Fls perfect, regular or nearly so; solitary, or in cymes or racemes. Sepals 2, petals (4)-5-(6) rarely 0; stamens 5-10-(20); styles 2-8. Capsule unilocular; placentae basal; seeds 1- ∞ with cop. endosperm. Herbs with ± succulent us. opp. and exstipulate lvs. About 20 genera and 240 spp.; subcosmopolitan.

Annual to perennial herbs. Lvs exstipulate, often with axillary hairs, usually fleshy or succulent, simple, entire; basal lvs rosulate; stem lvs opposite or alternate. Infl. a terminal raceme, cyme, or panicle, or fls solitary. Fls hypogynous or perigynous, ☿; calyx zygomorphic; corolla actinomorphic. Sepals 2, free or connate. Petals (4)-5-(6), free or united at base. Stamens 3-many. Ovary of (2)-3-(8) fused carpels, 1-locular; placentation basal. Stigmas (2)-3-(4); style 1. Fr. a capsule dehiscing by usually 3 valves, or circumscissile. Seeds usually black, smooth, sometimes tuberculate; embryo curved.