Botanically, peanuts are legumes, a large family of plants with the unique ability to grab nitrogen from the air and infuse the soil with it. Legumes include lentils, beans, alfalfa and peas. There is some truth to this story. Peanuts actually are native to South America. Some authorities trace the peanut to Brazil, but older evidence points to Peru, where traces of peanuts have been found in mummy tombs.
Peanuts are tubers or nodules that grow off the roots of the peanut plant.
This misconception comes from the fact that peanuts grow underground, which is the only connection they have with roots. As a peanut plant matures, its stalks bend toward the ground, where its flower deposits its fruit beneath the surface. There it can ripen in safety, protected from insects and animal predators. This evolutionary adaptation is what may have prompted George Washington Carver to recommend the peanut as a replacement for the Southern cotton crop that was destroyed by boll weevils in the 1890s. The culinary use for peanuts is basically peanut butter sandwiches and peanut butter cookies.