RUTACEAE

family of flowering plants belonging to the order Sapindales and valuable as a source of edible fruit and as ornamentals. Known as the citrus, or rue, family, the Rutaceae includes woody shrubs and trees (and a few herbaceous perennials) and consists of 160 genera and 1,700 species distributed throughout the world, especially in warm temperate and tropical regions. The largest numbers are found in Africa and Australia, often in semiarid woodlands. The flowers are generally perfect (containing both male and female reproductive organs in the same flower) or sometimes unisexual. They are arranged in inflorescences, which facilitates pollination by insects such as small flies and bees. The flowers are conspicuous for their colour, fragrance, and nectar. The fruits of the family are various, consisting, for example, of capsules (genus Ruta), follicles (Zanthoxylum), drupes (Amyris), berries (Triphasia), samaras (hop tree), and schizocarps (Helietta). A citrus fruit is actually a modified berry. The family contains economically important fruits. Citrus species include the lemon (Citrus limon), sour orange (C. aurantium), sweet orange (C. sinensis), lime (C. aurantifolia), tangerine and mandarin orange (C. reticulata), grapefruit (C. paradisi), and citron (C. medica). All of these are grown for their fruits. Other regionally important fruits are the kumquat (Fortunella), bael (Aegle), elephant apple (Limonia acidissima), and Japanese pepper (Zanthoxylum piperitum). Among the ornamentals are Poncirus, a spiny hedge shrub of temperate regions, and Japanese skimmia (Skimmia japonica) and Chinese skimmia (S. reevesiana), which have attractive white flowers and red berries. Orange jessamine (Murraya exotica, or paniculata) is native to Southeast Asia and is widely grown in the tropics as an ornamental. Perhaps the most unusual is the burning bush (Dictamnus albus), a nonwoody poisonous perennial herb that has attractive white flowers. The ethereal oil glands can be squeezed, releasing the oil, which when expressed into the air can be ignited by a match.