That looks like a tuberous begonia to me. Fibrous or waxed begonias have a round leaf and to my knowledge do not come in yellow. Fibrous or waxed begonias with a bronze leaf can take more sun then the plain green leaf type. Buy fibrous begonias next time. When I plant new stuff in the sun I partly shade it until it gets it's feet in. A little wire table, sun cloth on a couple of stake or a window screen against a stake. It's not to late to get the right ones in.

Tuberous begonias are shade plants. An eastern exposure with mid day protection is best for them. Yes I think you are burning up this little yellow begonia. Dig her up and put her in a pot. Your little tuberous begonia will rot with too much water. I like them in a pot with a little fern at their back and a lamium trailing down the front of the pot. Tuberous begonia can be wintered over and will come back the next year, thatâÂÂs how I got hooked. They come in different sized plants and you may need to stake it. It will take time to recover. They like to be fed.

This is my big yellow tuberous begonia.
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This is a fibrous bronze begonia in a pot with a big pink tuberous begonia. Notice the tuberous begonia has a pointed leaf.
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I love all begonias, cane, fibrous and tuberous. Fibrous begonias are perennial here. I seemed to have lost a lot this winter. They are not resistant to men that replace driveways, drat!

It appears we are each half right. It is a hybrid between a wax and tuberous begonia (begonia hiemalis).

I can easily move these to replace the dying cool-season monkey flowers and pansies in my containers that get much more shade.

Thanks for the info!

This is a link to what I have according to my tag: http://www.imagebotanica.com/index.cfm?fuseaction=stock.detail&itemID=5151

Here is a link that might be useful: More info

Interesting article, but I have my doubts. In spite of those shiny green leaves semperflorens (wax) begonias are not listed as being crossed into the hiemalis (Riegers). The Thompson Begonia book, the bible of the Begonia Society,has several paragraphs on the development of the hiemalis, no mention of semps. Whatever you call them, grow and enjoy.

Rieger Begonia are a cross with the wax begonia. They seem to require the same environment as a tuberous begonia, shade, warmth but don't do well in heat or to much moisture. I am guessing the result of the cross was to get a begonia that will bloom year round. They are called winter blooming begonia. I haven't had one because I thought it was a house plant. On another sight they are planting them out side and some times kill them but are still happy and will try again. They are said to be finicky and worth the trouble. I will have to try one.
Don't tell me the monkey plant is going to die! Just started monkeying around with them! Bought one last spring and it took over the pot last winter. Got a nice show this spring, topped them and waiting for encore.

It just gets too hot here to try to keep monkey flowers going all summer. They start to look bad by this time of year here when we get daytime highs into the 90s and high humidity. They really put on a great show through April and May though. I will probably get some for fall.

As for the begonias, when I pulled them up, they appeared to be tubers. The tag really doesn't tell me anything other than Red Fox Blitz Begonia that then took me to that posted link when I searched for it. Either way, they were getting too much sun and are recovering now in the shade. It is funny because I can't get spring bulbs to grow there due to lack of light, but by June the area gets a solid 5-6 hours of sun.