Perennial herbs or subshrubs with slender trailing or running stems. Lvs opposite. Fls solitary in lf axils. Pedicels long. Calyx lobes usually 1/2 length of corolla tube. Corolla funnelform, usually blue or violet, rarely white or pink; tube gradually widening, with a band of hairs above stamen insertion, and a low ridge connecting the lobes at the mouth; lobes oblique, = or > tube, twisted anticlockwise in bud. Stamens inserted at middle of corolla tube; filament flattened, bent abruptly at base, much > anther cells; connective expanded above into flap-like appendage; length of anther cells not more than 2× width. Disc of 2 glands, much < ovary. Carpels 2; ovules 4-8. Stigma without transparent collar at base, with coma of hairs. Follicles cylindric, patent. Seeds glabrous.