Wahlgreniella Hille Ris Lambers
For many years I and a colleague have thought about working up a paper on this genus, trying to resolve the species-level taxonomy of the group. But, between time demands to do this, and the fact that each year I seem to find some samples that complicate the picture, I have not done anything with it. You can see in my collection database how many plants I have collected this genus from. Just one example: in September of 2014 I was collecting in the mountains of the Lincoln National Forest (New Mexico), and was walking through the mountain-top solar observatory site called Sunspot (about 2800 meters elevation), through a windy blowing fog. On the highest parts of the mountain grows a rose, with strange morphology, that I have never seen elsewhere and on it was a Wahlgreniella that looked different from anything I have seen before. The photos I have are of the mundane forms in the lowlands.