Erect, perennial herbs or subshrubs. Leaves opposite or upper ones alternate. Inflorescence of lateral or terminal cymes. Calyx 5-lobed, eglandular inside. Corolla campanulate or cylindrical, 5-lobed, lobes overlapping to the right in bud, pubescent or densely glandular inside, with 5 stiff processes at base alternating with stamens and opposite the corolla lobes. Stamens united with stigma; anthers oblong, acute, connective enlarged, membranous; filament short. Disc annular, 5-lobed. Carpels free, ovary subinferior; ovules many; style very short or absent; stigma biconical or sub-globose, 2-lobed. Follicles 2, slender, many-seeded. Seed small, oblong, with a long hairy coma.