Perennial herbs, sometimes short-lived, glandular-hairy or glabrous. Leaves usually alternate, sessile to petiolate, cauline leaves reduced or absent; stipules absent. Inflorescence a many-flowered terminal cyme or thyrse, or a solitary flower. Flowers usually bisexual, zygomorphic (in Victoria) or more commonly actinomorphic; sepals usually 5, petals usually 5, variously coloured, or absent; stamens 10, rarely 8, filaments linear, sometimes clavate; nectary disc often present; ovary superior to inferior, usually 2-locular; ovules numerous, placentation axile. Fruit usually a 2-valved capsule; seeds many.
c. 370 species from temperate and arctic regions of the Northern Hemisphere; 1 species recorded in Australia.