Citrus

The many forms of commercial citrus all descend primarily from three original species native to Asia: citron (Citrus medica), an ancestor of the lemon; pomelo (C. grandis), a giant parent of the grapefruit; and mandarin (C. reticulata), which includes tangerines and similar fruits. Citrus cultivation in the area that would become the United States dates from the Spanish exploration and settlement of Florida in the sixteenth century; it reached Louisiana around 1700 and California with the arrival of Franciscan friars in 1769. Since most citrus cannot tolerate temperatures more than a few degrees below freezing, open-air cultivation has generally been limited to warmer areas, but until the second half of the nineteenth century it was not uncommon for the wealthy to grow oranges and lemons in greenhouses.