Nobody has ever found the common onion growing truly wild
The common onion is the most widely grown member of its genus, yet it is known only from cultivation; its wild ancestor has never been identified. Its nearest living relatives grow in Turkmenistan and Iran. Even the shallot turned out, in 2011, to be just a variety of onion.
Allium cepa, the bulb or common onion, was formally described by Carl Linnaeus in his Species Plantarum of 1753. Its close relatives include garlic, leeks, chives and scallions, and other food plants also go by the name onion, such as the Japanese bunching onion, the tree onion and the Canada onion. Plants escaped from gardens have established themselves in some regions, but no genuinely wild population is known. Botanists place its closest wild kin in Central Asia and Iran, notably Allium vavilovii from Turkmenistan and Allium asarense from Iran.
The names are an etymological tangle. Cepa is the accepted Latin for onion, while Allium was the classical Latin word for garlic. Cepa echoes through the Spanish cebolla, Italian cipolla and Polish cebula, and the English chive comes from Old French chive, itself from cepa.
An onion is a biennial usually grown as an annual, reaching 15 to 45 centimetres. Its hollow, bluish-green leaves fan out from the base, and when days reach a certain length the bulb starts to swell: it is a squashed underground stem wrapped in fleshy scale leaves around a central bud, storing food in the leaf bases. In autumn the foliage dies back and the outer layers dry and turn papery, which is the cue to harvest. Left in the ground, the bulb sends up a tall hollow stalk the next spring, crowned by a round cluster of white flowers with parts in sixes, followed by glossy black, triangular seeds.
Most cultivated onions belong to the common onion group. A second, the aggregatum group, includes shallots and potato onions, which form several bulbs instead of one. Growers battle the onion fly, the onion eelworm and rot-causing fungi. In the kitchen onions go raw into salads, cooked into savoury dishes and pickled or made into chutney, and chopping them releases chemicals that irritate the eyes.
Source: Onion
