My vote is with Greene...
Apios americana.
I'd wait for a bloom and post at the plant id forum
http://garden.org/forums/view/...
If you are lucky enough to have ground nut.... You might want to keep it...
There have been a LOT of people posting on seed forums begging for apios...
I recently found some again... and am still trying to out-wit the voles enough to get a stand going.
