Herbs or shrubs, often provided with hooked, viscid, or stinging hairs. Leaves alternate or opposite, entire, lobed, or pinnatifid. Stipules wanting. Flowers hermaphrodite, actinomorphic, solitary or in cymes, yellow, rarely white or red; peduncles often opposite the leaves. Sepals 5 (or 4—7), persistent, imbricate. Petals as many as the sepals. Stamens numerous, in epipetalous clusters, or rarely 2—5. Staminodes alternating with the petals or wanting. Ovary inferior, 1- (or 2—3) celled; style entire or 2—3-cleft; stigma pointed or capitate. Ovules many, on 3—7 parietal placentas or only one ovule attached at the top of the ovary, anatropous. Fruit a capsule, 1—3-celled, opening by 3—7 valves at the apex or with longitudinal dehiscence. Seeds various in form and size. Endosperm present or wanting. Embryo straight or curved. About 250 species in 15 genera, mainly in tropical and subtropical America; only one genus in Africa.