Herbs, rarely basally woody. Stems simple or branched at base. Leaves alternate, large, often crowded below, margin entire or toothed. Flowers in terminal, often secund racemes. Calyx 5-lobed; lobes imbricate. Corolla oblique, tubular-campanulate, often constricted beyond ovary, somewhat ventricose; limb slightly 2-lipped; lower lip 3-lobed, middle lobe longer than lateral lobes; upper lip lobes much reduced, emarginate. Stamens 4, didynamous, included; anthers touching in pairs, locules divaricate, apically confluent. Style 2-lobed. Capsule ovoid, septicidal. Seeds numerous, oblong to subovoid, small, ribbed; seed coat scrobiculate-reticulate.

About 25 species: Asia, Europe; one species cultivated in China.