Onion

Onion, Herbaceous biennial plant (Allium cepa) of the family Alliaceae, probably native to southwestern Asia but now grown worldwide, and its edible bulb. Among the hardiest and oldest garden vegetable plants, onions bear a cluster of small, greenish white flowers on one or more leafless stalks.

They're rich in chemicals that can help protect your heart, lower your risk of some cancers, and make it easier for your body to make insulin. Onions are also one of the greatest vegetable sources of quercetin, a plant compound with many health benefits.

Onions belong to the Allium family of plants, which also includes chives, garlic, and leeks. These vegetables have characteristic pungent flavors and some medicinal properties. Onions vary in size, shape, color, and flavor. The most common types are red, yellow, and white onions.