The peanut, or Groundnut (Arachis hypogaea), is a species in the legume family Fabaceae native to South America, Mexico and Central America. 1 It is an annual herbaceous plant growing to 30 to 50 cm (1 to 1½ ft) tall. The leaves are opposite, pinnate with four leaflets (two opposite pairs; no terminal leaflet), each leaflet 1 to 7 cm (⅜ to 2¾ in) long and 1 to 3 cm (⅜ to 1 inch) broad. The flowers are a typical peaflower in shape, 2 to 4 cm (¾ to 1½ in) across, yellow with reddish veining. After pollination, the fruit develops into a legume 3 to 7 cm (1 to 2 in) long containing 1 to 4 seeds, which forces its way underground to mature.

The plant's name derives from a combination of the morphemes pea and nut, causing some confusion as to the nature of the fruit. Although a nut in the culinary sense, in the botanical sense the fruit of the peanut plant is a woody, indehiscent legume and not a nut. The word pea describes the edible seeds of many other legumes in the Fabaceae family, and in that sense, a peanut is a kind of pea.

Peanuts are also known as earthnuts, goobers, goober peas, pindas, jack nuts, pinders, manila nuts, and monkey nuts. (The last of these is often used to mean the entire pod)

History

Evidence demonstrates that peanuts were domesticated in prehistoric times in Peru. Archeologists have thus far dated the oldest specimens to about 7,600 years before the present. Cultivation spread as far as Mesoamerica where the Spanish conquistadors found the tlalcacahuatl (Nahuatl = "cacao", whence Mexican Spanish, cacahuate and French, cacahuète) being offered for sale in the marketplace of Tenochtitlan (Mexico City). The plant was later spread worldwide by European traders. Cultivation in the English colonies of North America was popularized by African Americans, who brought the Kikongo word "nguba", which in the United States became "goober".

The nut gained Western popularity when it came to the United States from Africa. It had become popular in Africa after being brought there from Brazil by the Portuguese around 1800.

Cultivation

The flower of the Arachis hypogaea is borne above ground and after it withers, the stalk elongates, bends down, and forces the ovary underground. When the seed is mature, the seed coat (mesocarp) changes color from white to a reddish brown. The entire plant, including most of the roots, is removed from the soil during harvesting.