orange, name for a tree of the family Rutaceae (rue, or orange, family), native to China and Indochina, and for its fruit, the most important fresh fruit of international commerce. Its physical characteristics (especially the rich citric acid and vitamin content of the fruit) and history of cultivation are similar to those of the other types of citrus fruits, all of which are species of Citrus.
Among the commercially important species of oranges are the sweet, or common, orange (C. sinensis), which furnishes most of the varieties for commercial growing, including the Baiá, or Washington, navel (a winter orange), and the Valencia (a summer orange); the sour, or Seville, orange (C. aurantium), which is grown in the United States chiefly as understock on which to bud sweet orange varieties, although in Europe its fruit is much used in marmalade; the mandarin (C. reticulata or nobilis), or the “kid glove,” or loose-rind, group of oranges, which includes the Satsuma varieties, known for their hardiness, tangerines, and clementines. Oranges hybridize freely. The Temple orange is a cross between a mandarin and a sweet orange; the citrange a cross between the inedible trifoliate orange (C. trifoliata) and a sweet orange; and the tangelo is produced by crossing a tangerine and a grapefruit.
Columbus brought the orange to the West Indies, and it is known that orange trees were well established in Florida before 1565 and were growing in California by 1800. The orange now grows in the warm parts of all continents. Flowers and fruits in all stages of development are on the tree throughout the year, although a large portion of the fruits ripen at one time. The orange is attacked by many insects and fungus diseases and is quite sensitive to frost. If the fruits are picked when still “green” (though fully mature), they must undergo a bleaching or degreening process to bring out the orange or yellow color in their rinds. Some oranges are artificially colored and waxed before marketing.
Most oranges, like other citrus fruits, are consumed fresh or made into juice. The fruit and rind are also much used in marmalade, preserves, flavoring, and confections. Some varieties yield essential oils used in perfume. The flower is a favorite for bridal decoration and is the state flower of Florida. The yellow wood, which is hard and close-grained, is manufactured into small articles.
Orange is classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Rutaceae.