Know your Onions

Onion is a term used for many plants in the genus Allium.

They are known by the common name "onion" but, used without qualifiers, it usually refers to Allium cepa.

Allium cepa is also known as the "garden onion" or "bulb" onion.

It is grown underground by the plant as a vertical shoot that is used for food storage, leading to the possibility of confusion with a tuber, which it is not.

Allium cepa is known only in cultivation, but related wild species occur in Central Asia.

The most closely related species include Allium vavilovii (Popov & Vved.) and Allium asarense (R.M. Fritsch & Matin) from Iran. However, Zohary and Hopf warn that "there are doubts whether the vavilovii collections tested represent genuine wild material or only feral derivatives of the crop."