Description from Flora of China
Herbs annual or perennial, short pubescent or glabrescent. Leaves alternate. Cymes becoming racemelike after anthesis, ebracteate or rarely with few bracts. Calyx 5-lobed or parted, slightly enlarged or not in fruit. Corolla blue or white, rarely light purple, usually salverform, rarely campanulate or funnelform; throat appendages 5, scalelike; lobes 5, spreading, rotund, margin convolute. Stamens included; anthers ovate to elliptic, apex obtuse. Ovary 4-parted. Style linear; stigma discoid, mucronate. Gynobase flat or slightly convex. Nutlets 4, usually ovate, appressed, lenticular, vertical, smooth, shiny; attachment scar basal.
About 50 species: Africa, Asia, Australia, Europe, North America; five species in China.