I think there are a few other new additions not listed above
Begonia Culture, Care, Vendors & Links to Begonia Related sites
In this thread, you will find a list of member contributed and compiled information and internet links pertaining to Begonias, their care, culture and much more. This thread is for everyone who whishes to know more about about Begonias.
Culture & Care
General Care and Information by Brad Thompson
One of the best jumping off places is Brad Thompson’s newly revised web site. His cultivars are now being sold by Kartuz Nursery (see link in the vendor section).
This is a super web site with just about everything you could want to know about begonias. http://www.bradsbegoniaworld.com/
Begonia Culture, covering show classification, growing, propagation and pollination