I made an unbeliveable score yesterday at Tonkadale Nursery in Minnetonka , MN.
The leaves are up to 8 inches in diameter and almost perfectly round/flat not very wavy at all (looks to me if I grew new leaves in my terrraums they may have almost no wave due to better humidity and light).The flower stalks are over 2 feet in height. The rhizome creeping on the surface is almost 2" in diameter. I paid a whopping $3.99 for it (it was grown in (and out) of a 4" pot! The catch is they couldn't tell me what kind it was or if a hybrid, what that was since I had dug it off their older stock shelves it had clearly been there for quite some time. I haven't fund any pictures in my books or online (including the begonia society webpages) of anything like it. The closest I can find is the Rhizomatous Begonia hydrocotylifolia except it's leaves only get to several inches and these are huge. The other possibilty could be B. nelumbifolia but the flowers are not similar.
Also, apparently my plant shown above has all female flowers and no males flowers on it at all. That's how the other 2 of this plant at the greenhouse were too, huge and all female in 4" pots...
If anyone has an idea what this is I'm all ears! I want to be sure and make it an even more impressive specimen!