Peanut

The peanut is the seed of Arachis hypogaea, a legume related to beans and peas rather than to tree nuts. The plant is a small annual herb that likely originated in South America and is now cultivated in many warm regions. After flowering, a stalk called a peg, or gynophore, grows downward and pushes the developing fruit into the soil, where the pods mature.

The flowers themselves form above the ground, which makes this underground development unusual. Each pod usually contains one to four seeds covered by a thin reddish skin. The plant is also able to form a partnership with soil bacteria that help convert atmospheric nitrogen into compounds it can use, although this process depends on the plant, the bacteria and the growing conditions.

Farmers harvest the mature pods from the soil and dry them before storage or processing. Nutritionally, peanuts provide plant protein, unsaturated fats, fiber and several vitamins and minerals, including vitamin E, magnesium and niacin. They are therefore rich in energy and can be included, in suitable portions, in a varied diet.

Peanuts may be eaten raw or roasted and are used to make peanut butter and peanut oil. They also appear in sauces, sweets and many dishes. Peanut allergy can be serious, so people who need to avoid peanuts should check food labels carefully.