Peanuts are confusing. We think of them as nuts but they grow underground. So, are peanuts roots? Are they seeds like other nuts? Or are they peas, as the name suggests; a nut-like pea. The peanut, native to South America, has been used for food for thousands of years and we are still confused about it. Is it possible for something to be a nut and a pea? Or, can the roots of a plant be like a nut?
Are Peanuts Roots?
Peanuts are not roots. Peanut plants are unusual because they flower above ground but it ‘fruits’ below the ground. In other words, peanuts are the fruits of a peanut plant, and this fruit grows under the ground.
Peanuts start out like most plants. A seedling breaks through the soil and grows until they are about 18 inches tall. After around 40 days, yellow flowers appear on the lower part of the plant. The peanut flowers pollinate themselves and then the flowers fall off. Meanwhile, a peanut ovary starts to form. This is called a ‘peg.’
As the peg grows it extends a stem down toward the ground and then it penetrates the ground. The peanut embryo, or baby peanut, is at the tip of this peg and once it is embedded in the soil, it turns to a horizontal position and begins to mature into a full-grown peanut. After 130 to 140 days a peanut plant will produce around 30 to 40 peanuts.
Are Peanuts Nuts?
The peanut, or Arachis hypogaea is not a nut at all. It is actually a legume or pea and is a close relative of the black-eyed pea. It is also called the groundnut, earthnut, pindar, pignut, pygmy nut, monkey nut, goober, or goober pea.
Peanuts are part of the Fabaceae or Leguminosae family of flowering plants that we normally think of as the legume, pea, or bean family.
Regardless of whether the peanut is a nut, we think of it as a nut in the culinary sense and it is more similar in taste and appearance, as well as nutrition, to actual nuts than it is to peas. Peanuts have around 350% more protein than peas!
Taking all types of peanuts together, a cup of peanuts will contain around 38 grams of protein. One cup of green peas contains only 8 grams of protein and one cup of black-eyed peas contains only 5 grams of protein.
Is The Peanut the Only Legume That Grows Underground?
No, while the peanut is the most widely used and commercially important ‘ground nut,’ it is not hte only one. Another example is the Bambara groundnut or Vigna subterranea, also part of the legume family. It is also called the Bambara nut, the Bambara bean, Congo goober, earth pea, ground-bean, or hog-peanut.
The Bambara groundnut is native to West Africa and is an important food source is in African countries where it is grown. It is grown widely in sub-Saharan Africa and is also found in Thailand, Malaysia, and Indonesia.
While the Bambara nut is associated with subsistence farming, nutritionally, it can be an important food crop worldwide due to its unique features. The paper, Bambara Groundnut: An Underutilized Leguminous Crop for Global Food Security and Nutrition provides a thorough introduction and overview of this valuable food crop:
[The Bambara groundnut] is a hardy crop and has been recognized as an important nutritious food source when food is scarce. This could be attributed to its climate-smart features, including its ability to fix nitrogen, and to grow under adverse environmental conditions such as poor soils and drought. This nutrient-dense legume is sometimes termed a “complete food” due to its balanced macronutrient composition. Bambara groundnut contains ~64.4% carbohydrate, 23.6% protein, 6.5% fat, and 5.5% fiber and is rich in minerals. It is relatively underutilized compared with major cash crops…
