Herbs or low shrubs. Petioles articulate at base; ocrea often laciniate. Flowers axillary, solitary or in small clusters, sometimes forming lax leafy spikes. Perianth (4- or)5-parted, not enlarged in fruit. Stamens 5-8, reduced in number in outer whorl; filaments, especially the inner, strongly dilated at base.

Between 50 and 80 species: worldwide; 16 species (one endemic) in China.