Erect or climbing shrubs, rarely trees or herbs, juice often milky. Leaves opposite or whorled, very rarely alternate, simple and entire; stipules wanting. Flowers regular, hermaphrodite, usually in axillary or terminal cymes. Calyx inferior, 4-lobed or -partite; lobes imbricate, often glandular at the base. Corolla gamopetalous, hypogynous, funnel- or salver-shaped; tube often hairy or scaly within; lobes 5, rarely 4, spreading, usually contorted in the bud. Stamens 5, rarely 4, inserted on the tube of the. corolla; filaments short; anthers often sagittate, either free or connate and adhering to the stigma; pollen granular. Ovary superior, usually composed of 2 carpels connate only by their styles, but in one tribe the carpels are wholly combined into a 2-celled ovary with axile placentas or into a 1-celled ovary with 2 parietal placentas; ovules 2 or several or many; style single or separated at the base only, thickened above; stigma entire or 2-fid, often constricted in the middle. Fruit generally of 2 follicles opening along the inner edge, sometimes a drupe or berry. Seeds various, often with a tuft of silky hairs; albumen generally present; embryo straight, radicle usually superior.

A large order, abundantly represented in the tropics of both hemispheres, less plentiful in extra-tropical warm, regions, and decidedly rare in the temperate zones. Genera about 100; species under 1000. The order includes many poisonous plants, some (as the ordeal-tree of Madagascar, Tanghinia venenifera) being exceedingly virulent. Others are employed medicinally as drastic purgatives or febrifuges. A few species yield indiarubber, but on the whole the family is not of much economic importance. The flowers are often of considerable beauty, and many genera are cultivated in gardens or greenhouses. The single New Zealand genus extends through Australia to India and Ceylon.