rape, in botany, annual herb ( Brassica napus ) of the family Cruciferae (mustard family), belonging to the same genus as the cabbage, the mustard plant, and the turnip (which it resembles in appearance). The origin of the rape is uncertain, and it is now known only as a cultivated plant. The seeds have been valued since ancient times for their oil content (30% to 45%). The oil, expressed or extracted by solvents, is used for lubricating, cooking, and illuminating purposes, for fuel, and for the manufacture of soap and synthetic rubber. Canola oil is also obtained from rape and is becoming widely used as a cooking oil because it has none of the deleterious effects of cholesterol and is completely digestible. A cake made of the seed residue is a valuable stock feed and a good nitrogenous fertilizer. Major producing areas include China, India, and Europe; the United States is one of the chief importers of the oil. Rape is also grown for forage, particularly for hogs; it is also sown as a cover crop (e.g., in orchards). Rape seed is used in birdseed mixtures. In North America, the plant is cultivated chiefly for forage—especially in the northern states and in Canada, because it can be grown as a winter-hardy biennial. Other similar species of Brassica are sometimes cultivated, especially in Asia for oil production. Rape is classified in the division Magnoliophyta, class Magnoliopsida, order Capparales, family Brassicaceae (Cruciferae).
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