Annual or perennial herbs or subshrubs. Lvs opposite, mostly sessile or nearly so, entire or toothed. Fls axillary or in terminal racemes, occasionally solitary. Calyx usually of 5 free and equal sepals. Corolla 2-lipped; tube very short, saccate or forming a spur on anterior side; throat closed by a pouch at the base; upper lip 4-lobed; lower lip lobe emarginate or entire. Stamens 4, included, inserted at base of corolla tube; anthers 1-celled, usually cohering around stigma. Capsule laterally compressed, septicidally dehiscent with valves keeled and boat-shaped. Seeds numerous, fairly large, with a membranous wing.