grapefruit, pomelo, or pummelo, citrus fruit (Citrus paradisi) of the family Rutaceae (orange family). The grapefruit is so named because it grows in grapelike bunches. The large globular fruit weighs from 1 to 5 lb (0.45-2.27 kg). It is believed that the progenitor of the grapefruit was the pomelo (C. maxima), native to and long a popular fruit in India and other parts of Asia. The pomelo (also called shaddock, for the man who first took it to England as a curiosity) was introduced into the West Indies, where it is thought that a seedling sport or mutation resulted in the grapefruit. Brought to Florida in 1809, the grapefruit had become an important commercial product of that state by the turn of the century. It is now grown in many varieties—chiefly in Florida, Texas, and California in the United States and also in some Mediterranean countries. The tree, an attractive evergreen, is usually propagated by budding. Like other citruses, it is prey to frost and hybridizes easily; the tangelo is a cross between the grapefruit and the tangerine. Grapefruits are classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Rutaceae.

Tree (Citrus paradisi) of the rue family and its edible fruit. It originated in the West Indies (probably Jamaica) before being brought to the New World mainland. The shiny, dark green foliage is very dense. The large white flowers are borne singly or in clusters. Lemon-yellow when ripe, the fruit is 4–6 in. (100–150 mm) in diameter, about twice as large as a medium-size orange. The mildly acidic pulp—juicy and light yellowish, pink, or red—is an excellent source of vitamin C. It is popular as breakfast fruit in various parts of the world.

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