Diffuse, annual or perennial, often trailing or ascending, usually glabrous and fleshy herbs. Leaves simple, alternate or opposite, sometimes subopposite; the uppermost crowded to form a sort of involucre below the flowers, flat or terete-semiterete, fleshy; stipules scarious or modified into a bunch of hairs, rarely absent. Inflorescence a terminal fasciculate cyme or flowers solitary ter¬minal, surrounded by a whorl of leaves. Flowers bisexual, actinomorphic, sessile, perigynous, usually 5-merous, showy, variously coloured; bracts entire or modified into hairs. Sepals 2, fused at the base to form a very short tube partly adnate to ovary and the lobes caducous. Petals 4-6, free or united at the base, inserted on rim of calyx tube, marcescent. Stamens 4-many, free or united at the base, inserted on rim of calyx tube and adnate to petals, rarely epipetalous. Carpels usually more than 3, syncarpous; ovary ovoid, half adnate to calyx, semi-inferior; ovules many, campylotropous; style with 3-8 elongated and radiating stigmas. Fruit brittle with thin membranous wall, subglobose to globose or oblong-conical, unilocular capsule, with transverse (circumscissile) dehiscence. Seeds numerous, minute, reniform or lenticular, testa shining, aculeate, tuberculate or somewhat papillate.