We made a brief stop recently in north-central Washington to see a patch of the Columbia Hybrid Lady's Slippers, Cypripedium x columbianum, a natural hybrid of the Mountain Lady's Slipper, Cypripedium montanum and the Yellow Lady's Slipper, Cypripedium parviflorum var. pubescens. In this hybrid population, which grows mixed together, there are flowers that look like both parents, with either a yellow or white lip, as well as flowers that are clearly intermediate between the parents, the lips a soft yellow or off-white color. When we visited this patch, it was obvious that it had not been a very good year with fewer than normal plants and we also found most of them finished, though we did take enough photos for a blog post.
Cypripedium x columbianum