I was unsure whether to separate this topic from octopetala -where we were talking about this species as well, or piggy-back- if anyone thinks it should be joined they can do so :)
I mentioned that I have seen (if I've id'd correctly!) 3 species of Dryas- drummondii- which is clearly distinct with yellow nodding flowers- octopetala and integrifolia- superficially similar white flowered species- growing in close proximity in the Rockies West/South of here. (I'll dig for some of those pics soon).
Here is what I believe to be D integrifolia (I'll find more pics of this too- just a quick first post before work today) at a site beside Abraham Lake, in the Kootenay Plains region. The plains are considered montane, and are not at a very high altitude- roughly 1100 to maybe 1300 m. This particular site is at the foot of a mountain which reaches down to the man-made lake, and while again not very high, has some alpine plants not seen on the plains generally- presumably the plants are also growing higher up on these mountains, and are able to colonise this lower habitat in open exposed rocky areas.Note the very small, less toothed (integrifolia suggesting 'whole' as in untoothed, though there are still some teeth, but fewer and less visible than on octopetala)and recurved leaves. These plants are very small, and at this site at least, the patches are not large, maybe a foot or so across..