Annual to perennial, erect or creeping, mostly branched herbs or shrubs, occasionally woody at the base, often with a tuberous or swollen main root, occasionally rooting at the nodes. Leaves spirally arranged to opposite, subsessile, occasionally with axillary hairs or scales (in Mal. only in Portulaca), nervation pinnate or reticulate. Flowers bisexual, actinomorphous (occasionally cleistogamous), in axillary and/or terminal thyrsi, dichasia, in terminal capitules or solitary (terminal or axillary). Bracts leaf-like or membranous. Sepals 2 (4-8 in extra-Mal. Lewisia and Grahamia), boat-shaped, deltoid to obovate at base shortly connate and confluent with petals and stamens. Petals (3-)4-6(-8), mostly obovate and unequal, shortly connate. Stamens (l-)3-∞, in 1-∞ ± distinct whorls; filaments basally shortly connate; anthers 2- or 4-celled, dorsifixed, dehiscing lengthwise. Ovary superior or half-inferior, originally 2-20-celled, soon becoming 1-celled; style with 2-20 mostly papillous arms. Ovules 4-∞ on a central, dendroid placenta, campylotropous. Capsule 3-7-valved or with a caducous operculum, occasionally surrounded by the persistent calyx. Seeds 1-∞, smooth or ornamented, kidneyshaped to ± globular, laterally compressed, mostly with a caruncle. Embryo curved, almost filling the ripe seed. Distribution. About 15 genera with possibly 200 spp. Cosmopolitan, with some tropical species occurring as adventives in temperate regions. In Malesia 4 genera with 11 spp.