Annual herbs, glabrous; branches terete. Leaves opposite, petiolate, margin coarsely dentate to lobed. Inflorescence of sessile cymes forming pseudowhorls around upper nodes. Calyx glabrous, broadly funnel-shaped, slightly zygomorphic, obscurely 5-lobed, with the 5 main veins terminated by a short mucro; corolla 2-lipped, abaxial lip with 2 narrow lateral lobes and a broad spathulate median lobe, adaxial lip oblong, hooded, slightly 2-lobed; stamens 4, fertile, inserted in the throat of the corolla-tube, anthers with 2 fertile locules, diverging at near right-angles from the attachment of the filaments, enclosed in a hood of the adaxial lip of the corolla; stigma bifid. Fruit usually falling with calyx intact; mericarps 3-keeled.
4 species, from the Mediterranean region to north-west India; 1 species naturalised in Australia.