This is a bit off the topic of gesneriads, but then begonias and gesneriads make for good companion plants. The Potomac Branch of the American Begonia Society has its show and sale this weekend in Alexandria, Virginia. I stopped by this morning to oogle the variety of begonias - from tiny terrarium-grown plants to large shrubby things to the tall canes, from old-time standards to the new and rare. My photos below - but keep in mind that some of the best are missing because I didn't want to be too obnoxious pulling glass domes/lids off everything.
Weather permitting, the show will be open on Sunday from noon until 3:30. They have plants for sale as well. (While you're there, say hi to Johanna who is a brilliant grower and also a member of the gesneriad society.)
The old faithful Dragon Wing:
Begonia heracleifolia - the grower told me this plant's history, from her grandmother and through some rough dormant periods, to how it might be a catnip substitute...:
View down one of the tables:
Begonia 'Sierra Silver Mist':