Grapefruit, (Citrus paradisi), citrus tree of the Rutaceae family and its edible fruit. The grapefruit probably originated in Barbados as a hybrid of shaddock (Citrus grandis). It became well established as a fruit for home consumption in the islands of the West Indies before its culture spread to the American mainland. Grapefruit has become popular as breakfast fruit in various parts of the world, and production has expanded to most citrus-growing countries, notably the United States, Israel, Cyprus, South Africa, and Brazil. As a source of vitamin C, the grapefruit is exceeded among common fruits only by the orange and lemon.