Description from Flora of China
Herbs, prostrate at base. Leaves numerous, petiolate, margin dentate. Verticillasters ca. 6-flowered, in axillary or terminal spikes; floral leaves generally reduced to ovate bracts slightly longer than calyx. Calyx tubular-campanulate, pouched in fruit, straight or curved downward, herbaceous, 10-15-veined; teeth 5, subequal or limb ± 2-lipped and upper lip 3-toothed and lower lip 2-toothed. Corolla tube nearly included or much exserted, straight or curved downward, slightly dilated at apex, 2-lipped; upper lip short, straight, emarginate or 2-lobed; lower lip longer, spreading, 3-lobed, lobes ovate; middle lobe largest, entire or 2-lobulate. Stamens 4, anterior 2 longer, reaching upper corolla lip; anther cells 1 or 2, divaricate, apex confluent if 2. Style apex 2-cleft, posterior lobe short. Disc shallowly cupulate, crenate. Nutlets obovoid to oblong-ovoid, densely scaly.
About 30 species: Asia, Africa; two species in China.