Onions are a species in the genus Allium that are native to Central Asia. They have upright green leaves attached to a swollen bulb underground. Common varieties include red, white and yellow onions. Different varieties bulb at different daylight hours, with long day bulbs requiring more light. Onions are available seasonally from spring through winter.

2. Kingdom: Plantae Division: Magnoliophyta Class: Liliopsida Order: Asparagales Family: Alliaceae Genus: Allium Species: A. cepa

3. Botanical name: Allium cepa Family : Liliacea Origin & distribution : Central Asia ( Iran &Pakistan)

4. Onions have upright, cylindrical, green leaves attached to the swollen leaf bases that form the bulb below ground. Onion plants grow to be about two feet high Green onions, also called scallions, are either onions that are harvested when they are young or a special type of onion called bunching onion that has small bulbs.

5. Onion are mainly available in red, white and yellow varieties. Some of the onion varieties are Ailsa Craig, Red Baron, Centurion, Orion, Lisbon, Express Yellow .

7. "Long Day Bulbs" begin to form a bulb, when there is 14-16 hours of daylight. They include Sweet Spanish Onions and Walla Walla onions. "Short Day Bulbs" will begin to bulb when there is 12 - 14 hours of daylight hours. Short day bulbs include Yellow Granex, Texas Grano and Red Burgundy.

8. March – August : Spring/summer fresh onions are available in this season and they are identified by light, thin skin coloured . August – April : Fall/winter onions are available and are identified by thick , dark ,papery skin

9. The main purpose of onion is cooking other than that it is used for Treating bronchial pneumonia Curing cough To treat sore throats To treat bee stings To cure earache It also boosts immune system