Herbs annual, climbing, hispid. Leaves alternate. Pedicel short or absent. Flowers solitary or fascicled at leaf axils. Calyx 5-parted, 2-dentate between lobes, strongly enlarged in fruit, bilaterally compressed, becoming somewhat clamshell-shaped, with distinct reticulate venation, irregularly emarginate-serrate; lobes unequal. Corolla violet or white, tubular; throat appendaged; limb 5-parted. Stamens included; filaments extremely short; anthers short oblong. Ovary 4-parted. Style included; stigma capitate. Gynobase subulate. Nutlets nearly flat, bilaterally compressed, densely white tuberculate, apex obtuse; attachment scar near apex adaxially. Seeds vertical; cotyledons ovate, complanate.

One species: Asia, Europe.