Annual or perennial herbs. Leaves alternate or opposite, often clustered. Flowers solitary or in small clusters (dichasia) opposite leaves, in axils, or terminating branches; perianth segments 5, equal, free; stamens 3–20; staminodes often present; ovary 3–5-locular; styles as many as locules. Fruit a membranous, loculicidal capsule. Seeds with a white caruncle and a slender funicle which largely encircles the seed.
About 12 species in tropical and warm-temperate countries; 3 species in Australia.