Herbs, annual or perennial. Stem sometimes woody at base, simple or dichotomously branched. Stipules filiform. Leaves crowded or almost whorled apically on stems, even-pinnate; petiole basally swollen; leaflets opposite, sessile; leaflet blade apices rounded and mucronate; apical leaflet blade reduced to an awn. Inflorescences umbellate, pedunculate or sessile. Sepals lanceolate, persistent in fruit, apex acuminate. Petals yellow, white, or rarely purple. Ovary subglobose. Capsule ovoid to oblong, loculicidally dehiscent, sometimes splitting to base into 5 spreading valves, each valve with several seeds. Seeds brown, often with small tubercles.

About 50 species: tropical and subtropical regions of the world; three species in China.