The most frequently grown member of the genus Allium is the onion, also referred to as the bulb onion or common onion (Allium cepa L., from the Latin cepa, meaning “onion”). The shallot is a botanical variant of the onion, which until 2010 was recognized as a distinct species. [2] [3]: 21 Its relatives include chive, leek, garlic, and scallion. [4]
Other species in this genus that are grown for food and go by different names like “onions” include the Japanese bunching onion (Allium fistulosum), the tree onion (A. proliferum), and the Canada onion (Allium canadense). Numerous Allium species are referred to as “wild onions,” but only A. cepa has been cultivated. Although escapes from cultivation have taken root in some areas, its original wild form is unknown. [5] Even though onions are typically biennial or perennial plants, they are typically maintained as annuals and harvested during their first growing season.
When a specific day-length is reached, the onion plant’s bulb at the base of the plant starts to swell and has a fan of hollow, bluish-green leaves. The underground stems of the bulbs are compressed and shortened, and they are covered with mushy modified scales (leaves) that enclose a central bud at the stem’s tip. The foliage dies down in the autumn (or in the spring, in the case of overwintering onions), and the outer layers of the bulb become drier and more fragile. Onions are now ready for use or storage after the crop has been harvested and dried. In particular, the onion fly, the onion eelworm, and several fungi that might cause rotting are likely to assault the crop. A. cepa cultivars that yield many bulbs include shallots and potato onions.
All around the world, onions are grown and used. They can be consumed raw or used to produce pickles or chutneys, but they are typically served cooked, as a vegetable or as a component of a prepared savoury dish. When chopped, they have a strong flavor and contain certain chemicals that might irritate the eyes.