Herbs or shrubs. Stem pubescent, lanose, or glabrous. Leaves opposite, petiolate. Flowers perfect, arranged in terminal or axillary heads or spikes, flower solitary in axil of a bract, subtended by 2 bracteoles. Tepals 5, erect, membranous, becoming rigid or not after anthesis. Stamens 5; filaments unequal, united to a short cup at base, pseudostaminodes absent or very small; anthers 2-loculed. Ovary ellipsoid or globose; ovule 1, pendulous; style slender; stigma capitate or 2-lobed. Utricles enclosed in perianth, ellipsoid, indehiscent. Seed erect, lenticular, smooth.

About 14 species: Africa, SE Asia; three species (one endemic) in China.