The limits between a bulbous and tuberous root are not easily defined; the solid bulb seems to partake of the nature of both. Bulbs usually die after the blossoming of the plant; 'but new bulbs are often formed from the base or sides of the original bulb, which in their turn produce plants. This is the fact with

respect to the orchis tribe; in which every year one bulb or tuber dies, and the other throws out a new stem; by this means it changes its position, though very slowly, since it takes but one very short step each year. The production by means of bulbs, is only a continuation of the old plant, while by means of the seed a new plant is brought forth.

This is an important distinction; and it is observed that in process of time, a plant continued by means of reproduction, whether by bulbs, grafting, or any other manner, ultimately dwindles and degenerates as if worn out with old age, and it becomes necessary to renew its vigour by producing a young plant from the seed. This is the case with the potatoe, which is ordinarily produced from the root; but the farmer often finds his stock dégenerated, and is obliged to provide himself with new roots produced from the seed.

The specific character of plants is sometimes taken from the root, and in some cases the specific name; as SOLANUM tuberosum, the potatoe, and RANUNCULUS bulbosus, the bulbous ranunculus. The tuberous and bulbous roots distinguish those species from all others of the families Solanum, and Ranunculus.

The forms of roots are so various, that it is impossible to give names to all; even in the same species of plants, the root presents many varieties of form. In the potatoe, for example, we see some roots round, and of an even surface, others, long or oval, and some very knobbed and irregular; but yet amidst all this variety there is a prevailing uniformity, and we can usually at one glance distinguish a potatoe, by its form, from all other vegetables. It might, at first, have appeared as if there could be little interesting in the consideration of roots, which are destitute of that symmetry of parts and liveliness of colouring, which is exhibited in other organs of the plant. We find, on casting a rapid glance over the face of the earth, that all this variety in the form of roots is not without its peculiar use. Mountains being exposed to winds, we find them covered with plants which have branching roots with strong and woody fibres. These, fastening themselves into the clefts of rocks,

Difference between the continuation of plants by bulbs, &c. and by raising from the seed-Specific character and name taken from the roots-Roots of the same species sometimes vary in form-Utility in the variety of form in roots.

take firm hold, and the trees they support seem, undauntedly, to brave the violence of storms and tempests. Spindle roots abound in rich, soft grounds, which they can easily penetrate. Damp and loose soils are rendered fit for the use of man, by being bound together by creeping and fibrous roots. We find here, as in every part of nature, proofs of a wise Creator, who makes nought,

"In vain, or not for admirable ends." We have now described those roots which grow by being fixed in the earth. But besides these, there are plants which are not fixed, but float about in the water; some grow upon other plants, and some seem to derive sustenance from air alone.

Of the first kind, or aquatic roots, is the Lemna or duckmeat, which grows in stagnant water, having thread-like roots, not confined to any fixed place. The water-star grass,* previous to its blossoming, floats about, and is nourished by its suspended fibres; after flowering, it sinks to the bottom, its roots become fixed and its seeds ripen. These seeds germinating, a new race of plants appear, which rise to the surface of the water, blossom and sink to the earth, producing in turn their successors. Some of the Cryptogamous plants, particularly of the genus Fucus, exist in a wandering manner, often forming islands of considerable size. In the Gulf of Florida, the Fucus natans is very abundant; this, by voyagers, is often called gulf-weed, and is sometimes found in masses extending many miles, and,

Wher'er the surge may sweep, the tempest's breath prevail."

How strikingly analagous this poor weed to many a human being, blown about on the ocean of life, by every breath of passion or caprice! Who would not rather, like the mountain oak, meet the storms of life firmly rooted in virtuous principles, than to be floated along even by the breath of pleasure, without end or aim, forgetful of the past and careless of the future? To the virtuous, afflictions serve but to strengthen them in goodness; so,

"Yonder oaks! superior to the power

Of all the warring winds of heaven do rise,
And from the stormy promontory tower;

While each assailing blast increase of strength supplies."

We find roots which grow on other plants, appearing to derive sustenance from their juices. These are called parasites; this term is often applied to persons who are willing to live in dependence upon others; and so despicable does this trait of character appear, that we almost conceive it a kind of mean* Callitriche aquatica.

Aquatic roots-Parasitic plants.

ness, even for a plant to live without elaborating its own food. Parasitic plants are common in tropical regions; sometimes many kinds are found upon the same tree, presenting a curious variety of foliage. In our climate, except in the Cryptogamous family, as lichens, mosses, &c. we have but few genera of these plants.* The Dodder and Misletoe are celebrated parasitic plants.

Some plants grow without roots; these are called air plants : they are furnished with leaves or stems which seem to inhale, but not to exhale fluids; their substance is usually fleshy and juicy; some of them flourish in the most dry and sandy places, exposed to a burning sun; as the Stapelia, sometimes called the vegetable camel. The Epedendrum grows and blossoms for years, suspended from the ceiling of a room and nourished only by air.

Many roots, as the rhubarb, wild-turnip, blood-root, &c. possess important medicinal properties. The growth of the root is most rapid in autumn; at this season, the sun being less powerful and the air more charged with moisture, the juices condense in the lower part of the plant, and nourish it, but as the season becomes cold, vegetation is checked; the winter is, therefore, the time to collect roots for medicinal purposes.

Stems and stalks.

The trunk or stem is the body of a plant, whether it be a tree like the oak, a shrub like the lilac, or an herb like the peppermint or sage; its use is to sustain the branches, leaves, and flowers; and it serves as an organ of communication between them and the root, conducting from the latter to the former, animal and vegetable substances, the salts and earthy matter which the radicles by their mouths, suck up for the nourishment of the plant.

If a plant be watered by any coloured liquid, the stem will in time, shew that this fluid has ascended into it. This organ also contains a set of vessels which carry downwards certain juices, which have passed through peculiar processes in the leaves of the plant.

But of the circulation of fluids in the vegetable substance we shall speak more particularly hereafter. Our present object is, to describe the external appearance of the vegetable

* In the vicinity of Troy I have seen a very beautiful species of the Pterospora, growing upon a branch of the whortle berry. Its colour was a bright crimson, which contrasted finely with the white flowers, and green leaves of the plant on which it grew.

Air plants--Proper time to collect roots for medicinal purposes--Trunk-Its use.

organs and not their internal structure; or, in other words, it is the anatomy and not the physiology of plants, which we are now attempting to explain.

The different kinds of stems, or stalks, have been divided into seven classes, as follows—

Caulis, or proper stem, Culm, Scape, Peduncle, Petiole, Frond and Stipe. Fig. 20.

1st. Caulis or proper stem, is such as is seen in forest trees, in shrubs, and in most annual plants. The caulis is either simple, as in the white lily; or branching as in the geranium; the branching is the more common form. You have here Fig. 20, the representation of a caulis, or proper stem, (a); a peduncle, or flower stalk, (b); and the petiole, or leaf stalk, (c).

a

Fig. 21.

2d. Culm, or straw, (Fig. 21) is the kind of stem which you see in grasses and rushes. The culm is either without knots, as in the bulrush, jointed or knotted, as in wheat and indian corn, geniculated or bent like an elbow, as in some of the grasses; those culms which are bent, are also knotted, though they may be knotted without being bent. The Bamboo, Sugar Cane, and various species of Reeds have stems of the culm kind'; some of them, particularly the Bamboo, are known to attain the height of forty feet.

*This kind of stem is by the French called tige; the i should be sounded g soft like j, as teje. The word Caulis is from the Greek Kaulos, a

like e, the

stem.

Division of stems--Caulis--Culm.

Fig, 22.

3d. Scape, (Fig. 22, a, a,) a stalk springing from the root, which bears the flower and fruit, but not the leaves; as the Dandelion, the Cowslip, and the Lily of the Valley. Plants with scapes are sometimes called stemless plants; in this case, the scape would be considered as a peduncle proceeding from the root.

4th. Peduncle, or flower stalk, is but a subdivision of the caulis or stem, (See Fig. 20, b,); it bears the flower and fruit, but not the leaves; when the peduncle is divided, each subdivision is called a pedicel.*

The peduncle, or flower stalk, is,

Cauline, when it grows immediately out of the main stem;
Rameous, or branching, when it grows out of a main branch;

Axillary, growing between a leaf and stem, or between a branch and stem;
Terminal, when it terminates a stem or branch;

Lateral, when situated on the side of a stem or branch;

Uni-flora, bearing one flower; bi-flora, two flowers; tri-flora, three flowers; Multi-flora, bearing many flowers.

When there is no peduncle or flower stalk, the flowers are said to be sessile.

5th. Petiole, or leaf stalk, is a kind of stem, like a fulcrum, supporting the leaf (See Fig. 20, a,); it is usually green, and appears to be a part of the leaf itself. The petiole of many plants is somewhat in the form of a cylinder; but the upper surface is rather flattened, the under surface convex. You will find this remark useful, in distinguishing the foot-stalks of compound leaves, from young branches, with which they are sometimes confounded. In most cases, the leaves and flowers are supported by distinct foot-stalks, but sometimes the foot-stalk supports both the leaf and flower.

The petiole may be,

Terete, round, as in the Holly-hock;

Semi-Terete, half round, as in the Yellow water-lily;

Compressed, flattened, as the Poplar;

Alated, winged, or furnished on each side with a leafy appendage;
Cirriferus, having tendrils, as the Pea;

Climbing, performing the office of a tendril, as the CLEMATIS virginica.
The Petiole is often compared with the leaf, as the peduncle

is with the flower, with regard to their relative length.

In determining the species of plants, we often consider the length of the peduncle, compared with the flower: as whether the peduncles are longer or shorter than the flower.

Scape-Peduncle-Petiole.