Annual or perennial herbs or shrubs, usually with trailing or twining stems, rarely erect (not in Victoria), hairs simple. Leaves simple, rarely compound (not in Victoria), margins entire or deeply lobed, glabrous or hairy, petiolate; pseudo-stipules sometimes present. Inflorescences axillary, cymose, or flowers solitary; bracteoles present. Sepals 5, free, usually unequal, imbricate; corolla usually funnel-shaped or campanulate, entire or slightly 5-lobed, distinct hairy or glabrous mid-petaline bands present; stamens 5, usually more or less unequal, included or exserted, filaments hairy towards the base; ovary 2–4-celled, glabrous, rarely pilose, ovules 2 per cell, style 1, stigma capitate or biglobose. Capsule ovoid or globose, usually splitting longitudinally into 4–6 valves, rarely indehiscent; seeds usually 4–6 per capsule, glabrous or hairy.
About 500 species, from tropical to warm temperate regions; c. 50 species in Australia (20 endemic, 12 naturalized).