First book of Indian botany

Preface

This little book is, in substance, my “ Lessons in Elementary Botany ” adapted for use in India.

But in preparing it, I have had in view the want, often felt, of some handy resume of Indian Botany, which might be serviceable not only to residents in India, but also to any one about to proceed thither, desirous of getting some preliminary idea of the Botany of that country.

I might have entitled the book “ Illustrations of Indian Natural Orders of Plants;” but as the same chapters, with necessary alteration, on the Elements of Structural and Physiological Botany are prefixed to the systematic part which I originally drew up for my previous work, the whole thing seems to me tolerably suited to serve as a “ First Book of Indian Botany.”

My chief difficulty has been in the selection of suitable Types to illustrate the Natural Orders on the plan of the late Professor Henslow. In a book for use in Britain there is no difficulty on this head, for so many plants are pretty, uniformly dispersed over our limited area, that nearly every

VI

PREFACE.

Type-species is within reach throughout our islands. But in India the case is very different. Few easily recognisable species have a sufficiently general distribution, or, if they have, it often happens that some exceptional peculiarity of structure unfits thejn for service as typical examples of any group. One consequence of this difficulty is, that I have been obliged to use, in some cases, garden plants which are widely cultivated in India, although not actually indigenous there, in preference to native species. For example, in the large Order Composite I have preferred the Mexican Zinnia , so generally grown in Indian gardens, to any native species ; and the Chinese Dendrobium nobile to any Indian species of the great Orchid Family. This latter is perhaps unfortunate. There are a few wild Indian Orchids with a wide distribution, but they are either difficult of recognition by those not accustomed to botanical pursuits, or unfitted in some other way to serve my purpose. However, in such cases as these I have nearly always introduced cuts, drawn by Mr. Fitch, which I trust may partially substitute the actual specimens, if these be not obtainable.

With regard to the selection of suitable and easily accessible illustrative Types, I shall be glad to receive advice from any one interested in the matter. Perhaps it would be a good plan to introduce two, three, or more species in illustration of the different Orders in cases in v hich the common conspicuous species are restricted in their

PREFACE.

VII geographical range. As to this, I may find reason to modify the book, should it ever get, as I hope it may, into a second edition.

I have never visited India myself. I have, however, under Dr. Hooker’s direction, had much to do with Indian Botany, especially in connexion with the enormous store (about twelve or fourteen large waggon -loads) of dried Indian plants rescued from the cellars of the late East India Company, through the persevering efforts of this distinguished Botanist, which have been arranged and distributed at Kew during the last ten years.

In writing out this little work, I have been greatly indebted to Dr. Hooker, and to Dr. T. Thomson, of Kew, for many useful hints, especially concerning the selection of illustrative Type-species. Dr. Thomson and Mr. Edgeworth have also very kindly given me much help in introducing some local or native names of commoner species ; a matter upon which I have no personal knowledge.

Kew, London, August 1869.

Chapter II

WHAT THE ROOT, STEM, AND LEAVES HAVE TO DO . . . .

CPIAPTER III.

FURTHER DETAIL AS TO THE LEAVES OF THE FLOWER . .

CPIAPTER IV.

COMMON FLOWERS TO COMPARE WITH THE FLOWER OF THE ORANGE

CHAPTER V.

EXAMINATION OF COMMON PLANTS CONTINUED AS BEFORE .

PAGE

I

CONTENTS.

CHAPTER VI.

HOW TO FILL UP THE SCHEDULES . .

CHAPTER VII.

THE VARIOUS ORGANS AND THEIR MODIFICATIONS

CHAPTER VIII.

THE MINUTE STRUCTURE AND VITAL PROCESSES OF PLANTS . Io6

CONTENTS.

xi

PAGE

PART I.

THE ELEMENTS OF STRUCTURAL AND PHYSLOLOGLCAL BOTANY.

Chapter I. Of The Root, Stem, And Leaves

1. The Root. — Its form and general structure : it penetrates the soil;

is colourless; irregularly branched; destitute of leaves; and its extremities are sheathed.

2. The Stem. — It ascends ; is coloured ; bears leaves and branches at

definite points ; the extremities are not sheathed, but give off, successively, rudiments of leaves.

3. Foliage-leaves.— They are borne by the stem only. “Radical”

and “cauline” leaves: thin, coloured green, consisting of a horizontally expanded blade with, or without, a petiole.

4. Flowers consist of leaves. The peduncle. Suppression of inter-

nodes in flowers. The receptacle of the flower.

5. The Sepals ; forming the calyx.

6. The Petals ; forming the corolla.

7. The Stamens ; bearing anthers which contain pollen-grains.

8. The Carpels. Ovary and ovules ; style ; stigma.

9. The ovary persists after the other parts of the flower fall away.

The Fruit ; seed ; embryo and its parts.

IO. A summary of the parts examined.

Gather, first of all, a specimen of any common annual weed. It doSs not signify for our present purpose which you gather, provided it have a branching root, a distinct stem, and stalked leaves. Never mind the flower just at

B

THE ROOT.

[CHAP.

present. In gathering the specimen take it up carefully, so that the root may be uninjured.

Proceed to examine your plant.

i. Observe the Root, noting in what respects it differs from the parts which grow above ground. It consists of numerous fibres, or of a principal central root tapering downwards and giving off irregularly many thread-like fibrils. It is destitute of the green colouring of the stem and foliage, being pale, or nearly white : it bears neither buds nor leaves, and from its direction it appears to have avoided the light.

the tip of one of the root-fibres uninjured, cut it off and examine it minutely with your magnifying glass. In case you have not the means of examining it with a high magnifier, you will find Fig. i a sufficiently correct representation of it, divided through the middle and magnified many times.

The point which I want you particularly to note is this : — The extremity of the fibre is covered by a closely-fitting sheath, protecting the actual growing point, which is hidden immediately within the end of the sheath, to which it is directly joined. This protecting sheath is being constantly renewed at its inner side by the “growing point;” so that as the outer layers become worn or withered by forcing a way through the soil and pebbles, they are constantly replaced by inner layers which take their turn, replace them, and then die, to be in like manner replaced by fresh inner layers derived from the “ growing point ” so long as the root continues to live and to lengthen.

If you can find

Fig. i. Longitudinal section through the extremity of a Root-fibre, magnified. — gp, growing point ; sh, sheath ; rf, root-fibre.

THE STEM.

You will find then that the root avoids the light ; that it is pale or nearly white ; that its fibres give off irregularly numerous delicate thread-like branches (fibrils) ; that it is destitute of buds and leaves, and that the tips of the root are protected by cellular sheaths.

2. Now examine the Stem.

You observe, at once, that the stem rises above the ground, seeking rather than avoiding the light. It may either be firm and erect, or weak and trailing. Unlike the root, it is coloured more or less green, and not being usually woody, we may speak of it as herbaceous. It bears several foliage-leaves arranged on different sides of the stem, the lower ones usually springing in a tuft from its base — at least while the plant is young. The upper foliage-leaves are nearly always arranged singly or in pairs on the stem, although sometimes the only foliage-leaves of annual plants spring in a tuft apparently from the root.

If we examine the growing point of a young stem under a magnifying glass, carefully dissecting away the leaves which surround it, we shall find that to the very apex it continues to give off successively minute lateral prominences, which are the rudiments of leaves, either of foliage-leaves or of flower-leaves, for they both originate upon the stem in the same way, though they soon become different, both in their arrangement, form, texture, and colour. In no case does the stem terminate in a cellular sheath like that which protects the tips of the root.

At the extremity of the principal stem of your plant, if fully grown, or upon certain of its branches, you find a tuft of coloured leaves forming a flower.

The branches spring from points where foliage-leaves are given off from the stem ; each branch occupying the angle (called the axil of the leaf) which the leaf makes with the

FOLIAGE-LEA VES.

[chap.

stem. The branches may either resemble the primary stem from which they are given off, or they may differ in the kind of leaves which they bear, in the length of the intervals between their leaves, or otherwise.

The stem, we find, rises above ground ; it is usually coloured green, and is herbaceous in texture ; it bears foliage-leaves and flowers.

3. Foliage-leaves. — I use the term foliage-leaves at present simply in order to avoid confusion with the leaves of which flowers are composed. It is not necessary you should always call them so, but it is necessary that you thoroughly understand that, speaking generally, whatever is borne by the stem and its branches is a leaf of some kind , whether it be green,. as are foliage-leaves, or coloured, as are flower-leaves.

We have already remarked that the lowest leaves often seem to spring from the root. When this is the case these leaves may be called radical leaves. They really spring from a portion of the stem, which is more or less buried underground, giving off root-fibres below and radical-leaves from above. This portion of the stem in herbaceous plants which last more than a season or two is called the stock. The upper leaves, obviously springing from the stem, may be described as cauline.

The point on the stem from which any leaf is given off is called a node ; the space between two nodes is called an internode. It is owing to the non-development of the internodes of the lower part of the stem or of the stock that the leaves which it bears appear to be given off in a tuft.

Each leaf consists of stalk and blade, or of blade only ; the stalk supporting the blade is called a petiole. Leaves which consist of blade without any stalk are termed sessile. The same word is used of any part of a plant to denote the

I.] FLOWER-LEAVES. 5

absence of a stalk, whether that stalk be a petiole (which is the stalk of a foliage-leaf only) or not.

The blade may be entire, or more or less divided into segmcjits, or into separate pieces called leaflets. All the foliage-leaves have the blade spread out more or less horizontally, and they are all coloured green. They may be hairy , ox glabrous, that is, destitute of hairs.

We find, then, the foliage-leaves to be borne by, and around, the stem ; they are thin, coloured green, and consist of petiole and blade, or of blade only : the blade being spread out horizontally. We now come to the examination of the —

4. Flower; and as the structure of the flower varies very much in different kinds of Indian annual weeds, it will be

Fig. 2. Orange [Citrus Aurantium).

FLOWER-LEAVES.

[chap.

needful for us to select some well-known plant which we can speak of by name, so that we may avoid misunderstanding.

Perhaps we cannot do better than take, first, the Orange-flower, or the flower of one of its near allies, the Citron, Shaddock, or Lemon. The structure of the flowers of the latter is so similar to that of the flowers of the Orange, that any of them will do. As the leaves of which the flower consists are smaller than foliage-leaves, and very different from them in form, colour, and arrangement, it will be necessary that you be very careful in your observations, making sure that you thoroughly understand every stage of your progress.

The flower, observe, is borne upon a very short branch, which serves as a flower-stalk, and which is distinguished as the peduncle of the flower. Before proceeding to dissect (to separate carefully into its pieces) a flower, select one that has just opened, and which has lost none of the parts which it possessed while still a bud ; that is, before it expanded,

Observe, first, that all the coloured leaves which form the flower are apparently arranged upon the very extremity of

the little branch which serves as a flower-stalk. The internodes which separate the upper foliage-leaves of the stem cease, or are suppressed, in the flower, so that of flowers. The top of the flower-bearing branch, from which the flower-leaves collectively spring, is called the receptacle, or floral receptacle.

Fig. 3. Vertical section of the Flower of the Orange.

FLOWER-LEA VES.

5. Proceed next to note that the lowest and outermost part of the flower consists of a little cup with about five minute teeth upon its margin. These minute teeth indicate — as we shall become well assured as our experience widens — the number of leaves which are united to form the cup, each tooth answering to the tip of one of the little cohering leaves. These leaves are singly termed the Calyx-leaves, or Sepals , and together they form the Calyx of the flower, whether united, as in the Orange, or wholly separate, as in many common plants at hand in every garden. In the Orange the calyx remains after flowering, and may still be found even when the fruit is ripe. Such a calyx is said to be persistent.

We shall find it convenient to distinguish between a calyx which consists of separate calyx-leaves or sepals, and a calyx in which they are united more or less, terming the former polysepalous,1 the latter gamosepalous. • The calyx of the Orange is gamosepalous.

6. Immediately inside the calyx are normally five erect or slightly curved-back, separate, white, and wax-like leaves. These also are arranged in a whorl, and they are singly placed opposite to the intervals between the teeth of the calyx, not opposite to the teeth (sepals) themselves. Singly, they are the Corolla-leaves or Petals ; together they form the Corolla of the flower. The petals being free, the corolla is polypetalous ; being equal in size and form, it is also regular.

Unlike the calyx, the corolla falls away early, and hence may be described as deciduous.

1 This prefix (no\C, many) is used when applied to sepals and petals , to denote that the sepals or petals are free rather than that they are actually many in number. Usually there are not more than three, four, or five sepals or petals in a flower.

FLOWER-LEA VES.

[chap.

7. In the examination of the rest of the- flower much nicety is required. Having stripped off the calyx and petals singly, and laid them aside, proceed to the third series of flower-leaves. These are very different in form and structure from both sepals and petals. They consist each of a lower stalk-like portion, bearing an upper, somewhat thickened, oblong, and grooved head. This stalk is termed

Fig. 5. Three Pollen-grains of the same.

Nq

the fila7nent , the oblong head which it supports, the anther; and the filament and anther together constitute a Staminal leaf or Sta?ne?i. The stamens of the Orange are a little shorter than the petals. As they are united to each other by their filaments into sets of variable numbers, they are said to be polyadelphous.

The anther we must examine more closely. We have already observed that there is a groove up the back (outer side), and another, less distinct, along the face (inner side). These grooves divide the anther into two lobes, right and left. If the anther be ripe, each of these lobes will split open near the edge, allowing certain fine powdery granules which it contains to be easily removed by insects or otherwise. These granules are essential to the flower as well as

FL 0 WE R- LEA VES.

to the stamen, so we must carefully examine them under a microscope. Fig. 5 shows them highly magnified. We find that they are distinct globular cells, with minutely granular contents. The fine powder is the pollen , and each of its globular cells is a pollen-grain.

Remove all the stamens, noting that they are, like the leaves of the corolla and calyx, inserted directly upon the floral receptacle, and immediately underneath the central organ of the flower. Such being the case, they are technically described as hypogynous.

8. You have now left in the centre of the flower, slightly raised upon a thickened cushion or ring, called the disk, the germ of the future fruit. If the lower part be cut across, you find it to be divided into a number of small cavities, radiating from the centre, each cavity containing the minute rudiments of future seeds. If you take the pains to count the number of cavities (you will probably find them about ten ; they vary from seven to fifteen), you will ascertain the number of leaves which are united to form this central organ of the flower, which we shall speak of as the pistil. But how am I to convince you that the pistil is really composed of united leaves ? It would not be easy to make this clear without reference to some other flower in which the pistil is of much simpler structure than in the orange-flower, so that I must ask you to lay it aside for a short interval while we examine the pistil of some peaflower. Take the flower of the common Field or Garden-pea itself, or of a Scarlet-runner or Haricot, of Lablab, Chick-pea, Sunn-hemp, or Indigo. Any of them will serve, and one or another

Fig. 6. A longitudinal section of the Pistil of Orange, showing the interior of the ovary, with ovules, and style thickened upwards into the stigma.

FL 0 WER-LEA VES.

[chap.

cannot fail to be at hand. Let us suppose that you have gatheied a flower of the Common Pea. The other plants with pea-flowers differ from it but slightly so far as the pistil is concerped.

The calyx, you observe, is deeply five-toothed, indicating that it is composed of five sepals, as in the orange. As the sepals are united below, the calyx is gamosepalous. The corolla consists of five petals, the uppermost of which is much larger than the rest ; so that the corolla is said to be irregular. The same term is applied to any corolla or calyx the parts of which are unequal in size or form.

Remove the petals carefully, especially the two lower ones, which are united below by their edges into a boatshaped sheath called the keel. The keel encloses the stamens, which in the Pea are, excepting one, united by their filaments into a sheath, which is split open along the upper side. The single separate stamen is on the upper side of

Fig. 7. Section of Flower of Garden Pea.

Fig. 8. Diadelphous Stamens of same.

FLO WER-LEA VES.

IX the sheath next to the large petal. Stamens united thus by their filaments into two sets are said to be diadelphous.

Carefully cut away the stamens, and the central organ of the flower, the pistil, remains, corresponding to the pistil of the Orange. Cut across with a sharp knife in its thickest part, you find that it contains but a single cavity, and that the minute rudiments of the future seeds are arranged in a line upon the inner angle of the cavity. These minute rudiments of the seeds are called, in their present stage, the ovules , and the hollow leaf which contains and protects them is called a carpellary leaf, or carpel; the lower, hollow part, containing the ovules, being distinguished as the ovary.

Fig. q. Pistil of Common Pea, enlarged. The minute stigma occupies the outer notch immediately within the apex of the bearded style.

The carpel is prolonged beyond the ovary into a long, slightly flattened, up-curved tip, bearded with a row of short hairs along its inner face. At the oblique apex immediately beyond the hairs is a minute naked projection, not discernible without care, with a soft and cellular surface upon one side.

This cellular surface is termed the stigma. It is invariably present, and usually much more conspicuous than it is in the Pea. The stigma does not rest immediately

FLOWER-LEA VES.

[ciiap.

upon the top of the ovary in the pistil of the' Pea, but it is separated from it by a distinct stalk, abruptly narrowed where it joins the ovary. This stalk supporting the stigma is called the style. In many plants the stigma is without a stalk, and rests upon the top of the ovary. When this is the case, it is described as being sessile. In the Pea, then, we have a pistil consisting of a single carpellary-leaf answering to a foliage-leaf, a calyx-leaf, a corolla-leaf or a staminal-leaf, but differing from each of these in having the margins curled in and united about half of its length, so that it becomes hollow, and suited to protect the delicate seed-buds (ovules) which are borne inside upon its united margins.

Suppose, now, that instead of a single carpellary-leaf in the flower, there were ten or fifteen of them arranged in a close ring around the centre. The inner angle (that is, the angle turned towards the centre of the flower) of each carpel would correspond to the line of union of the edges of the same carpel, and upon this inner angle the ovules would be attached. If we suppose, further, all of these carpels to cohere together into a single organ, we should have a pistil similar to that of the orange-flower. The main difference between the pistil of the Pea and that of the Orange is simply this : that in the former tire pistil consists of a single carpel, in the latter of a number of cohering carpels. A pistil consisting of a single carpel, or of two or more carpels which do not cohere, is said to be apocarpous. A pistil consisting of two or more carpels cohering, though the extent of their union be ever so slight, is said to be syncarpous. The pistil of the Pea is apocarpous ; that of the Orange is syncarpous. In each of them we have an ovary — in the former one-celled, in the latter many-celled — style, and stigma.

FRUIT.

As the pistil in the Orange is wholly free from the calyx, it (or rather the ovary) is said to be superior.

9. Gather now another orange-flower; one in a more advanced state, with the petals and stamens all fallen away, and only the pistil remaining. The pistil here is passing into Fruit. The style and stigma have withered up more or less, and probably fallen away altogether, leaving a scar on the top of the enlarged ovary, which has now become an “ orange.” In the ripe orange, as in the pistil at the time of flowering, the carpels continue to cohere, and their thin membranous sides divide the fruit into many cells. The principal change is due to the great increase in size of the ovary, to the formation of a quantity of juicy acid pulp in its cells, and to the development of the ovules into perfect seeds, one or more of which you may usually find in each cell of the fruit.

If we cut a ripe, plump seed right through lengthwise, we shall find that it consists of a tough, horny coat, the testa , enclosing one, or often two or more crumpled embryos , the germ of future orange-trees. It is so difficult to understand the structure of the embryo in the seed of the Orange, owing to the exceptional circumstance (which, however, is the rule in the Orange) of its containing more than one embryo, that we shall be obliged to go back to the Pea, or some other pea-flower, the seeds of which contain but a single embryo. Take a Pea, and, if hard, soften it by soaking it overnight, or by boiling it for a few seconds, so that you may strip off the testa enclosing the embryo. But before doing so, observe, first, the black spot on the side of the seed. This indicates the part by which the seed was attached to the fruit-carpel ( pericarp ) in which it was enclosed ; it is the scar left on its separation from it. It is called the hilum. On careful examination you may

SEED.

[chap.

observe at one end of the hilum a very minute aperture through the skin of the seed. You may find it by squeezing the soaked seed, when moisture issues from it. This is the micropyle ; it answers to the micropyle of the ovule (see page 26). Generally, in ripe seeds, it is obliterated, or too minute to be observed.

As soon as the testa is removed, you find that its entire contents easily separate into halves, each half being plane on the inner face, and rounded on the outer. Observe, also, that these halves or lobes are hinged together at one side. Separate the lobes carefully, and you may observe upon the margin of the inner face of one of the lobes, close by the hinge, a rudimentary bud and root. You find, then, enclosed by the testa, (1) one pair of large seed-leaves;

Fig. 10. Embryo of Pea with the Fig. ii. Seed of same before removal of

(2) a bud with minute, rudimentary foliage-leaves ; and

(3) the rudiment of a root. Nothing more. These parts are indicated in the cut, which shows the seed-leaves with their inner faces exposed. The seed-leaves are called cotyledons. To the right is the bud of the stem, slightly curved inwards, called the plumule; and, pointing downwards, the rudiment of the root, called the radicle: the extremity of the cotyledons laid open, showing the curved plumule and radicle.

the testa, showing the hilum and ridge above indicating the position of the radicle inside.

SUMMARY.

radicle invariably nestles immediately within the micropyle. The seed-leaves, or cotyledons, of the Pea are opposite ; so we have an embryo with a pair of cotyledons, or a Dicotyledonous embryo.

Sow, if you please, a few peas, or a few orange-pips. Under favourable circumstances they will germinate, and grow up into plants similar to their parents.

10. Before we proceed to future chapters, in which we shall inquire into the relation of the various parts of the plant to each other, into the office or function which each is intended to perform, and the relation which the organs of other plants bear to the organs of the common species just examined, let us recapitulate the different parts which we have observed thus far. If there be any part which has not been clearly made out, make a point of understanding it before proceeding further.

We have, first, a Root, which descends into the soil, gives off fibrils irregularly, and is pale-coloured ; the fibres have their extremities sheathed, and, as they do not give off the rudiments of leaves, the root is leafless. It is at first directly continuous with, and appears to pass into, the stem ; but in plants which are fully grown, the original root is usually supplemented by other root-fibres which are given off from the bottom of the stem.

The Stem ascends, bears foliage-leaves, from the axils of some of which branches usually spring ; it is coloured green more or less, and either itself terminates, or certain of its branches, in a tuft of coloured leaves forming the flower.

Root and stem, therefore, we find opposed to each other in the directions which they respectively take, as well as in several important points of structure. Together they may be regarded as constituting the axis of the plant ; the root being the descending , the stem the ascending portion of the i6

SUMMARY.

[CHAP. 1.

axis. Upon the ascending axis all the leaves, both foliage and flower-leaves, are arranged. The plant thus consists of axis and appendages.

Leaves. — These, we have found, are of five different kinds. First are the radical and cauline

(1) Foliage-leaves , called simply leaves.1

Then come the Flowers, terminating the stem or its branches, consisting of —

(2) Calyx-leaves , called sepals.

(3) Corolla-leaves , called petals.

(4) Staminal leaves , called stamens.

(5) Carpellary leaves , called carpels.

1 In many plants we may distinguish two modifications of the leaf below the flower-leaves, besides the green foliage-leaves, but it is not important to distinguish these at present.

Chapter II. What The Root, Stem, And Leaves Have To Do

1. The plant fades. Why? Experiment shows that it is because

water is withheld.

2. The root an absorbing organ.

3. Water is exhaled from the leaves. Transpiration. Absorption.

4. Other substances, besides water, are absorbed. The ash, and inor-

ganic constituents of plants.

5. The organic compounds of carbon, oxygen, hydrogen, and nitrogen. *6. Ternary and quaternary compounds of these elements are in

contrast.

7. Source of carbon in carbonic acid.

8. Liberation of oxygen by plants under the influence of sunlight.