Your picture is very small, but it looks just like Begonia epipsila, which I grow. I've only seen B. sanguinea in pictures, but there are many similarities:

1. Both are species from Brazil.
2. Both are glabrous.
3. Both are classified as semi-erect, shrub-like, medium-leaved.
4. The leaves of both seem to be the same size and shape.
5. Both have white flowers winter-spring.

The differences seem to be that the flowers of B. epipsila are profuse and fragrant. B. sanguinea flowers moderately. The leaves of B. epipsila are dark bronze/green on top and red underneath. The leaves of B. sanguinea look much more green in the pictures I've seen.

A larger image would help ID it for sure (short of seeing it in person), but so far my vote is for B. epipsila. Here's a pic of mine. It's not very good, but it's the only one I could find.

{{gwi:439145}}

Elizabeth

i believe that picture is from the ohio state university OPGC site. perhaps you can ask them? after all, part of their mission is to preserve species in cultivation, so if you're willing to grow one...

-ming

Here is a link that might be useful: OPGC begonias--priority genra

Hi,

I have actually never seen any. But thanks to Ming, I was able to find the larger picture of it. Here goes:

They label it B. Sanguinea...

Thanks for letting me know if you know where to find it!!