| Peanuts are annual herbaceous plants in the Legume family that are native to South America. They are grown for their edible seed pods, which are also called peanuts. Peanuts are unique in that they grow underground. Above ground, the plants have opposite, pinnate leaves, and small, yellowish orange flowers with red veins. After being pollinated, the flower's ovary elongates and forms a "peg" that grows down into the soil and develops into the peanut. There are two types of peanuts: runner and bunch. Runner peanuts have a vining growth habit and require slightly more space than Bunch peanuts, which do not spread out. Once plants are 30 cm tall, begin hilling soil around them to ensure the pegs and developing peanuts are underground. Peanuts are a tropical plant: they need a long, warm growing season of 90-130 days and can withstand only very light spring and fall frosts. Plants are ready to harvest when the leaves turn yellow and the peanuts' inner shells have gold-marked veins (check by pulling a few nuts out and shelling them). Peanuts should be harvested before the pegs become too brittle, because then the pods will break off in the ground. Peanuts also make a good cover crop because, like other legumes, they fix nitrogen.