According to Kew’s Plants of the World Online (as of December 15, 2017), there are 1,778 accepted species of Begonia. The species have been divided into 60 sections, 16 in East Africa alone. They are native to many countries in mainly tropical and subtropical climates.
There are over 10,000 cultivars…
I am not going into a lot of detail because there is a lot of information online written by experts, which I am not. I just enjoy growing Begonias for their beauty.