A couple come to mind, Bs. herbacea and lanceolata, and I think there are 3 or 4 more considered close to being epiphytic (although many growers refer to these as epiphytic begonias). They look pretty much alike and the growing conditions for all are similar. Mike Kartuz, the commercial grower, used to grow his in one of those green net strawberry boxes in sphagnum and sold them that way. Sounds like you live in a good area to experiment with these.Took a quick look at an old catalog, Bs. velloziana and squamulosa are two others. Don't know where you can buy them, however, B. U455 is another and is sold on Ebay.

Woebegonia, a very delayed thanks for the information! After talking to Kartuz I decided to experiment with the more drought tolerant terrestrials rather than the more moisture loving epiphytes.

Here's a photo of Begonia boliviensis growing on my tree. You can click on the photo for a more detailed description of how I'm growing it...

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In this photo...if you look hard enough...you can see Begonia ruhlandiana growing epiphytically.

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Like the boliviensis it went completely deciduous during the winter...but the ruhlandiana sent out new leaves way way after the boliviensis. That's not a very good sign.

Begonia peltata is very happy growing on my Pygmy Date Palm. Does anybody know if it's ever been crossed with boliviensis? Is that even possible? I just made the cross but haven't sowed the seeds yet.

Lucky you,to live so close to Kartuz, for advice. Both boliviensis and peltata are from So.America, so I would think there is a chance they will cross, you might tryboth ways too. Your boliviensis is beautifully grown, mine never blooms that much for me, in fact I am still watching for the first bloom of this season to open.

I wished I lived closer to Kartuz! He's easily got the best selection of tropical plants here in Southern California.

I crossed the two species both ways. Some of the boliviensis pods have already ripened while the peltata pods might start ripening next week. The boliviensis pods are kind of tricky though because they open before I expect them to. One day they look green with perhaps the wings brown...and then the next day they are brown and open! Admittedly, I have to climb the tree to see if they are ready so it's not something I do every day.

Initially I planned on sowing the seeds directly on the tree...but now I plan on sowing the seeds on 10" sections of old trellis wood covered in New Zealand sphagnum moss. I'll place the sections of wood horizontally on top of bark that's in rectangular plastic planters covered in clear plastic and under grow lights in my garage.

After the seedlings germinate I'll take them out of the planters and hang them vertically in my shade cloth area. My primary interest is drought tolerance so I'll water them just enough so that only a few seedlings survive on each mount. Not sure how much drought tolerance variation there will be between seedlings.

If you're still waiting for your first boliviensis bloom of the season...have you thought of growing them from seed and selecting the early bloomers? You could keep the early bloomers and sell off the rest.