Description from Flora of China
Herbs perennial. Roots thickened, hispid or strigose. Stem leaves sometimes decurrent. Cymes terminal, becoming paniculate, bracteate. Calyx 5-parted to middle or below; lobes unequal, slightly elongated in fruit. Corolla light purple-red, rarely yellow, tubular-campanulate; throat appendages 5, lanceolate, with papillate glands; limb 5-lobed; lobes triangular to semiorbicular, margin dentate, apex sometimes revolute. Stamens inserted at throat, not exserted; anthers linear-oblong. Ovary 4-parted. Style filiform, usually exserted; stigma capitate. Gynobase flat. Nutlets ovoid, sometimes suboblique, usually granular-tuberculate, reticulate-wrinkled, rarely smooth; attachment scar at base, cupular, finely dentate at margin.
About 20 species: Asia, Europe, cultivated worldwide; one species in China.