Diffusely branching annual or perennial herbs. Leaves alternate or almost opposite, mostly fleshy, flat or terete, with scarious or setaceous stipules, sometimes minute. Flowers mostly terminal, solitary or in clusters, sessile or pedicellate, yellow or purplish. Sepals 2, connate at base, partly united with ovary, caducous. Petals 4-6, free or inserted at top of calyx. Stamens 7 to many, inserted on petals. Ovary 1-celled; placentation central; ovules many in vertical rows; style filiform, 2-8-fid. Capsule membranous, opening by a lid. Seeds reniform, shining, often tuberculate.