PART I.

METHOD OF CLASSIFYING PLANTS INTO FAMILIES, AND

UNDER GENERAL DIVISIONS.

CHAPTER I.

CLASSIFICATION FOUNDED UPON ESSENTIAL ORGANS.

"Now spring the living herbs, profusely wild,
O'er all the deep-green earth, beyond the power
Of botanist to number up their tribes:
Whether he steal along the lonely dale

In silent search; or through the forest, rank
With what the dull incurious weeds account,
Burst his blind way; or climb the mountain rock,
Fired by the nodding verdure of its brow.

With such a liberal hand has Nature flung

Their seeds abroad; blown them about in winds,

Innumerous mixed them with the nursing mould,
The moist'ning current, and prolific rain."

§ 1. Classification.-Plants are classified according to the structure of their essential organs.

The organs most essential are those that produce and contain the seed. Difference in the structure of these organs is

mostly accompanied by peculiarities in the other parts of the plant.

(a.) Species. Each particular kind of plant is called a species. The species is propagated by seed. It is wonderful how exactly the essential character of the species is perpetuated, even to fine hairs and markings. The violet we gather from the hedge-bank has the same form, minute arrangement of parts, colour, and fragrance, as that of a century ago, or of a hundred miles distant. There are often varieties, such as the white violet, double-flowered, &c. Such variations are the result principally of soil and culture, and can only be propagated by cuttings, or by parting the roots.

(b.) Genus.-Many species closely resemble each other. Such for instance as the sweet violet, the dog violet, the pansy, &c. As all these have the same general structure, they belong to one genus. Some genera include only a few species, others a considerable number. When the species so closely resemble as only to be distinguished with great difficulty, ordinary observers will be satisfied with knowing the genus only. This remark applies especially to the brambles, willows, sedges, &c.

N.B. In the scientific name of a plant, the first word indicates the genus, the second word the species. Thus, the fragrant violet is Viola odorata; the dog violet, Viola canina; the pansy, Viola tricolor. Other species of this genus are, V. palustris, V. lactea, &c. If there be a third name, this is usually indicative of a variety.

(c.) Family. The genera themselves often resemble each other in some important particulars, and are thus naturally allied. A group of similar genera is a natural order or family. Thus;

hemlock, carrot, parsley, celery, fennel, and chervil, though each belonging to a different genus, yet resemble in having flowers and fruit constructed upon a common principle, and arranged in a peculiar form of inflorescence called an umbel. (Plate III. Fig. 4.) These and all other genera resembling them, belong to the important and well-defined family called the umbelliferous. Again; daisy, dandelion, camomile, thistle, and blue-bottle, having composite or compound flowers, i.e., flowers consisting of many smaller flowers called florets, belong to the composite family. (Plate III. Fig. 5.) Some families being very extensive are subdivided into tribes, such as the rosaceous family into tribes of which the meadow-sweet, apple, plum, rose, cinquefoil, and burnet are representatives. Now as there are above a hundred families of British wild plants, besides many more that are peculiar to other parts of the world, it is necessary to arrange them under well-defined divisions. The principles of such an arrangement will be explained in the following sections.

§ 2. Phonogamous and Cryptogamous.—These are the two primary divisions of plants. The distinction is better known by the terms FLOWERING and FLOWERLESS. Phonogamous or flowering plants produce their seed by means of flowers containing stamens and pistils.

(a.) Pistil. (Plate II. Fig. 1, 2, 9.)—The central part of a flower is the most essential, and consists of one or more columns or variously shaped bodies, called the pistil or pistils. The pistil consists of two essential parts, and most frequently with an intermediate one also. The lowest part, attached to the receptacle or summit of the flower-stalk, contains the young seed or ovules, and is called the ovary. (Fig. 1 b. 2 b.)

The

summit of the pistil is called the stigma, and is often divided. If there be an intermediate part, generally

(Fig. 1 a. 2 a.)

a thread or column, it is called the style. (Fig. 1 c.)

(b.) Carpel. The structure of the ovary is very curious and beautiful. It may be explained by imagining it to be formed by one or more minute delicate leaves, folded by the edges and forming cells. Each of such supposed leaves is called a carpel, and bears one or more ovules within its cavity. (Fig. 2.) If there be several pistils, then each consists of one carpel containing one row of seeds. This is exemplified in the buttercup, monkshood, columbine, and larkspur, and may be seen more. distinctly when the seed is ripe, as the seed-vessels consist of the matured carpels.

Several carpels are often united into one pistil, and in this case their sides divide the ovary into several cells, each containing a row of seeds (Fig. 3); or else the divisions are obliterated, as in the seed-vessels of the poppy and violet, and then the ovary is one-celled, but contains several rows of seeds.

As the fruit consists of the ovary with some other portions of the flower attached, it not unfrequently exhibits the carpels very distinctly. Thus, the core of the apple consists of five carpels, with two seeds within each. In the medlar, the upper ends of the carpels are exposed, imparting a singular appearance to the fruit. The structure of the ovary is often very intricate, and therefore will only be referred to when possessing some striking peculiarity.

(c.) Stamen.-Around the pistil are the stamens. (Plate II. Fig. 7, 8, 9.) The stamen consists of a thread called the filament (Fig. 4 a.), upon which is a double vessel called the