Onion, common name for herbaceous biennial
plant and its edible bulb of the lily family, native to Asia but
cultivated in temperate and subtropical regions throughout the
world for thousands of years.
The plant belongs to the lily family, most members of which have
an underground storage system, such as a bulb like plants such
as the leek, garlic, chive, shallot and the green onion.
Onions are among the world's oldest cultivated plants. They were
probably known in India, China, and the Middle East before
recorded history. Leading world producers of dry onions include
China, India, the United States, Russia, Japan, Turkey and
Spain.
Onions are among the hardiest of all garden-vegetable plants and
are used widely in cooking. Although they add flavour to such
dishes as stews, roasts, soups, and salads, they are actually
low in nutrients and are also served as a cooked vegetable.
Onions vary in size, shape, colour, and pungency. Warmer
climates produce onions with a milder, sweeter flavour than do
other climates.
The plant contains sulphurous, volatile oils that give it a
characteristic pungent taste; one component readily dissolves in
water to produce sulphuric acid, contact of the vapour to your
eyes is what causes tears as you cut the fresh plant.