citrus fruits, widely used edible fruits of plants belonging to Citrus and related genera of the family Rutaceae (orange family). Included are the tangerine, citrange, tangelo, orange, pomelo, grapefruit, lemon, lime, citron, and kumquat. Almost all the species bearing edible fruits are small trees native to SE Asia, Indonesia, or Malaysia. The citron was introduced to the Mediterranean area from Asia before the advent of Christianity; the others were spread chiefly by the Arabs during the Middle Ages. Introduced throughout Europe during the Crusades, they were brought by Portuguese and Spanish explorers to the West Indies, whence they were introduced into North and South America. Commercially they are now the most important group of tropical and subtropical fruits in the world. The fruits are rich in vitamin C (ascorbic acid), various fruit acids (especially citric acid), and fruit sugar. The rind, which contains numerous oil glands, and the fragrant blossoms of some species are also a source of essential oils used for perfumes and similar products. Citrus fruits can be damaged by freezing temperatures, pests (scale insects, rust mites), and various bacterial, viral, and fungal diseases (e.g., citrus canker, greening, tristeza, and melanose).
See W. Reuther, ed., The Citrus Industry (3 vol., 1968–78); R. W. Ward and R. L. Kilmer, The Citrus Industry (1989).