Description from Flora of China
Herbs, decumbent to erect, with cystoliths. Leaves petiolate; leaf blade margin entire. Inflorescences axillary or terminal spikes, secund or 4-sided, sometimes reduced to a single flower; bracts 2- or 4-ranked but usually only 2 ranks fertile, homomorphic or heteromorphic, usually imbricate, margin usually scarious or hyaline; bracteoles similar to bracts or narrower. Calyx deeply 5-lobed; lobes equal or subequal. Corolla small; tube basally cylindric, distally ± expanded; limb 2-lipped; lower lip spreading, 3-lobed; upper lip erect, rugula (stylar furrow) present, margin entire to emarginate; lobes ascending cochlear in bud. Stamens 2, inserted in corolla throat; anthers 2-thecous; thecae subequal in size, superposed, lower one white spurred at base. Ovary with 2 ovules per locule; stigma entire or slightly 2-cleft. Capsule shortly stalked, ovoid or oblong, 4-seeded; retinacula present; septa (with attached retinacula) separating from inner wall of mature capsule. Seeds compressed, verrucose, lacking trichomes.
About 50 species: Old World tropics and subtropics; 16 species (12 endemic) in China.
(Authors: Hu Jiaqi (胡嘉琪 Hu Chia-chi), Deng Yunfei (邓云飞); Thomas F. Daniel)