Perennial herbs, suffrutices or shrubs. Young branches, undersides of leaves and corollas with sessile glands. Leaves often held in a V and reflexed; margin entire. Calyx 2-lipped with 2 entire, broadly rounded lips, enlarging in fruit. Corolla with a 3-lobed lower lip and 2-lobed upper lip, dark reddish-brown to blackish-purple. Stamens 4, normally exserted. Style 2-lobed. Nutlets with a well-developed wing on the dorsal side.