Arachis hypogaea

Arachis hypogaea, or peanut, is a legume that is native to Central Brazil and now widely grown worldwide, mainly for its edible seeds. The species name hypogaea means "under the earth" and reflects that fact that the pods containing edible seeds grow below ground. The peanut is an herbaceous perennial, but grown as an annual. It produces flowers above ground, but develops the fruit below ground in a process known as geocarpy. Like most legume plants, peanuts have roots which contain nodules of nitrogen fixing bacteria making it a valuable soil-enriching crop. When removing plant remains at the end of the growing season, only remove the aerial parts of the plant and leave the roots in the ground to decay and release their nitrogen.

Peanut plants thrive in warm climates with full sun and well-drained, light, sandy, loam soil. Plants are not frost-hardy and are best grown in areas with long warm summers. Plant seeds in the spring after the ground has warmed, in well-composted, fertile, light-textured, sandy, well-drained soils in full sun. Plant seeds (peanuts) about 2” deep in rows about 3 feet apart with 6-9” between each plant in the row. After first fall frost, dig up the plants, shake off the soil, and spread on a dry surface not touching the ground to cure before stripping the pods from the plants. Pods typically ripen 120-150 days after seed is planted.

Most varieties can either be in erect form or a runner form with a growth cycle of 4-5 months depending on the variety. The attractive, low-growing ,yellow pea-like flowers pollinate themselves then produce a ‘peg’ that grows down and away from the plant into the soil from which the peanut seed pod will develop.

Four main types of peanut varieties are grown in the United States:

• A Runner peanut, the most commonly grown peanut plant, is often used in the production of peanut butter.
• Virginia style peanuts have the largest kernels and are often processed in-the-shell and used as gourmet peanuts. North Carolina is a major producer of Virginia peanuts.
• Spanish peanuts have smaller kernels covered with a reddish brown skin and are often used in peanut confections. They are higher in oil content than other varieties.
• Valencia peanuts have 3 or more seeds per pod and are covered in a bright red skin. They are very sweet peanuts and are popular roasted or boiled.

Diseases, Pests, and Other Plant Problems:

Disease suseptibility includes leaf spots, southern stem rot, Sclerotinia blight, Cylindrocladium black rot and Spotted wilt. The plant is allelopathic, meaning it suppresses the growth of other plant species by releasing toxic substances. The seeds of peanuts contain proteins that have allergen properties which may result in serious allergic reactions in some people.