Annual or perennial, erect, prostrate or climbing herbs, sometimes lignified at the base, woody lianas and erect shrubs, the latter sometimes spiny; pubescent or not, the hairs unbranched. Leaves sessile or petiolate, margins entire to deeply lobed, sometimes highly variable in shape within an individual or a species. Inflorescences axillary or terminal; flowers in one to many-flowered cymes, rarely arranged in a compound thyrse, sometimes apparently solitary, axillary. Bracteoles usually small and filiform but in compact inflorescences sometimes leafy, ovate or lanceolate. Sepals 5, quincuncial, usually unequal, the middle sepal often asymmetric, the exposed half resembling the outer sepals and the enclosed half resembling the inner sepals. Corolla funnel-form or rarely campanulate; margin entire or lobed, rarely ±fimbriate; limb pink, white, purple, blue or rarely yellow, the centre often differently coloured, the throat occasionally with dark marks; usually glabrous except for the midpetaline bands that are pubescent in the upper half in most species. Stamens included, often unequal. Filaments dilated at the base, filiform above, glabrous or with sessile or stalked glands in the dilated part. Anthers +/- equal, oblong to sagitate, rarely broadly oblong, dehiscing longitudinally. Pollen elliposidal, trciolpate.Ovary ovoid, conical or globular, entire or lobed, glabrous or hairy, sometimes densely so. Style one, slender, glabrous or hairy. Stigmas two, filiform or cylindrical. Fruits capsules, dehiscing loculicidally or irregularly. Seeds 1-4, surface smooth, tuberculate, ridged or hairy.