially noticeable. It is, however, the unusual structure and

behaviour of these hairs that claims our notice. The term tentacle is a

not inappropriate one to apply to these “hairs.” A leaf of sundew, with

all its tentacles standing out at different angles from the surface

of the leaf, and each point armed with a drop of viscid fluid, is an

effective arrangement for catching insects. The bright glistening

drops are a fatal attraction to flies, gnats, and other small insects.

When they alight upon the points of the tentacles they soon find that

they are held prisoners. In their efforts to get free they entangle

themselves more and more on the slimy points of the treacherous hairs.

If we watch the tentacles after a fly has been caught, it will soon

be seen that the hairs are bending over and closely pressing down the

wretched captive. This folding over occupies four or five hours from

the time the capture is made. The glands also begin to give out an

increased amount of gummy secretion, and this flow kills the insect

by stopping up its breathing pores, so that literally it dies of

suffocation. The fluid not only increases in quantity, but becomes

acid, and its effect is to dissolve the insect and render it soluble;

the dissolved parts are then absorbed by the glands and digested. This

interesting process can be watched quite easily by carefully taking up

a few plants of sundew with some of the bog-soil and moss in which they

were growing and placing them in a glass dish, where they will continue

for months in perfect health if kept very wet and covered with a bell

glass.

I once lighted on some magnificent sundew growing on boggy land near

Woolmer Forest. Whilst taking up some roots of it I was persistently

attacked by a stinging fly, and, my hands being occupied, I could

not well defend myself. Happily the sundew acted a friendly part! I

was carrying a tuft of it in my hand when, looking down, I saw my

tormenting fly was securely caught upon its leaves. Somehow one always

feels compassion for the unfortunate, and I confess I tried to rescue

the captive, but the creature’s wings and legs were already so glued

together by the viscid dew that it was impossible to release it, and I

realised more than ever how effective the sundew is as a fly-trap.

In transplanting specimens of drosera great care should be taken that

the leaves are untouched, else, being sticky, they will cling together

and lose their delicate beauty. Every few days the plants may be fed,

and happily they are quite willing to accept very minute pieces of raw

beef, so that flies need not be sacrificed in the cause of science. The

little “beafeater” must not be fed a second time until the hairs have

uncurled and the leaf has fully expanded, showing that the last meal

has been digested. I have kept a large pan of sundew in great beauty

for about four months in summer, and when the glass was taken off and

bright sunshine lit up the jewelled leaves the effect was lovely, and a

magnifying glass showed the structure of the leaves and the prismatic

colouring of the dew-tipped hairs.

[Illustration: VENUS FLY-TRAP.]

The Venus fly-trap is an exotic member of the insectivorous family. Its

leaves are remarkably like an ordinary spring rat-trap. A glance at the

drawing will show its formation. On the two lobes of the leaf are a

row of stiff bristles occupying the precise position of the teeth of a

rat-trap. The inner surface of the leaves is of a reddish colour, due

to its being thickly covered with minute red glands; on each lobe there

are three stiff hairs. If a fly alighted on the leaf and walked across

its surface, it would touch one of these hairs, and no matter how light

the touch might be, the hairs are so sensitive they would convey the

signal to the hinge of the lobes, and they would instantly rise up and

clasp the fly, eventually crushing it to death. Then would follow, as

in the case of the sundew, the emission of acrid secretion and the

absorption and digestion of the insect.

Insect-destroying plants are numerous in the vegetable world. They may

be roughly divided into three groups, although there is no strict line

of demarcation between them. First, those like the red lychnis and

others, which, by means of sticky hairs, catch and kill small insects,

an operation that, so far as we know, results in no special good to

the plant. Then there are those, like the sundew, which catch, kill,

and digest the insect for food; whilst the third group consists of

plants which catch and kill insects, but have no digestive process.

Decomposition of the captured insects takes place, but the absorption

which goes on is simply that of the liquid products of decomposition,

the latter process resulting from the insects being immersed in

fluid. To this latter group belong the pitcher plants (_Nepenthes_)

and sarracenias. These last are North American plants of peculiar

structure and appearance. The leaf is folded and modified into a

tunnel-shaped tube differing in form in the various species. In all

there is a kind of cap or lid to the tube, so that rain is kept out. In

one or two species the lid is so arranged that the mouth is exposed.

In the bottom of these tubes there is usually a quantity of somewhat

slimy fluid. The inner face of the lid and surface just inside the rim

of the tube is smooth, usually of a bright shining colour and covered

with minute honey-secreting glands, a most attractive lure for insects.

Below this honeyed surface the character of the sides of the tube

changes completely; for, down to the fluid, it is covered with stiff

hairs all pointing downwards. Now we see how the trap is set. The honey

just inside the tube is attractive, and the insect feeding finds it

very easy to descend the tube; the smooth surface offers no foothold,

and the downward pointed hairs prevent it from returning, until at last

the insect becomes engulfed in the pool of water at the bottom of the

tube. In this fluid insects generally accumulate, decompose, and become

liquid manure.

[Illustration: SARRACENIA FLAVA.]

In Georgia and North Florida these sarracenias are found in the swamps

in large quantities attaining one to two feet in height, their great

tubes half-filled with insects showing their value in tending to

reduce the swarms of flies which abound in such localities. We can

see from these characteristics of the sarracenia a link between the

insect-eating plants which have a true digestive process and ordinary

plants that obtain their food in part direct from the soil. The

sarracenia is simply making an attempt to collect nitrogenous food

by the aid of its form and sweet secretions; thus it lures on flies

and other insects to their doom, which to the plant means an increased

supply of liquid manure for its nourishment.

[Illustration: BLADDERWORT.]

Between the two types of insectivorous plants and ordinary plants there

are endless varieties. The largest known species of “fly-catcher” is

the _Roridula dentata_ of South Africa, which attains a height of six

feet, with leaves similar to the sundew in character. So efficient are

these leaves in catching flies that the Boers hang up branches in their

rooms as fly-traps.

The smallest insect-eating plant is probably the bladderwort

(_Utricularia vulgaris_), a rootless water plant with minute bladders

on small thread-like leaves. The bladders only open inwards, so that

when an insect pushes against the opening or valve it easily enters,

and cannot get out again. The bladder contains water, but the insect

quickly consumes the oxygen in it, and consequently dies, and when

decayed its substance is absorbed by glands on the inner surface of the

bladder.

[Illustration:

PITCHER OF NEPENTHES RAFFLESIANA.

]

Perhaps the most attractive of the group of plants we are considering

is the pitcher plant or Nepenthes. It grows commonly in Borneo and

Ceylon. The pitcher is a direct development of the midrib of the

leaf. It varies in size from the little thimble-like pitcher of

_Nepenthes gracilis_ to the large jug-like receptacles of _Nepenthes

Rafflesiana_[28] and others, each capable of holding nearly a pint of

fluid. The pitchers are furnished with a lid overhanging the mouth of

the receptacle, this is kept open by a thick rim. This rim and the

under-surface of the lid both secrete a sweet fluid which is attractive

to insects, and from the rim and opening of the mouth a smooth surface

directs the ill-fated flies to the sweet sticky fluid always found at

the bottom of the pitcher, out of which they rarely come alive.

[28] See Frontispiece.

Another of our native plants exhibiting these insectivorous habits is

the butterwort (_Pinguicula_). Like the sundew it is a mere rosette of

radical leaves, having upturned margins and a very succulent pellucid

appearance. These leaves are covered with glands which exude a viscid

kind of fluid like that on the tentacles of the sundew. This natural

birdlime catches and holds small flies, midges, and other tiny flying

creatures, as well as crawling insects. The presence of these insects

on the leaf appears to stimulate it to further secretion which must,

of course, lessen the chances of the insect’s escape, and as a further

barrier to prevent its creeping away, the edges of the leaf begin

slowly to curve inwards, so that the caught insect is imprisoned in the

folds of the leaf. The acid secretion which now exudes from the glands

soon dissolves all the nitrogenous and soft parts of the insect, which

are taken up by the absorptive glands of the leaf. There are many other

plants, of which I have not space to make mention, although they are

full of interest, as owing to their curious structure, it is probable

that insectivorous habits might also be ascribed to them. The field

of study is a wide one, and throws much light upon the physiology of

plants as well as the relationship between the plant and animal world.

I would suggest to my young readers, as a practical means of knowing

more of this subject, to try and grow for themselves the sundew,

pinguicula, and sarracenia.

[Illustration: BUTTERWORT.]

The two first can be found, as I have already said, on boggy moors in

England, and the latter plant can be obtained from any florist. All can

be successfully grown in a greenhouse or garden frame, and studying

their growth and habits in this way will teach the young botanist far

more agreeably than learning only from books.

At Kew there is always a fine collection of these insectivorous plants

to be seen in vigorous growth, whilst at the South Kensington Natural

History Museum (Botanical Department) there are some highly interesting

cases illustrating the life history of these remarkable plants.

CHAPTER XIV

_HABIT OF GROWTH IN PLANTS_

“Some clothe the soil that feeds them, far diffused

And lowly creeping, modest and yet fair,

Like virtue, thriving most where little seen;

Some, more aspiring, catch the neighbour shrub

With clasping tendrils, and invest his branch,

Else unadorn’d, with many a gay festoon

And fragrant chaplet, recompensing well

The strength they borrow with the grace they lend.”

+Cowper.+

CHAPTER XIV

HABIT OF GROWTH IN PLANTS

My readers have possibly noticed that in the previous chapters my aim

has been to describe the various organs of a plant, and that I have

tried to show not merely the botanical meaning of the many differences

in the organs of allied species, but to point out also how these

structures are adapted to help the plant to multiply itself. The object

of this final chapter is to take a more general view of plant-life,

and to give some idea of the different habits of plants; how in their

struggle to grow and reproduce themselves they form such habits as tend

to assist them in this effort, and also how entirely, in some cases,

they differ from our ordinary conception of plant-growth.

We have already seen how beautifully plants are adapted to the life

they have to lead, how they are specially fitted to grow in some

particular place and climate, and now I will ask my readers to study

with me certain of the varying habits of plant-life. A typical plant of

an ordinary kind grows, of course, in the earth, produces root, stem,

and leaves, and finally flowers, which are the origin of fruits and

seed; by the latter the plant is again produced, and by this circular

action the continuity of that particular plant is maintained.

Let us now, in imagination, peep into a tropical forest. On its

outskirts we shall see the prototypes of our typical plant; but inside

there are also others of quite a different aspect, and the first to

attract our attention would probably be the curious orchids perched

upon the tree-branches. Their mode of growth differs greatly from that

of a normal plant, for they are merely attached to the branches by

means of clasping rootlets, which do not in any way extract sap from

the tree to which they are clinging.

The moisture they need is collected by the leaves and hanging rootlets

from the humid atmosphere of the forest. These plants that have

acquired a perching habit sometimes grow to an immense size, and where

they do so vegetable _débris_ accumulates about their lower leaves and

roots to such an extent that it serves to supply them with needful food.

[Illustration: PERCHING ORCHID.]

This habit of growth is not confined to the lovely orchids; mosses,

lichens, ferns, and many other plants have acquired a similar mode of

growth, and the various ways by which they attach themselves to the

bearer plants would form an interesting subject of investigation. It

is a not uncommon error to regard these perching plants as parasites,

but this term is properly used for plants which actually feed upon the

branches of the trees where they grow, and of course seriously injure

the trees by so doing. The orchids, on the other hand, do not in any

way injure the branch upon which they rest. Robert Louis Stevenson in

one of his later poems has, with a poet’s license, which in this case

is contrary to fact, described the perching orchid thus—

“For in the groins of branches, lo!

The cancers of the orchid grow.”

This inaccurate observation is, however, more than atoned for by

the wonderful impression Stevenson has given us of the character of

woodland strife, the ceaseless struggle for light and air which goes on

in tropical forests.

In studying the parasites as a group of plants associated by the

same habit of growth, we are led to the conclusion that there is some

difference after all in the morality of plants! Here, for example, we

are confronted with a group of plants that differ entirely from those

we have hitherto examined. The mistletoe, which is the commonest type,

is certainly lower in the social plant-scale than the perching orchid,

the latter with its leaves and rootlets being enabled to earn its own

living, while the mistletoe sends its roots down into the soft sap of

the branch upon which it is growing and—there is no other name for

it—steals its means of living and growing from the substance of the

poor tree upon which it preys. It is true it does, in a half-hearted

kind of way, assimilate a little gaseous food for itself, but the

sickly metallic hue of its leaves is evidence that even in this respect

it is shirking its proper duties of nutrition.

[Illustration: RAFFLESIA ARNOLDII.]

If we desire to study the curious habits of parasitic plants, the two

examples referred to in a previous chapter, the clover-dodder and

the yellow rattle, will afford good examples, the latter plant being

easily obtainable in fields where the pasture is poor and scanty. Very

curious are the modifications and contrivances developed by plants

which have acquired this habit of parasitism, especially amongst such

weird tropical species as _Rafflesia_, a huge parasite growing on the

_Cissus_ in Sumatra. When the leaves and flowers of the cissus have

withered, then here and there a huge knob protrudes from the stem or

root, and this grows in time to an immense stemless flower, measuring

more than three feet across, its cup frequently containing as much as

twelve pints of liquid, and the weight of the whole flower being said

to be about fifteen pounds.

Differing a little in habit from the parasites are the _saprophyte_

plants, which live on decaying vegetation. The little brown leafless

orchid called the bird’s-nest orchis is of this character, as well

as the equally curious coral-root orchis. These plants, as well as

many other parasites, are destitute of chlorophyll, and are therefore

dependent on organic material for food; this they obtain either as we

have seen from living plants or from decaying organic matter. In their

efforts to obtain a needful supply of light and air, some plants assume

climbing habits, using as supports other trees and plants, to the very

obvious disadvantage of the latter. We can well understand how, in a

tropical forest, the weak-climbing plants strive to pass out of the

shaded recesses and force their way to the tops of the slower growing

trees, in order to obtain the share of light, moisture, and air which

are essential to their existence. Very vividly has the late Mr. Louis

Stevenson described such a scene in a tropical forest—

“The hooked liana in his gin

Noosed his reluctant neighbours in;

There the green murderer throve and spread,

Upon his smothering victims fed,

And wantoned on his climbing coil.

Contending roots fought for the soil

Like frighted demons; with despair

Competing branches pushed for air.”

* * * * *

“So hushed the woodland warfare goes

Unceasing; and the silent foes

Grapple and smother, strain and clasp

Without a cry, without a gasp.”

I may explain that the “murderer” alluded to is a species of fig-tree

which, in its early youth climbs up the trunks of other trees, and

by means of its clasping roots so constricts their stems that they

ultimately perish.

In pleasing contrast to this phase of vegetable growth is the habit

which indicates to us something of mutual help and co-operation. In

the _Compositæ_ we find many instances of a habit of growth that bears

distinctly upon this “help-one-another” mode of life. A common daisy

will serve as a type-flower of this kind. The little head is a colony

of flowers, but so close is the association of its individual florets

that it is usual to regard it as one flower rather than a distinct

inflorescence composed of numerous separate and distinct flowers.

In order to understand the mutualism displayed by this little flower,

we must remember that it is an insect-fertilised blossom, and,

therefore, insects must be attracted to it. If we carefully dissect a

flower-head we shall find first a ring of strap-shaped flowers on the

outside, constituting the ray florets—these are imperfect;[29] but

placed side by side on the outer edge they become conspicuous; then we

find in the centre of the flower-head a number of tiny yellow flowers,

each one containing stamens and pistils. What wee things they are, and

if they were developed singly how inconspicuous they would be! When,

however, they are grouped side by side in the centre, and further, when

the outer florets are of a different colour and shape, what a beautiful

and symmetrical whole they make! Truly this is another rendering of

the maxim, Union is strength. From a different point of view the

arrangement is equally interesting. The white and pink tipped florets

of the ray are not capable of bearing seed, and yet we see how they

help those florets that are perfect by their attractive appearance;

then at night or on a cold rainy day these same ray florets bend over

and completely cover up the florets in the centre which are busy

producing seed. My readers will find a rich field of investigation open

before them in studying the flowers of the daisy family, and finding

out for themselves how the florets are grouped together, and to what

extent this principle of co-operation can be traced.[30]

[29] Barren.

[30] A single flower of the Heracleum giganteum would not be specially

noticeable, but when hundreds of them are grouped together in a huge

umbelliferous head they form a most striking object, as may be seen in

the plate. I have often watched the swarms of flies, beetles, and bees

visiting these attractive blossoms on sunny days, and the great umbels

of seed in autumn showed how effectually the insects had carried out

their work of fertilisation.

[Illustration: +GIANT COW-PARSNIP+ (_Heracleum Giganteum_).]

Students will find the corn blue-bottle especially interesting; the

large outer florets contain no organs of reproduction, but still they

are brightly coloured and highly attractive to bees; the inner florets

with their protruding stigmas and anthers, are much smaller; they are

the seed-bearers, and cannot fail to receive pollination when the

bee alights on the flower-head, allured by the showy outer florets,

which apparently exist solely that they may draw insects to visit the

unattractive flowers of the disc.

[Illustration: CORN BLUE-BOTTLE.]

The direct influence of the separate parts of a plant upon one

another, and the very distinct habit of associating together that

they may attain some end such as the visits of insects, leads us to

consider two other aspects of plant-life, both of which are so full

of interest that no botanical work can now be considered complete

without some reference to the matter. If we carefully dig up a clover

plant or a broad bean and examine the little rootlets we shall observe

some small knobs or swellings upon them. These swellings are only

found here and there on some of the roots, so that their presence is

not a normal condition. Placing one of these knobs under a powerful

microscope, we shall find it to be not ordinary root tissue but a

substance teeming with countless numbers of rod-like or rounded atoms

which botanists who have investigated the subject tell us are bacteria,

_i.e._, inconceivably small one-celled plants which are often the

cause of terrible diseases. But some of these mysterious organisms,

on the other hand, are capable of beneficial results. It has of late

been clearly proved that leguminous plants having these colonies of

bacteria on their roots possess the power of assimilating the free

nitrogen that forms such a large proportion of atmospheric air. When

therefore a farmer sows his wheat in a field previously occupied by

clover he finds the clover roots left in the soil contribute the best

possible supply of nitrogen to the wheat crop. This seems a remarkable

fact, since vegetable physiologists have hitherto insisted upon the

fact that plant-life is unable to make use of the free nitrogen of the

air. The other instance of strange habit is that of a symbiosis,[31]

which exists between certain trees on the one hand and the threads of

spawn of some fungi on the other. If the roots of the white poplar are

examined minutely, quite a mantle of whitish threads will be found

covering the growing point. It is said by that eminent botanist,

Professor Kerner, and by others that, as the roots are developed from

the young seedling-tree, they are enclosed in the meshes of the fungus,

and that this particular fungus is always a close associate of the

roots as they grow in all directions. This fact we can see when we

dig up the roots, but the most striking part of the story is this,

that between this fungus root and the roots of the tree there is an

organic connection, a division of labour which results in the tree

receiving from the thread-like filaments of the fungus (_hyphæ_) both

moisture and certain food stuffs from the ground, whilst the fungus

gets in return such organic food as the tree has produced by means of

its green leaves. Such cases as these present to us a manner of growth

that is akin to social habit, and, strange as the union may appear, the

circumstance is by no means uncommon in the vegetable kingdom. Stranger

still perhaps is the union that is sometimes to be found between plants

and some member of the animal world, of which union I shall give an

example. On one of the larger species of sea-anemones (_Anthea cereus_)

are small yellowish spots, which at one time were supposed to form

part of the animal itself. But now the spots turn out to be vegetable

cells, which can be isolated and induced to continue growing after

the death of the anemone. The yellow spots are small algæ, and are

furnished with chlorophyll. We must not regard the algæ as parasites

on the sea-anemone, because they split up the carbon-dioxide under the

influence of sunlight, and by so doing supply the anemone with oxygen

for respiration, whilst the starch formed in the protoplasm of the algæ

passes by diffusion into the anatomy of the animal. The transaction

does not end here; the algæ in all probability receives nitrogenous

substances in return, so that there is a mutual interchange.

[31] A word meaning two plants living together and deriving mutual

benefit.

These are but one or two of the many wonderful phases of vegetable

life, and I hope by thus briefly sketching a few of them my readers

will be stimulated into a greater desire to explore God’s marvellous

works in nature. There is an endless succession of such wonders to be

investigated, but in order to find them we need a careful spirit of

observation, passing nothing by without trying to learn something of

its life history. Every hedgerow is full of delightful problems which

will reward the interested student. A single field has been found to

contain as many as fifty different species of plants, and every month

of the year will present a new aspect of life. In the early spring we

have the germinating seed and the tiny growing moss. A little later the

opening buds with their wealth of interesting points to study, then the

unfolding of the leaves and the gradual development of the flower.

Here and there a climbing plant will engage our attention, its mode of

climbing, its modification of part or parts to enable it successfully

to overcome difficulties, its acceptance of help by the way—as in the

case of a bryony tendril I once came across which cleverly attached

itself to a minute hole in a laurel leaf—these and many other items

will interest us in our walks if we keep our eyes open.

[Illustration: BRYONY TENDRIL.]

Then, as summer slowly passes away and autumn approaches, the fruits

will engage our attention; their forms and shapes and modes of

dispersion will afford ample subjects for study.

[Illustration: TRICHIA THROWING OUT SPORES.]

Winter, too, still brings its store of pleasure for the young botanist.

Nature is not dead—she only sleeps. Nay, unless there is hard frost and

deep snow the field for observation is just as wide and the harvest

as plentiful as at any other season. Look on the old apple-trees and

see what a host of tiny plantlets there is there to glean. Here are

pale-green bearded moss and lichens, there a branch, perhaps, lies

on the ground dead and decaying, under whose mouldering bark, if we

have keen eyes, we may discover tiny tufts of the _Mycetozoa_, whose

capsules, under the microscope (and in some cases even with the naked

eye) are seen to give off clouds of spores, actually thrown out by the

active movements of fine waving threads, a sight never to be forgotten

when it has been watched under favourable circumstances. Winter is

also rich in its harvest of mushroom-like fungi; these will well repay

a little study. We shall be led to note their form, colour, mode, and

habit of growth, how they affect certain trees and soils, and the

important difference of some kinds being eatable and others virulently

poisonous; the mere book student can know very little of the keen

pleasure enjoyed by those who thus think about what they see, and are

ever adding to their stock of knowledge by personal observation. I may

close with some true and beautiful thoughts by one[32] who is herself a

reverent student of the book of nature.

[32] Miss Blanche Atkinson, member of the Barmouth Branch of the

Selborne Society.

“No pleasure is more sure and none less costly than that of watching

day by day the signs of the coming spring; than the delight of seeing

unexpectedly the first primrose, and of finding that the anemones

and hyacinths are pushing their way to the sunshine. Year by year the

miracle of springtime, when the green leaves are shaken forth from the

hard bud is more miraculous. Summer after summer the lilies are fairer,

the wild roses more exquisite, and on through the seasons the varying

pleasures succeed one another. These things never pall; and if the time

should come when we can no longer go out to the hills and woods to

welcome the spring and revel in the bounty of summer we know that the

past is not lost. The fair remembrance of the flowers of the field is

safe in our hearts, and will ‘flash upon that inward eye which is the

bliss of solitude.’”

_GLOSSARY OF SCIENTIFIC WORDS USED IN THIS VOLUME_

GLOSSARY.

A clear definition of scientific terms involves an exact knowledge

of several languages, and when translated into technical phraseology

these definitions often appear to me to be as difficult to a simple

comprehension as the original words they purport to explain.

I have endeavoured therefore, in this glossary, to put scientific terms

into plain words as clearly as was consistent with the facts, and not

by any means to attempt a really exhaustive scientific definition.

A

_Absciss_—A term applied to a layer of separating cells.

_Absorption_—Taking in food by diffusion.

_Accessory_—Anything additional.

_Acetic_—Applied to an acid, sour.

_Achene_—A small dry indehiscent fruit with a leathery coat.

_Adaptation_—As applied to plant-life meaning the structure of the

plant becoming most fitted to its environment.

_Adventitious_—Not developed in regular order.

_Aerial_—Inhabiting or existing in the air.

_Æstivation_—The arrangement of the parts of the flower in the bud.

_Albumen_—Reserve material contained in the seed, analogous to the

white of an egg.

_Alchemilla_—A genus of rosaceous plants with small green flowers.

_Allium_—The onion genus.

_Altitude_—Height.

_Ampelopsis_—A genus of climbing plants allied to the vine whose leaves

are brilliantly coloured in autumn.

_Anemophilous_—Pollinated by the wind.

_Animalcule_—Microscopic insect life.

_Annual_—A plant whose duration of life is one season: _Ex._ mignonette.

_Anthea_—A genus of sea-anemones.

_Anther_—The dilated end of the stamen in which the pollen grains are

developed.

_Antheridium_—The case containing the antherozoids in cryptogamic

plants.

_Antherozoides_—The male cell, or active member in fertilisation of

cryptogams.

_Antirrhinum_—The snap-dragon genus.

_Antiseptic_—Counteracting decay or putrefaction.

_Apocarpous_—Applied to the pistil when the carpels are distinct or

when the pistil consists of one carpel.

_Appendages_—Something hanging or appended, extra.

_Aquatic_—Relating to water.

_Araucaria_—The generic name of the monkey-puzzle tree.

_Archegonium_—The flask-shaped organ containing the female cell in the

cryptogams.

_Arid_—Dry and waterless.

_Arillus_—An out-growth from the funicle (or seed-coat).

_Aristolochia_—A genus of climbing plants with curious “prison” flowers

which attract and retain insects.

_Arum_—A genus of poisonous plants with an inflorescence consisting of

spadix and spathe.

_Asexual_—Not sexual.

_Asparagus_—A genus of edible vegetables and climbing plants.

_Assimilation_—The conversion of crude food into protoplasm.

_Aster_—The generic name of the Michaelmas daisies.

_Avena_—The generic name of the oat.

_Awn_—The beard of barley and other corn.

_Axillary_—Growing in the axil of the leaf.

B

_Bacteria_—Minute one-celled living atoms, the cause of most contagious

diseases.

_Bamboo_—A giant grass.

_Banana_—The fruit of the genus Musa.

_Bark_—The rough external part of a stem.

_Barm_—Same as yeast.

_Bast_—The fibrous tissue between the bark and the wood of a

dicotyledonous stem.

_Begonia_—A genus of plants with bright flowers and oblique or

one-sided leaves.

_Betula_—Generic name of the birch-tree.

_Biennial_—A plant whose duration of life is two seasons: _Ex._

Beetroot.

_Bifacial_—With upper and lower sides structurally different: _Ex._

laurel leaf.

_Bignonia_—A genus of flowering climbing plants.

_Blade_—The broad part of the leaf.

_Bougainvillia_—A genus of climbing tropical plants with bright pink

bracts and small yellowish flowers.

_Bulb_—A dormant bud surrounded with fleshy scales.

_Bulbils_—Small bulbs.

_Bunium_—A genus of tuberous Umbelliferæ, earthnut.

_Buoyant_—Light, able to float in air or water.

_Button-wood_—A term applied in America to the plane tree.

C

_Cacti_—A family of succulent plants usually devoid of leaves.

_Caducous_—Quickly dropping off.

_Calceolaria_—A genus of herbaceous garden plants with pouched flowers.

_Calcium_—An element present in all calcareous rocks.

_Calyptra_—The hood of a moss-fruit.

_Calyx_—The outer whorl of the flower or floral envelope, cup-shaped.

_Cambium-layer_—A layer of active growing tissue.

_Campanula_—A genus of Alpine and herbaceous plants with bell-shaped

flowers.

_Camphor_—A drug obtained by dry distillation of the leaves and stems

of Camphora officinarum.

_Capillary_—Fine and minute, hair-like.

_Carbon-dioxide_—Symbol CO₂. A gas existing in small quantities in

the air, otherwise called carbonic-acid gas.

_Carbon-monoxide_—A poisonous gas whose molecule is composed of one

atom of carbon and one atom of oxygen.

_Carex_—A genus of sedge-like plants.

_Carpel_—A pistillate leaf, one of the component parts of the pistil.

_Caterpillar_—The form of an insect after it is hatched, first stage.

_Catkin_—A spike of staminate or pistillate flowers usually pendulous.

_Checkered_—Outlined into a square-like pattern.

_Chevaux de frise_—An obstacle consisting of iron spikes set in a

framework of iron.

_Chlorophyll_—The green colouring matter of leaves and stems.

_Cholera_—A contagious disease.

_Chrysalis_—_pl._ Chrysalides. The form assumed by some insects before

they reach the winged state.

_Chrysanthemum_—A genus of showy flowering plants belonging to the

Compositæ.

_Cinchona_—A genus of trees yielding quinine.

_Circumnutation_—The rotating motion made by the growing point of the

stem and leaf.

_Cissus_—A genus of vine-like plants often with brilliant coloured

leaves.

_Climatic_—Influenced by a climate.

_Coalesce_—To fuse, cohering of parts not usually joined.

_Cocos-de-mer_—The large double cocoa-nut tree of the Seychelles Isles.

_Collomia_—A genus of plants whose seeds are remarkable for the spiral

fibres which expand elastically when wetted.

_Compositæ_—A group of plants having an inflorescence of florets

arranged upon a common receptacle or head.

_Concentric_—A number of rings having a common centre.

_Cone_—The hard woody fruits of the fir-tree.

_Coniferous_—Fir-like, or cone-like; belonging to the cone-bearing

family.

_Continuity_—Unbroken succession.

_Corolla_—The second whorl of the floral envelope usually brightly

coloured.

_Corpuscles_—Grains or granular.

_Correlation_—_i.e._, connection, interdependence.

_Cortex_—The bark or outer covering of stems.

_Cotyledon_—A seed leaf.

_Cruciferæ_—A group of plants having their petals arranged crosswise,

with six stamens two of which are longer than the others.

_Cryptogamic_—Relating to flowerless plants.

_Culm_—The straw-like stems of the grasses.

_Cuscuta_—The dodder genus, parasitic upon flax and clovers, &c.

_Cuticle_—The exterior and thickened part of the epidermis.

_Cyclamen_—Dwarf primulaceous plants with shortened stems (corms).

D

_Dahlia_—A genus of tuberous-rooted plants.

_Darlingtonia_—A genus of Californian plants related to the side-saddle

plants.

_Datura_—The generic name of the thorn-apple.

_Débris_—Remains, rubbish.

_Deciduous_—Applied to plants, the leaves of which fall off in autumn.

_Dehiscent_—Splitting open when ripe.

_Deodar_—A tree allied to the cedar of Lebanon.

_Dentaria_—A cruciferous plant bearing bulbils in the axils of the

leaves.

_Diagrammatic_—Drawn to illustrate a statement.

_Dicotyledon_—A plant whose embryo has two primary seed-leaves.

_Diffusion_—The intermingling of fluids (gases or liquids).

_Diœcious_—When the pistillate flowers and staminate flowers are borne

upon separate plants of the same species.

_Dispersion_—Scattering.

_Drosera_—The generic name of the sundews.

E

_Elastic_—Springy.

_Embryo_—The future plant contained in the substance of the seed.

_Embryo-sac_—The cavity in the substance of the nucellus, containing

the egg-cell, which after fertilisation becomes the embryo.

_Endocarp_—The inside layer of the pericarp.

_Entomophilous_—Pollinated by insects.

_Epicarp_—The outside layer of the pericarp.

_Epidermis_—A layer of generally flattened cells forming the skin of

the plant.

_Epigean_—Developed like the cotyledons of mustard, above ground.

_Epipetalous_—Growing upon the petals.

_Erysipelas_—A disease of the blood causing a red eruption.

_Eucalyptus_—The generic name of the Australian blue gum tree.

_Euonomin_—A dry extract made from the root-bark of Euonymus

altro-purpureus, a North American shrub.

_Euonymus_—A genus of shrubs and hedgerow trees.

_Euphorbia_—The spurge genus.

_Exogen_—Growing by addition to outside of wood and inside of bark,

synonymous with dicotyledon.

F

_Fermentation_—Changes that take place in wort when barm or yeast is

added, or when fluids are exposed to the air. _See_ Yeast.

_Fertilised_—Completion of the act of fertilisation, _i.e._, fusion of

the male element contained in the pollen tube with the egg cell of the

ovule.

_Fibrous_—Meaning a structure of fine loose filaments or hairs, _i.e._,

young rootlets.

_Fibro-vascular_—A compound tissue of fibres and vessels.

_Filament_—A thread-like fibre.

_Flaccid_—Want of firmness, soft and lax.

_Fructification_—The fruit system of a plant.

_Fuchsia_—A genus of exotic flowering plants having a petaloid calyx.

_Function_—As applied to plant-life, meaning the use and lifework of

the members of a plant.

_Fungoid_—Growth like a fungus.

G

_Gamopetalous_—Petals united.

_Gamosepalous_—Sepals united.

_Genesis_—Creation, production.

_Germinate_—The change of the seed from the dormant state to the active

growing stage.

_Gloxinia_—A genus of popular hothouse plants with large handsome

flowers.

H

_Habitat_—The natural abode of a plant.

_Herbaceous_—Applied to plants which do not form a hard woody stem.

_Herbarium_—A collection of dried plants.

_Hexagonal_—A six-sided and angled figure.

_Hibernating_—Sleeping, a dormant condition.

_Hilum_—The black scar on a bean seed.

_Hippuris_—A genus of aquatic flowering plants.

_Horizontal_—Parallel to the horizon level.

_Hoya_—A genus of tropical climbing plants.

_Hyacinths_—Bulbous plants.

_Hydrangea_—A genus of flowering shrubs.

_Hygienic_—Relating to the preservation of health.

_Hygrometric_—Moisture and its influence.

_Hygroscopic_—Applied to the film of water surrounding the particles of

the soil.

_Hypericum_—The generic name of the St. John’s wort.

_Hyphæ_—Filaments or threads of the fungus spawn.

_Hypogean_—Development of the cotyledons under ground.

I

_Impatiens_—The generic name of the balsam.

_Impervious_—Not to be penetrated by water.

_Insectivorous_—Catching and killing insects, plants that have this

power and can absorb the decomposed insects.

_Insoluble_—Substances that do not dissolve in water.

_Intercellular_—Spaces between the cells.

_Internode_—The space between two nodes.

_Involucre_—A whorl of bracts.

_Iodine_—A soluble substance extracted from kelp and used as a test for

starch.

L

_Laburnum_—Yellow-flowered trees allied to the Pea family (Leguminosæ).

_Legume_—The dehiscent fruit of the pea family, a pod.

_Leguminosæ_—A family of plants having for their fruit a legume or pod,

_i.e._, Pea, Laburnum.

_Lenticels_—Minute pores in the bark.

_Liane_—A hanging root or stem.

_Liber_—The inner bark, same as phloëm.

_Linnæa_—A genus of dwarf trailing plants.

_Luscious_—Sweet and succulent.

M

_Magnesium_—The metallic base of magnesia.

_Magnolia_—A genus of flowering shrubs and trees.

_Mahonia_—A genus of evergreen shrubs belonging to the barberry family.

_Martynia_—A genus of plants having capsules with long curved hooks.

_Melampyrum_—A genus of dwarf flowering plants partly parasitic.

_Membranous_—Thin and destitute of green colour usually applied to

bracts.

_Mesocarp_—The central layer of the pericarp.

_Mesophyll_—The ground tissue of the leaf.

_Metabolism_—Changes which take place in protoplasm and which it causes

in other substances.

_Microbes_—A term applied to one-celled plant atoms, like bacteria.

_Micropyle_—A small pore in the coats of the ovule through which the

pollen tube passes.

_Modicum_—Moderate sized; a small quantity.

_Monocotyledon_—A plant whose seed is furnished with one seed leaf.

_Monœcious_—Applied to a plant when the stamens and pistil are in

distinct flowers.

_Monstera_—A genus of climbing aroids with edible fruit.

_Mucilaginous_—Sticky, gumlike, secreting mucilage.

_Mucuna_—A genus of Brazilian Leguminosæ, yielding the cowage

(consisting of intensely irritating hairs), of the Materia Medica.

_Mutualism_—Interchange of some advantage, botanically applied to the

union of two dissimilar plants which live in _close_ contact with each

other to their mutual benefit.

_Mycelium_—The root-like colourless filaments of fungi.

_Mycetozoa_—A term applied to the slime-fungi.

N

_Nectary_—A honey secreting gland or spur.

_Nemophila_—A genus of dwarf annual flowering plants.

_Nepenthes_—A genus of plants having as a prolongation of the midrib of

the leaves, ascidia or pitchers.

_Nocturnal_—Happening by night.

_Node_—The exact point on the stem from which the leaf is developed.

_Normal_—Regular, unaffected by any modification.

_Noxious_—Hurtful or poisonous.

_Nucellus_—The internal tissue of the ovule within which the embryo-sac

is embedded.

_Nutrition_—The process and function of taking in food for the purpose

of growth and to replace waste.

O

_Orchis_—A genus of the orchid family growing in the soil.

_Osmosis_—The passage of fluids through a membrane.

_Ovary_—The ovule case, that part of the carpel that bears ovules.

_Ovule_—The structure which after fertilisation forms the seed.

_Ovum_—The egg cell of the ovule.

_Oxalis_—The generic name of the wood sorrel.

_Oxygen_—A gas, one of the constituents of the atmosphere.

P

_Palisade-tissue_—A tissue of oblong cells placed side by side at right

angles to the flat surface of the leaf.

_Papilionaceous_—Butterfly shaped.

_Pappus_—A light hairy development from the calyx of some plants.

_Parasitic_—The habit of growing upon and deriving nourishment from

another plant.

_Pellucid_—Shining and transparent.

_Perennial_—Plants that live for an indefinite period.

_Perianth_—A term used when there is no distinction between calyx and

corolla.

_Pericarp_—The ripened walls of the ovary constituting the structure of

the fruit.

_Persistent_—Applied to the parts of the flower that remain on for some

time.

_Petunia_—A genus of Brazilian Solanaceæ.

_Philodendron_—A genus of aroids usually climbers.

_Phleum_—A grass.

_Phloëm_—The inner bark, containing sieve-tubes.

_Phosphate_—A salt formed by the union of phosphoric acid with some

base.

_Phyllotaxis_—The law of leaf arrangement.

_Physalis_—The generic name of the winter cherry.

_Physiological_—Having reference to the function or life work of the

plant.

_Picea_—A genus of the Conifer family.

_Pinetum_—A garden devoted to the culture of pine-trees.

_Pinguicula_—The generic name of the butterworts.

_Pinus_—A genus of the Conifer family.

_Pistil_—The female part of the flower consisting of ovary, style, and

stigma.

_Pistillate_—Applied to flowers having the pistil only.

_Pith_—The soft tissue in the centre of the stem.

_Plumbago_—The generic name of the leadworts, small flowering plants

and shrubs.

_Plumule_—The first stem shoot of the germinating seed.

_Poa_—A grass.

_Poinsettia_—A genus of Mexican plants having bright scarlet bracts and

small flowers.

_Pollard_—A tree trunk with its branches cut short.

_Pollen_—The fertilising or male part of the flower.

_Pollination_—The act of conveying the pollen from the stamen to the

stigma.

_Polypetalous_—Separate or many petals.

_Polysepalous_—Separate or many sepals.

_Polytrichum_—The generic name of the hair moss.

_Potassium_—The metallic base of potash.

_Proboscis_—The feeling and feeding organ of an insect.

_Prothallus_—The first growth when the spore of a fern germinates.

_Protococcus_—A genus of unicellular plants forming a green stain upon

trees, &c.

_Protonema_—The first growth of the moss-spore.

_Protoplasm_—A highly complex substance forming the essential part of

all living cells, and to which all life growth is due.

_Prototypes_—First forms of plant-life.

_Psamma_—A genus of the grass family.

_Pseudo-bulb_—A swollen stem common in the epiphytic orchids.

_Pteris_—The generic name of the bracken fern.

Q

_Quiescent_—Inactive, dormant.

_Quinine_—An alkaloid extracted from the cinchona trees.

R

_Radicle_—The first formed root when a seed germinates.

_Rafflesia_—A genus of brown leafless parasites.

_Receptacle_—That part of the stalk on which the flower is developed.

_Resin_—A secretion from certain trees which hardens on exposure.

_Respiration_—The process of breathing.

_Rhinanthus_—The generic name of the yellow-rattle (a root parasite).

_Rhododendron_—A genus of popular flowering shrubs and dwarf trees.

_Root-cap_—A loose covering of tissue that protects the extreme point

of the growing root.

_Root-hairs_—The delicate unicellular hairs found on the young root.

S

_Salicine_—A substance obtained from the bark of willows, soluble in

water and alcohol, and crystallising in bright white needles.

_Salvia_—A genus of labiate plants.

_Samara_—Winged fruit.

_Saprophyte_—Plants that live upon decaying organic matter.

_Sarracenia_—The generic name of the North American side-saddle plants.

_Saxifraga_—A genus of dwarf Alpine plants.

_Scales_—Rudimentary leaves.

_Secretion_—Applied to substances like resin and honey, the production

of assimilation and metabolism.

_Sedum_—A genus of succulent Alpine plants.

_Soluble_—Any substance that dissolves in water.

_Spadix_—The inflorescence of the Aroideæ.

_Spathe_—The bract of the Aroideæ.

_Sporangium_—The spore-case of some of the cryptogamia.

_Spurious_—False.

_Stapelia_—A genus of succulent plants, very poisonous and fœtid.

_Starch_—Colourless grains, a product of assimilation in the leaf.

_Stigma_—The receptive part of the pistil.

_Stipa_—A genus of the grass family.

_Stipules_—Small outgrowths at the base of the petiole.

_Stomata_—Minute pores in the epidermis of the leaf or green stem.

_Sulphate_—A salt formed by the combination of sulphuric acid with some

base.

_Sycamore_—The plane tree of Scotland, Acer pseudoplatanus.

_Symbiosis_—Mutualism, a living for one another, interchange of

benefits by united growth.

_Syncarpous_—United carpels.

T

_Tannin_—A substance widely diffused through the leaves and stems of

plants, of an astringent character.

_Tap-root_—A root that forms an unbranched tapering axis: _Ex._, carrot.

_Tendril_—A coiled or hooked filament modified to assist plants to

climb.

_Tentacles_—The glandular and feeler-like hairs of the sundew.

_Terminal_—At the apex or end.

_Testa_—The skin of seed.

_Tigellum_—The first stalk of the seed bearing the cotyledons.

_Tillandsia_—A New World genus of perching or epiphytic plants.

_Tissue_—A group of cells; having a common origin.

_Tormentilla_—A genus of small creeping rosaceous plants.

_Transpiration_—The giving off of water vapour from the surface of

leaves and stems.

_Tricyrtis_—The generic name of the toad-lily.

_Tuber_—A fleshy root or succulent underground stem.

U

_Umbelliferæ_—A group of plants having an umbellate arrangement of the

inflorescence or flower-head.

V

_Vallisneria_—A genus of aquatic flowering plants.

_Valved_—Having valves, _e.g._, anther of the barberry.

_Vapour_—Gas into which most liquids and solids are converted by heat.

_Vasculum_—A little vessel or box for collecting botanical and other

specimens.

_Venation_—The arrangement of veins in a leaf.

W

_Weigelia_—A genus of flowering shrubs allied to Honeysuckle.

_Whorl_—An arrangement of leaves or parts of the flower in rings.

_Wort_—Sweet unfermented new beer.

Y

_Yeast_—A unicellular plant that sets up fermentation under certain

conditions.

The Gresham Press,

UNWIN BROTHERS,

WOKING AND LONDON.

Transcriber’s notes

The text contains some inconsistencies in the usage of hyphens. Only

those have been corrected where the majority was spelled otherwise. All

corrections made are listed below.

To represent formatting the following conventions are used:

_word_ means that “word” is in italics;

+word+ means that “word” is in small capitals;

=word= means that “word” is in bold.

The asterism (⁂) on page 8 should be inverted, but this was not

possible to achieve since no such symbol exists.

Corrections

Page 20 In the list of illustrations hyphens removed from

“MONO-COTYLEDON” and “DI-COTYLEDON”, to match the captions of the

illustrations;

Page 21 In the list of illustrations “WHITE LILY PISTIL” changed

to “WHITE-LILY PISTIL” and “POLLEN-TUBE” changed to “POLLEN TUBE”,

to match the captions of the illustrations;

Page 22 In the list of illustrations “DIAGRAM OF TRANSFUSION” changed

to “TRANSFUSION DIAGRAM”, to match the caption of the illustration;

Page 22 In the list of illustrations “FLAVA” added behind “SARRACENIA”,

to match the caption of the illustration;

Page 42 “Another of these perching-plants is _Tillandsia Usnoides_”

changed to “Another of these perching-plants is _Tillandsia

Usneoides_”;

Page 62 “aërial” in “send down slender aërial roots” changed to

“aerial”, to match the spelling in the rest of the text;

Page 69 In “We may look upon the earth as being a sort of store-house”,

“store-house” changed to “storehouse” to match the spelling in the

rest of the text;

Page 100 In “in a skeleton leaf, the mid-rib”, “mid-rib” changed to

“midrib”, to match the spelling in the rest of the text;

Page 102 one occurrence of “called” removed from “belonging to this

great division are called called dicotyledons”;

Page 136 “to render the bud waterpoof” changed to “to render the bud

waterproof”;

Page 138 In “wood-sorrel is rolled into a spiral”, “wood-sorrel” is

changed to “woodsorrel”, to match the spelling in the rest of the

text;

Page 159 In “resembling the pine-apple plant”, the hyphen is removed

from “pine-apple”, to match the spelling in the rest of the text;

Page 202 “so that at length the seed-coats” changed to “so that at

length the seed-coat”;

Page 223 “PINE CONES” in the caption of the illustration, change to

“PINE-CONES” (in the list of illustrations too) to match the spelling

in the rest of the text and “fir-cones”;

Page 232 “have seeds with wings lightly twisted” changed to “have seeds

with wings slightly twisted”;

Page 238 “COCOS DE MER” in the caption of the illustration is

hyphenated (in the list of illustrations too) to match the spelling

in the rest of the text;

Page 246 “ivy-leafed toadflax” changed to “ivy-leafed toad-flax” to

match the spelling in the rest of the text;

Page 263 “the little epiphyte (mentioned in our first chapter),

_Tillandsia usnoides_” changed to “the little epiphyte (mentioned

in our first chapter), _Tillandsia usneoides_”;

Page 263 “by decomposing the carbon dioxide” changed to “by decomposing

the carbon-dioxide” to match the spelling in the rest of the text;

Page 280 “absorbs this carbon dioxide and effects” changed to “absorbs

this carbon-dioxide and effects” to match the spelling in the rest

of the text;

Page 337 “into technical phraseology these defininition” changed to

“into technical phraseology these definitions”;

Page 340 comma after “tuberous Umbelliferæ, earthnut” changed to

period;

Page 348 period added after “flowering plants and shrubs”.