Erect or scandent herbs, rarely woody at base, branches quadrangular. Upper leaves exstipulate, lower smaller in size, 4-6 in whorl, rarely opposite, linear-lanceolate, rarely ovate or obovate. Inflorescence of terminal and axillary subumbellate and fasciculate cymes or thyrses, mostly subtended by bracts and bracteoles. Flowers small. Calyx tube ovoid, globose or didymous, limb absent, rarely minutely 4-5-dentate. Corolla-tube funnel-shaped, or subcampanulate, throat naked, lobes 4-5 rarely 3, inserted in the corolla-tube or throat, filaments short, anthers short, exserted, didynamous. Disc inconspicuous. Ovary 2-loculed, styles two or bifid; stigma capitate-globose. Ovules solitary. Fruit a small, didymous, dry, indehiscent mericarps. Seed adhering to the pericarp, testa membranous, albumen hard, embryo curved, cotyledons leafy, broad and thin.