Because they grow underground, peanuts are sometimes called groundnuts. Peanuts are used to make cooking oil, peanut butter, animal feed, and many other products. They are an excellent concentrated source of food energy, protein, vitamins, and minerals. Peanuts are not really true nuts. Instead they belong to the group of plants called legumes, which also includes peas, beans, soybeans, and clover.

Where peanuts are grown

Peanuts are grown in warm areas throughout the world. They require a growing season at least five months long. They also need at least 24 inches (61 centimeters) of rainfall during this season. Peanuts grow best in sandy soils. The world's leading peanut-producing countries include China, India, the United States, and Nigeria.

Physical features

The peanut plant is a low bush. Some plants grow short branches and have an upright stem as tall as 24 inches (61 centimeters). Others have a shorter stem but grow long branches called runners that lie close to the soil. The stems and branches of both types of plants are sturdy and hairy. The leaves are made up of two pairs of green, oval parts called leaflets. Small yellow flowers grow on the lower part of the plant. They emerge in the crook between the leaves and the stem.

After a peanut flower receives pollen from another flower, it begins to wither. A stalklike stem called a peg then juts down from the bottom of the flower and gradually pushes back into the soil. Each plant has many such pegs. The tip of each peg develops into a pod beneath the soil. A peg may reach down 4 inches (10 centimeters) or more before its tip develops a pod. The pod absorbs nutrients from the soil.

The pods of the peanut plant are what most people recognize as the thin, spongy shell of the peanut. The pods are rounded and oblong. Pods typically measure about 1 to 2 inches (2.5 to 5 centimeters) long. Each holds two to four seeds. The seeds have a papery seed coat that is commonly called the skin. Most seed coats are reddish, but others are purple or white.

Processing

To harvest peanuts, the main root of the plant is cut. The rest of the plant is then lifted out of the soil. The plant and pods are left to dry in the sun before the pods are removed. The pods are dried further and cleaned before they are sent to a factory for processing. The plants are turned into the soil or baled like hay for animal feed.

Uses

In the United States huge quantities of peanuts are ground into peanut butter. In other places most of the peanut crop is crushed for oil, which is used in cooking and salad dressing. Peanuts that are not ground up are used in cooking, baking, and candy making. People also eat roasted peanuts as a snack. Peanuts and peanut plants are sometimes fed to animals. Peanuts are also used in a wide variety of other products, including flour, soaps, and plastics.

History

The peanut is native to tropical South America. Hundreds of years ago peanuts were taken to Asia, Africa, and North America. Early in the 20th century the U.S. scientist George Washington Carver developed hundreds of new products from peanuts.