a twining, leguminous vine (genus Amphicarpaea) native to E North America: the flowers borne near the ground develop bladdery pods underground
See hog peanut in American Heritage Dictionary 4
noun
A twining North American vine (Amphicarpaea bracteata) having clusters of pinkish or white flowers and bearing three-seeded pods as well as basal or underground fleshy one-seeded pods.