Cultivated ornamentals, many species yield bitter principles used medicinally and in flavorings. There is a glandular disk at the base of the G, and flowers have parietal placentation. Inflorescence is cymose. Fruit a dehiscent septicidal capsule, rarely a berry. Seed small with copious oily endosperm and a straight embryo.
Plants are usually rhizomatous.
Leaves opposite and simple. Stipules are absent.