The onion is an edible bulb produced by a biennial plant with the scientific name Alium cepa. The word onion is from the Latin word unio, meaning "single" or "one"; the name refers to the fact that the onion plant, unlike other plants of the same genus, only produces one bulb. The upper part of the onion plant is a set of leaves growing inside each other. The lower parts of these leaves become very thick, and the edible bulb, which is enclosed in a thin, papery covering made up of dried outer leaves, forms just under or above the ground at the base of the leaves. Small, white flowers grow in rounded clusters at the top of the plant. Cultivated onions are typically white or red in color. Scallions are young onions that are harvested before they form bulbs.
Although onions are not particularly high in vitamins and minerals, they are high in antioxidants and sulfur-containing compounds. Studies have shown onions to have a positive effect on heart health by helping the blood carry more oxygen. There is also some evidence that onions can help with the treatment of gastric ulcers and some cancers, as well as help prevent the onset of osteoporosis. Unfortunately, the same sulfur compounds that give onions their potential health benefits are the same ones that cause your eyes to water when you cut into them. This tearing effect can be greatly lessened by cutting onions in water.
Onions were originally native to Central Asia, but are now grown around the world. They have been cultivated for at least 5,000 years, but it is not known where or when they were first domesticated. The ancient Egyptians prized onions so much they buried them with their pharaohs and used them in many religious rituals, and Roman soldiers carried onions with them across the Roman Empire. Today, China, India, the United States, Canada, Russia and Spain lead the world in onion production. In the United States, the majority of the commercial onion crop is grown in Washington, Idaho, Oregon, California, Texas and Georgia. The average American consumes 20 pounds of onions every year.
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This page was last updated on 04/19/2012.