Annual or perennial herbs or shrubs, rarely trees or lianes (neither in Australia). Leaves alternate, opposite or whorled, simple, entire, toothed or pinnatifid; stipules minute or absent. Inflorescence usually a terminal spike or raceme, or flowers solitary and axillary; bracts usually leaf-like, present or absent. Flowers actinomorphic or zygomorphic, usually bisexual; hypanthium often prolonged above ovary; sepals usually 4 or 5, valvate, often caducous; petals as many as sepals, truncate to emarginate, often conspicuous, sometimes absent; stamens usually twice as many as petals, often in 2 whorls, anthers basifixed or dorsifixed, longitudinally dehiscent; ovary inferior, 1–7(usually 3–5)-celled; stigma capitate or lobed. Fruit usually a loculicidal capsule, rarely a berry or nut; seeds usually numerous, sometimes bearing a coma; endosperm absent.
17 genera with about 650 species, widespread throughout temperate and tropical regions; 5 genera (2 native) and c. 37 species (17 native) in Australia.