Rosa virginiana X arkansana

I'd guessed that this particular seedling might turn out to be a white-flowered one, because the stems of the plant are green rather than reddish like its siblings. Sure enough it's white. I'll bet it would have looked even prettier if I'd gotten to see it before the heat and thrips took their toll. Although I've read about them, this is the first white flowered type I've seen among the North American tetraploid species and their hybrids.