Annual or perennial herbs, rarely subshrubs, usually with thin rhizomes or tubers. Leaves opposite, spirally arranged, or alternate, simple, margins crenate, dentate or serrate, teeth often gland-tipped; stipular glands sometimes present. Flowers bisexual, zygomorphic, in axillary clusters or racemes, or solitary; pedicle usually twisted through 180°, presenting flower upside-down; sepals 3 or 5, the lowermost larger and petaloid, usually spurred; petals 5, free or the lower 4 petals united in lateral pairs; stamens 5, anthers fused in a ring surrounding the gynoecium, falling off in one piece before the stigma becomes receptive, dehiscing by longitudinal slits or pores; ovary superior, 4- or 5-locular, ovules 2–many per locule; style 1, short, stigmas 1–5. Fruit a berry or fleshy loculicidal capsule with explosive dehiscence; seeds without endosperm.
2 genera with c. 1,000 species from Europe, Africa, Asia, and North America; 3 species naturalised in Australia.