Onion
Onions are plants in the genus, Allium. They are eaten as vegetables. Most species of onions have bulbs that people can eat. They have a strong flavour and a very distinctive smell.
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| Species: | A. cepa
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| Allium cepa | |
Onions have been grown for a long time. They were probably first grown in Ancient Egypt, together with leek and garlic, but maybe earlier. Now, most of the world's cultures eat onions.
Cultivation
Farmers and gardeners can grow onions from seeds or from bulbs. If they plant seeds, they must later pull out most of the young plants so the rest can grow better. This is called 'thinning'. A different way to plant onions is to plant young bulbs. This is faster, but the onions that grow this way are weaker than the onions that started as seeds.
In food
Onions can be eaten in different ways:
- Fried sliced or chopped onions are often served on hot dogs.
- Onion rings are sliced, the slices dipped in batter, and deep-fried so the batter is crisp and onion is cooked soft.
- Pickled onions are eaten as a relish with chips or with salad.
- Raw onions:
- Sliced (cut into flat layers) for hamburgers and sandwiches
- Chopped or minced fine in salads or as garnish on cooked foods
- Cooked in soups, stews and curries
- Roasted whole alongside roasted meat
Why onions make eyes water
When cutting an onion, the cells of the onion start to open. Then, some chemicals react. When one chemical floats through the air and reaches your eyes, they sting. There are ways to keep the chemical away. You can:
- Cut the onion under water
- Keep the onion in the fridge, and cut when it is cold
- Leave the root end on until last
- Use a sharper knife
- Have a fan blowing away from you on the onion
- Wear goggles, like for swimming or skiing
The ability of plants to deter or limit being eaten is called defence against herbivory.
Gallery
Two colours of onion
Yellow Onions
Flower head of a yellow onion
Onion Media
Roots, leaves and developing bulb
Inflorescence with flower buds
Indian Onion
Medieval woodcut print depicting an onion, from the Latin encyclopedia Hortus Sanitatis (1547)
Frying chopped onions in a frying pan.
Tranby House*jar of pickled onions.
Onion epidermis cells are well known to be visible in true color with only minimal magnification, such as this red onion skin.
Cut onions emit certain compounds which cause the lacrimal glands in the eyes to become irritated, releasing tears.
Onion bulbs used for planting and seeds
Large-scale onion cultivation
Onion grading at the Centre for Agroecology, Water and Resilience, England, using a manually-operated sorter
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