Climbers with twining stems, sometimes glaucous; sap milky. Leaves opposite, with glands at base of lamina, petiolate. Inflorescences of few-flowered pedunculate cymes beside upper leaf-axils, or flowers solitary. Flowers pedicellate; sepals large and leafy; corolla campanulate, tube inflated at base, bearing a corona of 5 broad obtuse scales inserted at or below the middle, corolla-lobes shorter than tube, spreading; gynostemium short, broad, included in corolla-tube; staminal corona absent, pollinia 2 per anther, pendent; style head with 2 long slender apical segments. Follicles broad-ovoid; seeds many, with a silky coma.
2 or 3 species, in South America; 1 species naturalised in Australia.