Annual, biennial, or perennial herbs, rarely low, spiny shrubs or cushion plants. Leaves exstipulate, more or less joined at the base, suborbicular to linear or setaceous. Inflorescences cymose, axillary or more often terminal, few- or many-flowered, flowers sometimes solitary. Sepals 5 (or 4), free, herbaceous with a narrow or wide scarious margin, persistent, 1- or 3-nerved with a prominent midrib. Petals 5 (0), white to pinkish, entire or slightly emarginate. Stamens mostly 10, the 5 outer ones with basal glands. Ovary of 3 (2-5) carpels with as many short styles. Capsule opening with twice as many teeth or, more rarely, bifid valves. Seeds usually numerous, black, rarely reddish brown, spherical to reniform, tuberculate.
Asia-Tropical: East Africa: present South America: present
About 150 species widely distributed on the northern hemisphere from the arctic to the subtropical zone, on the southern hemisphere in montane regions in East Africa and South America. In Malesia one species.