Wild Flowers.

PART I.

ORGANS OF PLANTS.

THE COVERING, SKIN, OR EPIDERMIS OF PLANTS.

PLANTS, like animals, have a skin, that is, have an outward covering, which protects and assists to bind together the internal structures. Generally, this skin, which is composed of two layers, is extremely thin, as we find it on most leaves, and is usually colourless, allowing the varied tints of the parts beneath to shine through it. In most plants the skin or epidermis is simple; but in some, such as the grasses, horsetails, &c., it contains silica or sand substance, and from this derives peculiar hardness.* The hard, shining surface of straw owes its character mainly to the presence of this silica. In the bamboos it occurs in masses called tabasheer. Moreover the plant covering is not impervious, but is pierced with numberless minute openings called stomates.-Fig. 1. These openings communicate

* The use of what are called Dutch rushes in polishing brass, &c., depends upon their containing a large amount of this silica, or sand substance, in their epidermis.

with the interior parts of the plant, and permit the interchange of gases and vapours with the surrounding atmosphere: they are, in fact, the breathing mouths of plants. Capable, too, are they

flattened cells of which it is

or breathing pores-a, a.

of shutting up in dry weather,

and so checking the escape of the vegetable juices, and of opening to receive grateful refreshment in a moist atmosphere. As we might expect, 1. Portion of the epidermis or these stomates would be of but skin of a plant, highly magnified, showing the irregular-shaped little use on roots, or on plants composed, and the stomata, immersed in water, and there we scarcely find them; they are most numerous on the under sides of leaves; a tolerably good microscope, however, is required to see them. Plants, moreover, which are natives of very dry and parching climates have but few stomates; so that they do not readily part with their moisture of this the succulent cactus tribe is a well-marked example. But the plant covering has appendages much less microscopic than these curious little stomates; occasionally it is smooth, but very often it has a clothing of hairs of all kinds, from the softest down to the stiffest bristles, merging into the spines and prickles which arm our roses and brambles, or into the stings of the nettle. The disposition and form of the hair coverings of plants often afford us valuable distinctions. Pluck a piece of chickweed, or of the germander speedwell, Veronica chamædrys. On the stem of the first you will perceive alternate lines of hairs, on that of the second opposite lines of hairs, both well marked characters.

Most

hairs perhaps are simple, but many are varied; some are star-shaped-Fig. 2 b-others forked-Fig. 2 aothers glandular-Fig. 2 c.

The stains and markings of the epidermis cannot be called appendages,

but they are characters, often of much value in determining plant distinctions. For instance, the true hemlock has a stem perfectly destitute of hair appendages, but strongly marked with

と

2. Varieties of plant hairs-a, forked hair-b, star-shaped hair-c, branched

dark stains; this character alone distinguishes it from every other British and glandular hair of Gooseberry. species of the extensive family—the Umbelliferæ-to which it belongs.

Having looked well to our plant covering, we must go to what very few incipient botanists trouble themselves about

THE ROOT.

And yet roots are often beautiful-yes, beautiful; oftener still, remarkably characteristic-very varied in form. Although the root is usually the part of the plant by which it is fixed in the ground, and by means of which it draws up nourishment, the arrangement is by no means constant; some of the orchis family, and others, do not have their roots in the ground at all, but possess what are called aërial roots, which draw nourishment from the atmosphere; others develop their roots in the air in the first

place, although they subsequently become fixed in the earth. Water-plants shoot out their roots in the midst of the element in which they grow.

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Roots are classed as annual, biennial, and peren- ! nial, according as they last, for one, two, or more years. A root may be said to consist of two parts, the body, or, as it is often called, the caudex, and the radicles or fibres. Some roots, like the carrot, dandelion, &c., are simple, and terminate in a point; others terminate abruptly, as in the devil's-bit scabious, mentioned among our September wild flowers; whilst some are globular, like the turnip. Many roots, like those of the majority of the grasses, and the sedges, are composed solely of fibres. Perhaps, however, the commonest form of root is the branched, such as we find possessed by trees and shrubs generally. Of the curious roots, that of

3. Root of the Ipecacuanha-annulated or ringed.

4. Root of Bird's-nest Orchis, composed of many fleshy fibres-a fasciculated or bundled root.

It

the ipecacuanha-Fig. 3-is not the least so. is annulated or ringed. Another form of root, the fasciculated or bundled-Fig. 4-we see in the bird's-nest orchis, approaching the tuberous roots of others of the orchis species. Here is one-Fig. 5— the palmated root of the common Orchis maculata, or spotted-leaved orchis.

Properly, however, we ought to speak of these tubers, and of others like them, such as those of the potato, rather as appendages to the root than the root itself. Some of our readers, perhaps, are ready to

5. Root of the Spotted Orchis, with palmated (hand-shaped) tubers.

remind us that we have forgotten to speak of bulbs; but for these we must refer them to our next section, the stem, to which, perhaps to their surprise, they will find these apparent roots truly belong; for as there are aërial roots, so are there underground stems.

THE STEM.

The stem is that portion of the plant which, as a general rule, rises from the root at the surface of the ground, and supports the leaves, flowers, &c. It is not, however, an essential part of plant existence, many species, such as the primrose, plantain, &c., having no apparent stem whatever, whilst others possessing bulbs, like the onion or lily, or solid corms, like the crocus, are said to have their stems under ground. Fig. 6 is a section of