LABIATAE. An extensive order of herbs, shrubs, or sub-shrubs, rarely arborescent or scandent, found chiefly in temperate regions of the Old World. Flowers in the axils of leaves or bracts, solitary or geminate, or in clustered centrifugal cymes, which form false whorls by their union in pairs, and are scattered, or crowded into spikes; calyx persistent, tubular, dentate, lobed or two-lipped; corolla gamopetalous; tube evolute, short, or elongated, many-formed; limb four or five-lobed; aestivation imbricate, sometimes bilabiate, the upper lip entire or emarginate, the lower three-lobed, from the upper lip being very short and deeply cleft, sometimes being bell or funnel-shaped, with four sub-equal lobes and sub-equal stamens. Leaves opposite or whorled, with pinnate reticulate nerves, exstipulate. "Labiatae forms one of the most natural groups of plants; the characters of its members are so uniform that it may be called monotypic, as if all the species could be comprehended in a single genus, and the discrimination of its genera is hence often very difficult" (Decaisne and Le Maiout). Many of the genera yield a valuable oil. Basil, Horehound, Hyssop, Lavender, Marjoram, Mint, Patchouly, Rosemary, Sage, Savory, and Thyme, belong to this order. There are about 140 genera and 2600 species. The following are examples: AEolanthus, Anisochilus, Coleus, Cunila, Hyssopus, Lamium, Lophanthus, Perilla, Salvia.