Perennial herbs or subshrubs. Leaves sessile; 3-veined. Inflorescences axillary clusters. Flowers subsessile, 5-merous; calyx campanulate, calyx lobes 5 in outer flowers of cluster, or reduced to 4 or 3 in inner flowers of cluster; corolla tubular to salver-shaped, regularly 5-lobed; stamens 5, base of filaments broadened and with scale-like appendage, small triangular lobe alternates with filaments, anthers oblongoid, connective apiculate; pollen in monads; stigma capitate. Fruit a capsule with persistent calyx and corolla; seeds angular, foveolate.