Editing Onion (section)

{{short description|Bulbous vegetable grown for food}}
{{about|the plant}}
{{Redirect|Onions|the surname|Onions (surname)}}
{{pp-vandalism|small=yes}}
{{Use British English|date=July 2023}}
{{Use dmy dates|date=October 2023}}
{{cs1 config|name-list-style=vanc|display-authors=3}}
{{Speciesbox
|taxon=Allium cepa
|parent=Allium subg. Cepa
|image=Mixed onions.jpg
|image_caption=A display of commercially-grown [[bulb]]s, including red and yellow cultivars.
|authority=[[Carl Linnaeus|L.]]
|synonyms=
{{collapsible list|bullets=true
|title=<small>Species synonymy</small>
|''Allium angolense'' <small>Baker</small>
|''Allium aobanum'' <small>Araki</small>
|''Allium ascalonicum'' <small>auct.</small>
|''Allium ascalonicum'' var. ''condensum'' <small>Millán</small>
|''Allium ascalonicum'' var. ''fertile'' <small>Millán</small>
|''Allium ascalonicum'' f. ''rotterianum'' <small>Voss ex J.Becker</small>
|''Allium ascalonicum'' var. ''sterile'' <small>Millán</small>
|''Allium cepa'' var. ''aggregatum'' <small>G.Don</small>
|''Allium cepa'' var. ''anglicum'' <small>Alef.</small>
|''Allium cepa'' var. ''argenteum'' <small>Alef.</small>
|''Allium cepa'' var. ''bifolium'' <small>Alef.</small>
|''Allium cepa'' var. ''crinides'' <small>Alef.</small>
|''Allium cepa'' var. ''flandricum'' <small>Alef.</small>
|''Allium cepa'' var. ''globosum'' <small>Alef.</small>
|''Allium cepa'' var. ''hispanicum'' <small>Alef.</small>
|''Allium cepa'' var. ''jamesii'' <small>Alef.</small>
|''Allium cepa'' var. ''lisboanum'' <small>Alef.</small>
|''Allium cepa'' var. ''luteum'' <small>Alef.</small>
|''Allium cepa'' var. ''multiplicans'' <small>L.H.Bailey</small>
|''Allium cepa'' var. ''portanum'' <small>Alef.</small>
|''Allium cepa'' var. ''praecox'' <small>Alef.</small>
|''Allium cepa'' var. ''rosum'' <small>Alef.</small>
|''Allium cepa'' var. ''sanguineum'' <small>Alef</small>.
|''Allium cepa'' var. ''solaninum'' <small>Alef.</small>
|''Allium cepa'' var. ''tripolitanum'' <small>Alef.</small>
|''Allium cepa'' var. ''viviparum'' <small>(Metzg.) Alef.</small>
|''Allium cepaeum'' <small>St.-Lag.</small>
|''Allium commune'' <small>Noronha</small>
|''Allium cumaria'' <small>Buch.-Ham. ex Wall.</small>
|''Allium esculentum'' <small>Salisb.</small>
|''Allium napus'' <small>Pall. ex Kunth</small>
|''Allium nigritanum'' <small>A.Chev.</small>
|''Allium pauciflorum'' <small>Willd. ex Ledeb.</small>
|''Allium salota'' <small>Dostál</small>
|''Ascalonicum sativum'' <small>P.Renault</small>
|''Cepa alba'' <small>P.Renault</small>
|''Cepa esculenta'' <small>Gray</small>
|''Cepa pallens'' <small>P.Renault</small>
|''Cepa rubra'' <small>P.Renault</small>
|''Cepa vulgaris'' <small>Garsault</small>
|''Kepa esculenta'' <small>Raf.</small>
|''Porrum cepa'' <small>(L.) Rchb.</small>
}}
|synonyms_ref=<ref>{{ThePlantList |id=kew-295261 |taxon=Allium cepa |authority=L.}}</ref>
}}
An '''onion''' ('''''Allium cepa''''' {{L.}}, from [[Latin]] {{wikt-lang|la|cepa}}), also known as the '''bulb onion''' or '''common onion''', is a vegetable that is the most widely cultivated species of the genus ''[[Allium]]''. The [[shallot]] is a [[variety (botany)|botanical variety]] of the onion which was classified as a separate species until 2011. The onion's close relatives include [[garlic]], [[scallion]], [[leek]], and [[chives]].

The genus contains several other species variously called onions and cultivated for food, such as the Japanese bunching onion ''[[Allium fistulosum]]'', the [[tree onion]] ''Allium''&nbsp;× ''proliferum'', and the Canada onion ''[[Allium canadense]]''. The name ''[[wild onion (disambiguation)|wild onion]]'' is applied to a number of ''Allium'' species, but ''A. cepa'' is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions. The onion is most frequently a [[biennial plant|biennial]] or a [[perennial plant]], but is usually treated as an [[Annual plant|annual]] and harvested in its first growing season.

The onion plant has a fan of hollow, bluish-green leaves, and its bulb at the base of the plant begins to swell when a certain day-length is reached. The bulbs are composed of shortened, compressed, underground stems surrounded by fleshy modified scale (leaves) that envelop a central bud at the tip of the stem. In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become more dry, and brittle. The crop is harvested and dried and the onions are ready for use or storage. The crop is prone to attack by a number of pests and diseases, particularly the [[Delia antiqua|onion fly]], the [[Ditylenchus dipsaci|onion eelworm]], and various fungi which can cause rotting. Some varieties of ''A. cepa'', such as [[shallot]]s and [[potato onion]]s, produce multiple bulbs.

Onions are cultivated and used around the world. As a food item, they are often served raw as a [[vegetable]] or part of a prepared savoury dish, but can be eaten cooked or used to make [[Pickled onion|pickles]] or [[chutney]]s. They are [[wikt:pungent|pungent]] when chopped and contain certain chemical substances which may irritate the eyes.