Description from Flora of China
Plants perennial herbs or subshrubs. Roots often thickened, woody. Leaves dentate. Verticillasters (4-)6-flowered, separate, in long thyrses; bracts shorter than pedicels, circular to oblate, margin entire. Calyx tubular to broadly tubular, tinged with brilliant colors, 2-lipped; upper lip ovate to oblate, scarious, decurrent into tube, margin reflexed; lower lip 4-toothed, teeth awned to needlelike, anterior teeth longer than lateral ones; fruiting calyx enlarged, conspicuously 10-veined. Corolla white or reddish to purple, 2-lipped; tube exserted, straight or incurved, obconical; upper lip 3- or 4-lobed; lower lip entire, concave. Stamens 4, anterior 2 longer, declined, included or slightly exserted; filaments separate, edentate; anthers 1-locellate. Style globose, apex entire or 2-cleft. Disc produced, fingerlike in front. Nutlets ovoid or subglobose, minutely tuberculate, glabrous.
About 45 species: Africa, Asia, Australia; three species in China.