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Onion facts for kids

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Quick facts for kids
Scientific classification
Binomial name
Allium cepa

Onions are vegetables. They are plants in the genus Allium. When people talk about onions, they usually mean garden onions. Onions have bulbs, which are edible, in most species. They have a strong flavour, and a very distinctive smell.

Onions have been grown for a very 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.

How onions are grown

Onion Flower Head
Flower head of a yellow onion

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.' Or, they can plant young bulbs. This is faster, but the onions that grow this way are weaker than the onions that started as seeds.

How onions are eaten

Onions can be eaten in different ways. Fried onions are often served with hot dogs. Pickled onions are eaten with chips or with salad. Raw onions are sliced (cut into flat layers) for hamburgers. Chopped onions are put in many stews and curries. Onions are sometimes roasted whole.

Why onions make eyes water

Cortando cebolla
Cut onions emit certain compounds which cause the lacrimal glands in the eyes to become irritated, releasing tears.

When you cut an onion, you open some cells of the onion. 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

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