I think it's probably a Cyclanthaceae. It might be able to grow in a riparium. I remember seeing some in Costa Rica growing right along the edges of streams. I would try it with the bottom 1/2 of the planter cup filled with Hydroton so that there is free water diffusion around the roots.
Check out these pictures of
Cyclanthus...
http://images.google.com/images?hl=e...-8&sa=N&tab=wi