A volunteer in my backyard this year. I see full-grown plants in the neighborhood, so I know it will get to be a large plant.
The leaves fold up in low light, and the flowers- at least on this immature plant- hang down. I couldn't get a clear bloom photo, but can try again tomorrow.
The plant database entry for S. bicapsularis says that it blooms late fall to winter, though, and this puppy is blooming now. The entry also says its only hardy to 9b, but I know this plant is hardy here in unprotected sites in 8b/9a.
I know there are other plants in this family that are similar-looking; any alternate ID suggestions, or did I get it right the first time?
Thanks for having a look,