I've read that Dragon Wing begonias are sterile so no seed will be viable if it even makes seed.

This article gives some clues on the background of Dragon Wings although some of the spelling is wrong.

Dragon Wings popularity

Here is what a seed pod should look like and the seeds will be very tiny. The seed pods are off two different begonias - one a cane and the other a rex.

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These are the individual seeds close up. The dimples in the paper towel give a good clue as to how small the seeds are.
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Thank you so much for the information hcmcdole. The article was also interesting. I guess I'll stick to rooting cuttings from mine. They root very easily in water and in potting mix.