Peanut

Peanut, common name for an annual warm-season plant of the legume family, and for its seeds. Peanuts originated in South America, probably in Brazil, and have been cultivated since ancient times by Native Americans. Plants grow about 75 cm (about 30 in) tall and can spread 1.2 m (4 ft). Some types develop a bunchy erect growth; others, called runners, spread over the ground. The peanut is unusual in that, after the flower is fertilized, the elongated receptacle, called the peg, turns downward from the base of the flower stalk to bury the ovary tip in the soil, where the fruit or pod develops.

Many types of peanuts exist, and both large- and small-seeded kinds are grown extensively in the United States. Large-seeded varieties are used for roasting and confections, and small-seeded types are used for peanut butter and oil. After peanuts are harvested, the plants are used as forage for livestock. The traditional use as fodder and grain feeds for cattle and hogs has declined.

Peanuts require sunshine, a warm growing season of 120 to 140 days, and moderate rainfall. They do best on well-drained sandy soils; dark soils tend to stain the shells. Traditionally, production has been in the southern United States and in the warm-season areas of South America, Africa, and Asia.

Peanuts are nutritious and high in energy. The seeds contain 40 to 50 percent oil and 20 to 30 percent protein, and they are an excellent source of B vitamins. About half the peanuts grown in the United States are made into peanut butter, and one-fourth are sold as roasted peanuts. Peanut oil is also popular as a high-quality salad and cooking oil and is commonly used in margarine.

The leading peanut-producing countries, in order of production, are China, India, and the United States. In the United States peanuts are grown primarily for food; in other countries they are used principally for edible oil. Production in the United States averages 1.9 million metric tons annually, about one-tenth of the world crop, with nearly half the United States crop grown in Georgia.

Scientific classification: The peanut belongs to the subfamily Papilionoideae, family Fabaceae (formerly Leguminosae). It is classified as Arachis hypogaea.