Onion
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What is an onion plant?
The onion (Allium cepa) is a herbaceous biennial plant. Likely native to southwestern Asia, it is now cultivated worldwide, especially in temperate zones.
Onion plants have one or more leafless flower stalks that can reach up to 1.8 meters, with a spherical cluster of small greenish-white flowers at the top. Some clusters produce tiny secondary bulbs called bulbils, which can propagate new plants asexually. The plant's concentric leaf bases swell to form the edible bulb underground.
Onions are typically grown from small black seeds sown directly in the field, but they can also be grown from small bulbs or transplants. They are hardy and adaptable to various growing conditions. Bulb size, shape, color, and pungency differ, with warmer climates generally yielding milder, sweeter onions. Onions are valued for their flavor, adding taste to stews, roasts, soups, and salads, and can also be served as a cooked vegetable.
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What does an onion plant look like?
An onion plant features one or more leafless flower stalks that can grow to be 2.5 to 6 feet tall. At the top of these stalks, you'll find a spherical cluster of small, greenish-white flowers. Some of these flower clusters produce tiny secondary bulbs called bulbils, which can grow new plants.
The plant also develops an underground bulb, which is the edible part we commonly know as an onion. These bulbs come in various sizes, shapes, colors, and levels of pungency. Onions can be grown from seeds, small bulbs, or transplants and are known for being hardy, able to survive in diverse conditions.
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How do onions grow underground?
The concentric leaf bases of the developing onion plant swell to form the edible bulb underground. Onions are typically grown from seeds sown directly in the field, but can also be grown from small bulbs or transplants. As the scales of underground bulbs mature, buds may form at their base and become bulblets. As the parent scales fall apart, these bulblets grow into new individuals. The tree onion, or Egyptian onion, which is a hybrid of Allium cepa, produces bulblets instead of flowers on top of the flowering stalk.
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What are the main parts of an onion plant?
The main parts of a common onion plant include:
* Flower stalks One or more leafless flower stalks that can reach 75ā180 cm tall, ending in a cluster of small, greenish-white flowers.
* Bulbils Some flower clusters produce tiny secondary bulbs that can propagate new plants asexually.
* Bulb The concentric leaf bases of the developing plant swell and form the edible bulb underground. Onions are bulb vegetables of the genus Allium.
* Roots The basal plate of the bulb may grow roots.2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How are onions used in cooking and eating?
Onions are grown worldwide and are valued for their flavor in cooking. They enhance dishes like stews, roasts, soups, and salads, and can be served as a cooked vegetable.
They are available in many processed forms, such as boiled and pickled, frozen (chopped or whole), and as bottled juice for flavoring. Dehydrated forms include granulated, ground, minced, chopped, and sliced. Onion powder is often combined with salt and used in prepared foods or sold as a condiment.
There are also many commercial varieties, such as globe-shaped onions, Bermuda onions, Spanish onions, Italian onions, shallots, pearl onions, spring onions, and green onions, which all have different culinary uses.
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Why do onions make people cry when they are cut?
When you cut an onion, you break open cells, which releases enzymes that mix with sulfur-rich amino acids. This process forms syn-propanethial-S-oxide, a volatile chemical that vaporizes and causes a burning sensation when it reaches your eyes. To protect your eyes, your brain triggers a tear response to rinse away the irritant, resulting in tears.
To reduce tearing, use less sulfurous onion varieties or chill onions before cutting to slow down the responsible enzymes. Some people try tricks like lighting a match or eating bread, but these are less effective.
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Onion, (Allium cepa), herbaceous biennial plant in the amaryllis family (Amaryllidaceae) grown for its edible bulb. The onion is likely native to southwestern Asia but is now grown throughout the world, chiefly in the temperate zones. Onions are low in nutrients but are valued for their flavour and are used widely in cooking. They add flavour to such dishes as stews, roasts, soups, and salads and are also served as a cooked vegetable.
Physical description
The common onion has one or more leafless flower stalks that reach a height of 75ā180 cm (2.5ā6 feet), terminating in a spherical cluster of small greenish white flowers. Some flower clusters produce bulbils, tiny secondary bulbs that can be used to asexually propagate new plants. The concentric leaf bases of the developing plant swell to form the underground edible bulb. Most commercially cultivated onions are grown from the plantās small black seeds, which are sown directly in the field, but onions may also be grown from small bulbs or from transplants. Onions are very hardy and can survive in a wide range of growing conditions. The bulbs vary in size, shape, colour, and pungency, though warmer climates generally produce onions with a milder, sweeter flavour than do other climates. The onionās characteristic pungency results from the sulfur-rich volatile oil it contains; the release of this oil during peeling or chopping brings tears to the eyes.
History
Onions are among the worldās oldest cultivated plants. They were probably known in India, China, and the Middle East before recorded history. Ancient Egyptians regarded the spherical bulb as a symbol of the universe, and the concentric spheres of the Aristotelian cosmos were also likened to an onion. Its name is probably derived from the Latin unus, meaning āone.ā The Romans introduced the onion to Britain and, in the New World, Native Americans added a highly pungent wild onion (Allium canadense) to their stews. Curative powers have been attributed to onions throughout the centuries; they have been used in folk medicine for such varied ailments as colds, earaches, laryngitis, animal bites, burns, and warts.
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Onion products, varieties, and cultivars
Most whole onions are slightly dried before marketing, making their skins dry and paper-thin. Onions are also available in various processed forms. Boiled and pickled onions are packed in cans or jars. Frozen onions are available chopped or whole, and bottled onion juice is sold for use as a flavouring. Dehydrated onion products have been available since the 1930s; such products include granulated, ground, minced, chopped, and sliced forms. Onion powder is made by grinding dehydrated onions and is sometimes packaged in combination with salt. Dried onion products are used in a variety of prepared foods and are also sold directly to the consumer for use as condiments.
There are a number of commercial varieties and cultivars of onions available:
- Globe-shaped onions may be white, yellow, or red. They have strong flavour and are used chiefly for soups, stews, and other prepared dishes and for frying.
- Bermuda onions are large and flat, with white or yellow colour and fairly mild taste. They are often cooked and may be stuffed, roasted, or french-fried. They are also sliced and used raw in salads and sandwiches.
- Spanish onions are large, sweet, and juicy, with colour ranging from yellow to red. Their flavour is mild, and they are used raw and sliced for salads and sandwiches and as a garnish.
- Italian onions, or cipollini onions, are flat and are red, white, or yellow in colour and often have a mild, sweet flavour. They are used raw for salads and sandwiches, and their outer rings make an attractive garnish.
- Shallots are a small, angular variety of onion. They are typically white with a brown or red skin and have a mild flavour. The green leaves can also be eaten.
- Pearl onions are not a specific variety but are small round onions harvested when 25 mm (1 inch) or less in diameter. They are usually white and pickled and used as a garnish and in cocktails.
- Spring onions are small white onions that are picked when between 25 and 38 mm (1 and 1.5 inches) in diameter; the tops are sometimes left attached. They are used to flavour foods having fairly delicate taste, such as omelets and other egg dishes, sauces, and peas. They are also served boiled or baked.
- Green onions, also called scallions, are young onions harvested when their tops are green and the underdeveloped bulbs are 13 mm (0.5 inch) or less in diameter. Their flavour is mild, and almost the entire onion, including top, stem, and bulb, is used raw in salads and sauces, as a garnish, and as a seasoning for prepared dishes.