- Also called:
- groundnut, earthnut, or goober
- Key People:
- Billy Carter
- George Washington Carver
- Related Topics:
- peanut butter
- Legume
- geocarpy
- nut
- peanut oil
Peanut
- Kingdom: Plantae
- Division: Angiosperm
- Order: Fabales
- Family: Fabaceae
- Genus: Arachis
News •
-
What is a peanut?
The peanut (Arachis hypogaea) is a legume in the pea family (Fabaceae) that is grown for its edible seeds. It is native to tropical South America and was introduced to the Old World tropics early on. The peanut is not a true nut, despite its common names. As with other legumes, the plant enriches soil via nitrogen-fixing bacteria, making it a valuable soil-enriching crop.
Peanuts can be erect shrubby plants or have a spreading form. After pollination, a stalklike structure called a peg carries the fertilized ovules downward into the soil, where the pod develops. Peanut growing needs at least five months of warm weather with rainfall of 60 cm (24 inches) or more during the growing season. The seeds are sold boiled or roasted and are commonly used to produce an edible oil, peanut butter, and in candy and bakery products.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Is a peanut a nut or a legume?
The peanut is a legume of the pea family (Fabaceae), grown for its edible seeds, and not a true nut. As with other legumes, the plant adds nitrogen to the soil by means of nitrogen-fixing bacteria and is thus particularly valuable as a soil-enriching crop. The peanut is an annual and can either be an erect shrubby plant or have a spreading form. Peanut legumes have the peculiar habit of ripening underground, a phenomenon known as geocarpy.
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does a peanut plant grow?
The peanut (Arachis hypogaea) is a legume in the pea family cultivated for its seeds, which are high in protein and fat. It is an annual that can grow as an erect, shrubby plant, or have a spreading form. Its stems bear compound leaves, and it features golden-yellow flowers. After pollination, a stalk-like structure known as a peg grows from the flower base towards the soil, carrying fertilized ovules. The peg's tip develops into the characteristic pod underground, a phenomenon called geocarpy. Peanut plants need at least five months of warm weather with rainfall of 60 cm or more during the growing season.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Where do you find the peanuts on the plant?
The peanut, or Arachis hypogaea, is a legume that has a peculiar manner of ripening its fruit underground, a phenomenon known as geocarpy.
After pollination and withering of the peanut flower, a stalklike structure known as a peg emerges from the flower's base and grows toward the soil. The fertilized ovules are carried downward into the soil by the peg, where the tip then develops into the peanut pod, usually 25–50 mm (1–2 inches) long, containing two or three seeds.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are the main uses of peanuts?
The peanut, while referred to as a nut, is a legume prized for its nutritious seeds. These seeds are rich in both protein and fat, making them a valuable food source.
Peanuts are sold boiled or roasted. They are also processed into peanut oil, used as salad oil, and in the manufacturing of margarine and soap. Additionally, peanuts are ground into peanut butter, a popular spread and ingredient in candies and baked goods.
Beyond human consumption, peanuts serve as a high-protein animal feed, with the tops of the plants used as hay for livestock. George Washington Carver's research led to around 300 diverse applications, including flour, soaps, and plastics.
4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do peanuts help improve soil quality?
Peanuts, like other legumes, have a symbiotic relationship with nitrogen-fixing bacteria in the soil. These bacteria convert free nitrogen into ammonia, which the peanut plant uses for its development. As a result, peanuts add nitrogen to the soil, enriching it and making it valuable as a soil-improving crop.
Crop rotation with legumes such as peanuts can maintain soil productivity, improve soil structure, and reduce erosion. While some legumes deposit nitrogen as protein in the harvested seed, turning under the top growth of a legume aids in adding nitrogen to the soil.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Peanut, (Arachis hypogaea), tropical South American legume plant widely cultivated for its edible seeds. The seeds, which are also known as peanuts, are a nutritionally dense food, rich in protein and fat. Despite its several common names, the peanut is not a true nut. As with other legumes, the plant adds nitrogen to the soil by means of nitrogen-fixing bacteria and is thus particularly valuable as a soil-enriching crop.
Physical description and geocarpy
The peanut is an annual and can either be an erect shrubby plant, 45–60 cm (18–24 inches) high with short branches, or have a spreading form, 30–45 cm (12–18 inches) high with long branches that lie close to the soil. The stems are sturdy and hairy and bear pinnately compound leaves with two pairs of leaflets. The flowers are borne in the axils of the leaves and feature golden-yellow petals about 10 mm (0.4 inch) across. The oblong pods have rounded ends and are most commonly 25–50 mm (1–2 inches) long with two or three seeds; the pods are contracted between the seeds and have a thin, netted, spongy shell. The seeds vary from oblong to nearly round and have a papery seed coat that ranges in color from whitish to dark purple.
Peanut legumes have the peculiar habit of ripening underground, a phenomenon known as geocarpy. After pollination and the withering of the flower, an unusual stalklike structure called a peg grows from the base of the flower toward the soil. The fertilized ovules are carried downward in the sturdy tip of the peg until the tip is well below the soil surface, at which point the peg tip starts to develop into the characteristic pod. The pegs sometimes reach down 10 cm (4 inches) or more before their tips can develop fruits. These unusual fruits appear to function as roots to some degree, absorbing mineral nutrients directly from the soil. The pods may not develop properly unless the soil around them is well supplied with available calcium, regardless of the nutrients available to the roots.
" height="20" alt="HEW Logo">
Cultivation
Peanut growing requires at least five months of warm weather with rainfall (or irrigation equivalent) of 60 cm (24 inches) or more during the growing season. The best soils are well-drained sandy loams underlain by deep friable (easily crumbled) loam subsoils. At harvest the entire plant, except the deeper roots, is removed from the soil. The pods are often cured by allowing the harvested plants to wilt for a day, then placing them for four to six weeks in stacks built around a sturdy stake driven upright into the soil. The pods are placed toward the inside of each stack to protect them from weather.
Uses
Peanuts are sold boiled or roasted and are commonly used to produce an edible oil with a high smoke point. In the United States the seeds are also ground into peanut butter and widely used in candy and bakery products. The peanut is used extensively as feed for livestock in some places; the tops of the plants, after the pods are removed, usually are fed as hay, although the entire plant may be so used. The development of some 300 derivative products from peanuts—including flour, soaps, and plastics—stems mainly from research conducted in the early 20th century by George Washington Carver.