Apios Americana, sometimes called the potato bean, hopniss, Indian potato or groundnut (but not to be confused with other plants sometimes known by the name groundnut) is a perennial vine native to eastern North America, and bears edible beans and large edible tubers. It grows to 3-4 m long, with pinnate leaves 8-15 cm long with 5-7 leaflets. The flowers are red-brown to purple, produced in dense racemes. The fruit is a legume (pod) 6-12 cm long.
The tubers are crunchy and nutritious, with a high content of starch and especially protein. The plant was one of the most important food plants of pre-European North America, and is now being developed for domestication.
There is a very comprehensive list of corms and tubers here