BegoniaSpecies.org
B. komoensis is easy grow (terrarium) African epiphyte. (I apologize for the ugly fan obscuring part of the image.) B. komoensis lacks B. polygonoides' succulent leaves, and wilts at humidity levels polygonoides enjoys.
I suspect komoensis would also do well in a warm greenhouse. By warm, I mean one that maintains a temperature above 50° F, 10° C, as many (most?) African species, including polygonoides, suffer fatal injury at lower temperatures. I would very much appreciate any information regarding contrary examples of more cold tolerant African species.
I recently observed with dismay komoensis sold on EBay for extremely high prices, today for $103. This price does not reflect its difficultly in cultivation, or propagation. And it limits access to a species that should be more widely grown. I find that "supply side economics" is not promoting the ideals and aspirations of the American Begonia Society in this instance.
As with most scandent/trailing epiphytes, komoensis roots readily when laid on top of the growing medium in a terrarium.
The mount shown in the image above has a tree fern backing (which is a bad thing, not environmentally sustainable, etc.), previously used by me, sterilized and reused (good things), with a fairly thin top later of long fiber New Zealand Sphagnum moss.
Initially, the Sphagnum and plants are held in place by fishing line and plastic cocktail skewers, source material for endless terrarium tools.(They can be joined and bent with heat.) Soon, root growth secures the Sphagnum moss. I then remove the skewers and fishing line for reasons of aesthetics, and so the fishing line never cuts into a plant. Looking at this photo, I need to go do some of that right now!