Commonly called the rex begonia vine. It isn't a begonia at all but it is more in the grape family. Its name is cissus discolor.

Mine defoliates each winter, but has come back each spring. It is still in its original pot after 3 years. This year it has grown considerably more by putting the pot on the ground instead of hanging it up.

I think the most beautiful one I've seen was in a greenhouse where it was very loosely trained to go up a post. Seemed to like growing up a lot. Really a beautiful species.