groundnut

Short definition from Wiktionary

Noun

1. 1
   A climbing vine, Apios americana, of eastern North America, having fragrant brownish flowers and small edible tubers.
2. 2
   Any similar plant having underground tubers.
3. 3
   The nutlike tuber of such a plant, especially peanuts.
4. 4
   A plant which bears its nutlike seeds underground, such as a peanut (Arachis hypogaea) or a Bambara groundnut (Vigna subterranea).