BOTANY.

BOTANY is the science of plants. It teaches their natural history and intrinsic qualities; and, to facilitate an acquaintance with these particulars, arranges all vegetables in classes, orders, and other subdivisions. This arrangement is called a system. Various systems, or plans of arrangement, have been from time to time proposed; but the sexual system of Linnæus is at present generally received. This naturalist has drawn a continued analogy between the vegetable economy and that of the animal; and has derived all his classes, orders, and genera, from the number, situation, and proportion of the parts of fructification. In twenty-four classes, he has comprehended every known genus and species. In considering a plant with a view to its characteristics or distinguishing features, it is divided by Linnæus into the following parts, making so many outlines, to which the attention of the botanical observer must be directed: 1. Root; 2. Trunk; 3. Leaves; 4. Props; 5. Fructification; 6. Inflorescence. 1. The root consists of two parts, the caudex and the radicula. The caudex, or stump, is the body or knob of the root from which the trunk and branches ascend, and the fibrous roots descend, and is either solid, bulbous, or tuberous: solid, as in trees and other examples; bulbous, as in tulips, &c.; tuberous, as in potatoes, &c. The radicula is the fibrous part of the root, branching from the caudex. 2. The trunk, which includes the branches, is that part which rises immediately from the caudex, is either herbaceous, shrubby, or arborescent, and admits of several other distinctions, according to its shape, substance, surface, &c. 3. The leaves are either simple, as those that adhere to the branch singly, or compound, as when several expand from one footstalk. Leaves are farther described by various terms indicative of their form and outline. 4. The props, those external parts which strengthen, support, or defend the plants on which they are found, or serve to

facilitate some necessary secretion: as, the petiolus, or footstalk of the leaf; the pedunculus, or footstalk of the flower; the stipula, or husk, that is, the small leaves that generally surround the stalk at its divisions; the cirrhus, or tendril; the pubes, or down; the arma, or defensive weapon, as thorns. 5. The fructification, or mode of fruit-bearing. 6. The inflorescence, or mode by which the flowers are joined to the several peduncles.

The various parts of a flower are arranged under distinct heads, consisting of the "Calyx" or Empalement: the "Blossom" or Corolla: "Stamens" or Chives: "Pistils" or Pointals: "Seed Vessels" or Pericarpium, and "Seeds" or Semina. To these are to be added the "Nectary" and "Receptacle." The calyx is formed of one or more green or yellowish-green leaves placed at a small distance from, or close to the blossom. There are different kinds of calyxes, as the perianthium or cup near the flower, in the rose-the involucrum, remote from the flower, in umbelliferous plants, as is seen in the hemlock and carrot:-the catkin, or amentum, as in the willow or hazel:-the sheath, or spatha, in the snow-drop:—the husk, or gluma, in wheat, oats, and different kinds of grasses:-the veil, or calyptra, covering the fructification of some of the mosses, and resembling an extinguisher: -the curtain, or volva, surrounding the stems, and attached to the pileus, or cap, that spreading part which forms the top of several fungi, and covers the fructification, and which in the common mushroom covers the gills.

The Blossom is that beautifully coloured part of a flower, which principally attracts the attention. It is composed of one or more petals, or blossom-leaves. When it is united in one, as in the Polyanthus or Auricula, it is termed a blossom of one petal, but if it be composed of many parts, it is then said to be a blossom of two, three, or many petals.

The Stamens are slender thread-like substances, generally placed within the blossom, and surrounding the Pistils. It is composed of two parts, the Filament or Thread, and the Anther or Tip, but the latter is the essential.

A Pistil consists of three divisions, the Germen or Seed-bud, the Style or Shaft, and the Summit or Stigma; but the second

is often wanting. Some flowers have only one Pistil: others have two, three, four, &c., or more than can easily be counted. The Seed-Vessel, in the newly-opening flower, is called the Germen; but when it enlarges it is termed the Seed-Vessel. Soine plants have no appendage of the kind, and then the seeds are uncovered, as in the dead nettle; the cup, however, generally incloses and retains the seeds till they ripen: and in the tribe of grasses, this friendly office is generally performed by what was previously called the blossom. Seeds are sufficiently well known to render a description unnecessary: the part to which they are affixed within the Seed-Vessel, is termed the Receptacle of the seeds.

Nectaries are those parts in a flower which are designed to prepare a sweet nectareous liquor. The tube of the blossom, as in the honey-suckle, frequently answers the purpose; but in many other flowers, there is a peculiar organization for the purpose. At the base of the petal, in the crown imperial, the Nectary is a very peculiar one, containing the liquor, from which, as there are few flowers in a greater or less degree unprovided with it, the little industrious bee derives its honey.

The Receptacle is the seat or base to which the various divisions of a flower are affixed, Thus, if you pull off the Calyx, the Blossoms, the Stamens, the Pistils, and the Seeds or SeedVessel, the substance remaining on the top of the stalk is the Receptacle. In many plants it is not particularly striking, but in others it is remarkably so; thus, in the artichoke, after removing the Calyx, the Blossoms, and the bristly substances, the remaining part, so highly esteemed for the table, is the Receptacle.

The Classes are next to be considered, which were, according to the system of Linnæus, divided into twenty-four.

The characters are taken either from the number, length, connexion, or situation of the Stamens.

The first class comprehends all that have a single stamen in each blossom, and this he calls monandria (one male); the second class such as have two stamina, called diandria (two males);

the third, fourth, and so on, up to the tenth, are named in the same way, triandria (three males), tetrandria (four males), &c. &c. There being no plants with eleven stamina, and the number not being uniformly twelve in many plants, though there or thereabouts, the eleventh class, called dodecandria (twelve males), includes all plants that have from eleven to nineteen inclusive. If the stamina are twenty or more, and are attached to the calyx or corolla, the plants belong to the twelfth class. icosandria (twenty males). If above nineteen, and attached to the base of the flower, and not to the calyx or corolla, they are of the class polyandria (many males), which is the thirteenth class. Plants with four stamina, two of which are shorter than the other two, are in the fourteenth class, didynamia (two powers). Plants with four long and two short stamina constitute the fifteenth class, the tetradynamia (four powers). In monadelphia, which is the name of the sixteenth class, the threads of the stamina are all united at bottom, but the antheræ are separate. In diadelphia the threads are united, not altogether, but in two bodies. In polyadelphia they are connected in three or more bodies. If the threads are separate, but the antheræ united, the plant is in the nineteenth class, syngenesia. In all the above classes the stamina are distinct, and separate from the pistillum; but where the former grow upon the latter, the plant is of the class gynandria, which is the twentieth. Sometimes the stamina are in one blossom, and the pistillum or pistilla in another but on the same plant: in this case they form the class monacia (one house). But if the staminiferous blossom is on one plant, and the pistilliferous on another, it is of the twenty-second class, diæcia (two houses). And lastly, if some blossoms have both stamina and pistilla, and others only one or the other, whether on the same plant, or on different plants, they come under the twenty-third class, polygamia. These include all vegetables whose flowers are conspicuous. But there are some, as mosses, sea-weeds, mushrooms, &c., whose flowers are inconspicuous, or whose parts of fructification are not stamina and pistilla. These are all arranged together in the twenty-fourth class, called cryptogamia.

These 24 classes have been recently reduced to 20, which may be thus arranged with examples under each.

A knowledge of the Orders may be very easily attained, by observing that,

In the class Didynamia, they depend upon the seeas having a

seed-vessel, or not.

Tetradynamia, upon the shape of the seed-vessel.
Syngenesia, upon the structure of the florets.

Cryptogamia, upon the natural assemblages of plants resembling each other.

And that in all the other classes, excepting Monadelphia, Dia|delphia, and Polvadelphia, they depend upon the number of pistils only. In determining the number of pistils, count the styles, as they appear at their bottom part, or base; but if the summits are not supported upon styles, then count the summits. Recapitulation of the Classes, with their attendant Orders and familiar examples.

Monandria.

Order Monogynia (1 pistil) Common Stonewort.

Digynia.. (2 pistils) Water Fennel.

Tetragynia (4 pistils) Pondweed.