Description from Flora of China
Herbs perennial. Leaves dentate, reduced upward, bractlike. Verticillasters ± headlike, in panicles; peduncle sometimes present; bracts linear to needlelike, to as long as calyx. Calyx tubular, 13-veined, sometimes constricted at middle, swollen on 1 side at base, straight or slightly curved, throat sparsely hairy, limb 2-lipped; upper lip 3-toothed, teeth ciliate, apex mucronate; lower lip longer, 2-toothed. Corolla purple-red, reddish, or white, 2-lipped; tube exserted, gradually dilated upward to throat, with 2 rows of hairs, puberulent; upper lip straight, apex emarginate; lower lip 3-lobed, lateral lobes entire; middle lobe larger, emarginate or entire. Stamens 4, anterior 2 longer than posterior 2, reaching upper corolla lip, included or slightly exserted, posterior stamens sometimes rudimentary; anther cells 2, divaricate, ± obliquely inserted on dilated connectives. Style apex unequally 2-cleft, anterior lobe lanceolate, posterior lobe indistinct; ovary glabrous. Nutlets ovoid or subglobose, less than 1 mm in diam., glabrous, areolae small, basal.
About 20 species: Asia, Europe; 11 species in China.
Closely allied to Calamintha; many species are poorly defined.