Erect, perennial shrubs; branches compressed, reddish. Leaves opposite, usually connate at base, trigonous to triquetrous or subterete, sometimes dentate, glabrous or papillate. Flowers in a many-flowered, often branching inflorescence or solitary, pedicellate, subtended by leaf-like bracts; sepals 5, subequal; petaloid staminodes many, purple to white; ovary inferior, 5-locular; ovules numerous, parietal. Fruit a 5-locular capsule; valves winged; locules remaining partly covered by an elastic, membranous ‘roof’; seeds spherical, reticulate or tuberculate.
About 220 species in southern Africa, 1 naturalised in Australia.