Hybrid origins Citrus trees are
angiosperms, and most species are almost entirely
interfertile. This includes
grapefruits,
lemons,
limes, oranges, and many
citrus hybrids. As the interfertility of oranges and other citrus has produced numerous hybrids and
cultivars, and
bud mutations have also been selected,
citrus taxonomy has proven difficult. The sweet orange,
Citrus x sinensis, is not a wild fruit, but arose in
domestication in East Asia. It originated in a region encompassing
Southern China,
Northeast India, and
Myanmar. The fruit was created as a cross between a non-pure
mandarin orange and a hybrid
pomelo that had a substantial mandarin component. Since its
chloroplast DNA is that of pomelo, it was likely the hybrid pomelo, perhaps a pomelo
BC1 backcross, that was the maternal parent of the first orange. Based on genomic analysis, the relative proportions of the ancestral species in the sweet orange are approximately 42% pomelo and 58% mandarin. All varieties of the sweet orange descend from this prototype cross, differing only by mutations selected for during agricultural propagation. The
citranges are a group of sweet orange x
trifoliate orange (
Citrus trifoliata) hybrids. of
mandarin and
pomelo. Large-scale cultivation started in the 10th century, as evidenced by complex irrigation techniques specifically adapted to support orange orchards. At Versailles, potted orange trees in solid silver tubs were placed throughout the rooms of the palace, while the Orangerie allowed year-round cultivation of the fruit to supply the court. When Louis condemned his finance minister,
Nicolas Fouquet, in 1664, part of the treasures that he confiscated were over 1,000 orange trees from Fouquet's estate at
Vaux-le-Vicomte.
To the Americas Spanish travelers introduced the sweet orange to the American continent. On his second voyage in 1493,
Christopher Columbus may have planted the fruit on
Hispaniola. Subsequent expeditions in the mid-1500s brought sweet oranges to South America and Mexico, and to Florida in 1565, when
Pedro Menéndez de Avilés founded
St Augustine.
Spanish missionaries brought orange trees to Arizona between 1707 and 1710, while the
Franciscans did the same in San Diego, California, in 1769.
Florida farmers obtained seeds from New Orleans around 1872, after which orange groves were established by grafting the sweet orange on to sour orange rootstocks. The 1870s saw the introduction of improved fruit varieties. In 1873,
navel orange plants from Brazil were distributed by the U.S. Department of Agriculture.
Luther C. Tibbets and
Eliza Tibbets successfully cultivated these in Riverside, leading to widespread planting of the sweet, seedless navel orange, which became the backbone of the California citrus industry. The
Valencia orange, introduced in 1876, matured in summer and fall, complementing the winter-ripening navel and providing oranges year-round. The completion of major railroads (
Southern Pacific in 1877, and the
Santa Fe in 1885) and the introduction of ventilated boxcars revolutionized distribution, opening national markets and triggering a planting frenzy in southern California. By 1885, the number of citrus trees in California had grown from 90,000 (in 1875) to 2 million, and to 4.5 million by 1901. The 1890s brought pest control advances (spraying, fumigation) and frost protection (heaters, later wind machines). The University of California established its
Citrus Experiment Station in 1907, supporting research and innovation. Cooperative marketing emerged with the formation of the California Fruit Growers Exchange in 1905, later known as
Sunkist Growers Inc., which helped standardize and market California citrus worldwide. By the 1980s, California was the second largest orange producer in the U.S., after Florida. == Etymology ==