Perennial shrubs or annual or perennial herbs, glabrous, hairy and/or viscid. Leaves basal or cauline, sessile or petiolate, entire to pinnatipartite, usually with axillary hairs. Inflorescence racemose, sometimes a thyrse, spike or subumbel, or flowers solitary. Flowers strongly zygomorphic; bracteoles present or absent; sepals 5, free; corolla shortly tubular, 2-lipped, often with blunt outgrowths inside, sometimes auriculate, yellow to white or rarely pinkish-mauve or blue; corolla-lobes unequal, winged; stamens free, epigynous, anthers free; ovary inferior, incompletely 2-celled, ovules few-many; style simple or 2–4-fid, glabrous or villous, indusium 2-lipped, c. horizontal, with long bristles on lips, stigma entire to emarginate. Fruit usually a 2- or 4-valved capsule, rarely a nut or drupe; seeds flat, usually winged.
About 199 species; 1 species endemic to Java, 198 in Australia.
In the following key and descriptions, where plants have a bracteole along the peduncle/pedicel, the peduncle is measured to the bracteoles, and the pedicel from the bracteoles to the base of the calyx.