Erect or ± scandent herbs or undershrubs. Leaves petiolate, simple, thin, with numerous cystoliths on the upper surface, entire to crenulate, acute to acuminate. Flowers shortly pedicellate, of various colours, in loose or compact, simple or compound racemes or spikes; bracts lanceolate, not 4-ranked, acute; bracteoles linear, shorter than calyx. Calyx deeply 5-lobed, lobes equal, linear-lanceolate, hairy, acute or acuminate. Corolla infundibuliform, tube narrow or ventricose, limb subequally 5-lobed, lobes ± orbicular, obtuse, imbricate, patent. Stamens 4, all fertile, didynamous, included; anthers dithecous, oblong, unequal, each lobe muticous or basally minutely beaked. Ovary oblong-cylindrical, hairy, bilocular, each locule 2-ovuled; style basally hairy, stigma minutely 2-fid, or ± capitate. Capsule stipitate, elliptic-oblong, flattened, pubescent, 2-4-seeded. Seeds ± orbicular or angled, compressed, glabrous, on hooked funicles.