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August 1, 2026Short & citedBlog
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Field Notes • Plants

Onion

The onion (*Allium cepa*) is a cultivated plant grown mainly for its edible bulb, which is widely used as a flavouring vegetable.

Updated August 1, 20261 min readCited sources

The onion (Allium cepa) is a cultivated plant grown mainly for its edible bulb, which is widely used as a flavouring vegetable. It is a biennial plant in the amaryllis family that is usually grown as an annual and is cultivated around the world, especially in temperate regions.

Description

The onion is a bulb-forming plant with hollow leaves and a short stem at the base of the bulb. Its edible bulb is made of concentric fleshy leaf bases and is valued for its pungent flavour.

Cultivation and distribution

Onions have been cultivated for thousands of years and are grown globally today. Sources identify southwestern or central Asia and Persia as likely origins, with later spread into many regions and large-scale production in countries such as China, India, and the United States.

Uses

The bulb is the most commonly eaten part, but the stems and leaves are also edible. Onions are used raw, cooked, dried, dehydrated, boiled, or pickled, and they are a major flavouring ingredient in many cuisines.

In short

  • One of the most widely cultivated species in the genus Allium.
  • Grown primarily for its edible bulb.
  • Usually grown as an annual crop despite being naturally biennial.
  • Likely native to southwestern Asia and now grown worldwide.
Canadian angle

Onions are a common cool-season vegetable grown in Canadian gardens and agriculture, and they are widely used in Canadian cooking.

Quick questions

What is the scientific name of the onion?
The scientific name is Allium cepa.
What family does the onion belong to?
It belongs to the amaryllis family, Amaryllidaceae.
Which part of the onion is eaten?
The bulb is the main edible part, though the leaves and stems are also edible.

Sources

  1. Wikipediahttps://www.wikiwand.com/en/articles/Onion
    Supports: Scientific name, genus, and status as a widely cultivated Allium species.
  2. Encyclopaedia Britannicahttps://www.britannica.com/plant/onion-plant
    Supports: Description, family, likely native range, cultivation, and culinary uses.
  3. Penn State PlantVillagehttps://plantvillage.psu.edu/topics/onion/infos
    Supports: Edible bulb, leaves and stems, and common uses.
  4. Britannica Kidshttps://kids.britannica.com/students/article/onion/276190
    Supports: Plant description, edible bulb, origin, and production regions.
  5. New Mexico State Universityhttps://onion.nmsu.edu/resources/facts.html
    Supports: Origin area, cultivation history, and family-related facts.
  6. University of California Agriculture and Natural Resourceshttps://ucanr.edu/sites/default/files/2010-09/52157.pdf
    Supports: Onions as a cool-season biennial plant usually grown as an annual.
  7. University of Connecticuthttps://homegarden.cahnr.uconn.edu/factsheets/onions/
    Supports: Genus relationships, cultivation, and long history of cultivation.
  8. North Carolina State Universityhttps://plants.ces.ncsu.edu/plants/allium-cepa/
    Supports: Family placement, edible bulbs and tops, and origin notes.