Annual or perennial herbs; branches quadrangular, mainly from base (in Victoria), hairs simple. Leaves petiolate, opposite, simple, crenate, toothed or lobed. Inflorescences leafy, thyrse-like with sessile c. 7-flowered cymes in bract-axils, flowering internodes apparent or hidden by successive cymes. Calyx 5-lobed, lobes subequal; corolla 2-lipped, abaxial lip with median lobe oblong-spathulate, lateral lobes short and broad, adaxial lip narrowly obovate and hooded, entire or bilobed; stamens 4, fertile, usually enclosed in hooded adaxial corolla-lip, inserted in throat of corolla-tube, anthers with both locules fertile, locules very strongly divergent; style gynobasic, stigma bifid. Mericarps 3-keeled.