onion

onion

Onion, plant of the family Liliaceae (lily family), of the same genus (Allium) as the chive (A. schoenoprasum), garlic (A. sativum), leek (A. porrum), and shallot (A. ascalonium). These onion plants are characterized by an edible bulb composed of food-storage leaves that are rich in sugar and pungent oil, the source of its strong taste. The above-ground green leaves of onion, typically long and tubular, are also eaten.

Onion of all these species is believed to be native to SW Asia and is known to have been cultivated since ancient times. The onion (A. cepa), no longer found wild, is a biennial now grown in many varieties throughout the world as a table vegetable. Common varieties of onion include the strong-flavored red onion, the milder yellow onion, and the bland white onion. Pearl onions are small white onions used for pickling. The large Spanish and Bermuda onions have a delicate flavor.

Onion was grown extensively by the ancient Egyptians, in whose writings onion is mentioned, and was later spread by the Spanish colonists. The more pungent garlic, a perennial, has a bulb consisting of small bulbils called cloves. This part of it is most often used in cooking, chiefly as flavoring; garlic is especially popular in the Mediterranean region and East Asia. Used as a folk remedy for thousands of years, scientific investigation is confirming garlic's usefulness as a blood thinner, antioxidant, and cancer preventive.