105. Labiatae.—Mint Family.
One of the most natural groups of plants in the vegetable kingdom. Its members being so uniform, it would seem as if all of its species could be comprehended in a single genus; hence the characteristics of its different genera are very difficult to make out.
DESCRIPTION.—Herbs with opposite or whorled leaves. Flowers in axils of leaves or bracts, solitary or clustered cymes, scattered or crowded into spikes. Calyx sometimes 2-lipped, upper lip bifid, lower trifid, sometimes subregular. Corolla monopetalous, bilabiate, the upper lip entire or emarginate, the lower 3-lobed, sometimes bell- or funnel-shaped, with 4 subequal lobes (Mentha). Stamens 4, inserted on the corolla tube, didynamous (2 long and 2 short), or 2 by the abortion of the 2 tipper (Lycopus, Salvia, Rosmarinus). Ovary 4-lobed. Ovules 4. Style simple, rising from the base of the ovarian lobes. Fruit separating into 4 akenes. Stem quadrangular, with volatile oil secreted in vascular glands.
General Description of Drugs of the Order
In most instances the drug consists of dry herbs composed of leaves, or leaves and tops, with portions of stem, branches, and flowers. These are usually broken and intermixed. Odor aromatic, due to the secreted volatile oil; some species hold in solution a solid hydrocarbon (stearopten) analogous to camphor. Taste aromatic, pungent, cooling, and bitterish (marrubium). The odor and taste are frequently sufficient to distinguish the different drugs, but a knowledge of the size, shape, and marginal character of the leaves and their texture, and the character of the stem and branches is sometimes quite useful in the identification of the various drugs derived from the order.