The wild carrot is native to Afghanistan and Iran. China now grows about half of the world's carrots. They are used cooked and raw in salads. They are also put into cakes.

Carrots were first grown for their leaves and seeds rather than their roots. Their relatives - parsley, fennel, dill and cumin - are still used that way.

The root was first used about 2000 years ago, and introduced to Europe in the 8th century.

These first carrots had purple roots. Orange-coloured carrots were cultivated in the Netherlands in the 17th century. European settlers introduced the carrot to Colonial America in the 17th century.

Most carrots are about 7% sugar, 1% protein and 1% fibre. They have no starch. The bright orange colour comes from tiny amounts of a substance called beta-carotene. When eaten, this turns into vitamin A. Lack of vitamin A can cause poor vision, including night vision, so this is why vitamin A is useful to the diet.

Carrots are also rich in antioxidants and minerals. They can even be used to treat constipation.

Only 3 percent of the beta-carotene in raw carrots is released during digestion, but much more is released if the carrot is cooked. So cooked carrots are better for you than raw ones. Carrots were one of the main ingredients in the pottage of the Middle Ages. Carrots were also used in Britain during World War II, when it was suggested (incorrectly) that they made it possible to see in the dark. But it was a good ruse to get people to eat carrots, which were plentiful and cheap. Our World War II section has more.

To grow straight, carrots need hard soils. If the soil is loose, they grow many roots.