Erect or decumbent, much-branched succulent annuals or perennials; stems terete, sometimes jointed. Leaves opposite, sessile, sometimes shortly connate at base, slender, terete or semi-terete, soon withering and deciduous. Flowers terminal, in cymes or solitary on lateral branches, pedicellate; sepals 5, rarely 4 (but not in Australia); petaloid staminodes and stamens numerous; ovary inferior or slightly superior, 5(4)-locular; ovules numerous, axile. Fruit 5(4)-locular; locules without wings; seeds D-shaped to triangular, laterally compressed, tuberculate.
72 species, endemic in South Africa; 1 species naturalised in Australia.