Groundnut, peanut or monkey nut
Family Leguminosae: Papilionaceae (or Fabaceae)
Arachis hypogaea, the groundnut, peanut or monkey nut (A. hypogaea 1), is an annual herb, 15-60 cm tall, erect or trailing, with spirally arranged compound leaves with 4 leaflets, and yellow flowers, borne in the leaf axils (A. hypogaea 2).
Each flower with 5 sepals with 4 fused into a superior lip, 5 petals, and 10 stamens of which the filaments are fused for about half their length, with 2 sterile; and ovary with long style and club-shaped stigma. After fertilisation, a fruit appears at the end of a structure known as the peg. This peg elongates and grows downwards into the soil to a depth of about 5-7 cm, and then it turns to a horizontal position. The mature fruit has a reticulate outer skin and contains 1-6 seeds with a paper-thin reddish seed coat (A. hypogaea 3). Fruits and seeds vary in size, shape and colour of the seed coat. The seeds contain up to 50% oil, mainly oleic acid and linoleic acid, and are rich in vitamins B and E.
Distribution
The groundnut is of South American origin. Columbus recorded extensive cultivation of it in Central America and the West Indies. In the 16th century the Portuguese took the groundnut from Brazil to West Africa, and the Spanish took it further to the Philippines. Today the plant is distributed widely in all tropical and subtropical countries.
Use
In India and Nigeria the pounded groundnut is an important source of proteins (A. hypogaea 4). In the temperate regions roasted peanuts are eaten as dessert nuts and in sweets and confectionery. In the US most of the crop is used for peanut butter. Groundnut oil is used as salad and cooking oil, for the manufacture of margarine and soap, and as a lubricant. The press cake is fed to livestock.
Biggest producers are India, China and Nigeria. Other important exporting countries are Senegal (A. hypogaea 5), Sudan, Gambia, Niger and Brazil and Argentina in the New World. Most of the exported groundnuts are taken to Europe; the production of the US is consumed internally. The yields vary from 400-1300 kg of nuts per ha annually. Only in the US harvesting is done by machines, everywhere else in the world by hand.