Thanks for starting this new species topic! I would think too that the photos you've posted in the first set are D. integrifolia
... although it would be great if an expert could chime in and confirm it.
A couple of the ones in the second set are a little too small to examine really closely. This reminds me that I should probably go back yet again through all of my white-flowered Dryas
photos... I think I have a lot of somewhat intermediate forms that may or may not be hybrids! Needless to say, I'm not sure where the tipping point is between variability within a species and what might be a hybrid. Flora of Alberta
: "leaf-blades lanceolate-oblong, 0.8-1.5cm long, broadest below the middle, the margins entire or with a few teeth in the lower half and usually somewhat revolute; the base cordate or truncate, the upper surface usually glabrous and not rugose, the lower surface thinly white-tomentose, the non-prominent midvein lacking glandular-stipitate dark hairs".D. octopetala
: "leaf-blades oblong-ovate, 0.8-2.5cm long, the margins coarsely incised-crenate and somewhat revolute, the base subcordate or rarely truncate, obtuse at apex, the upper surface strongly rugose, with wart-like excrescences or merely glandular-viscid, the lower surface white-tomentose between the prominent veins; the veins, also the petioles and stipules, covered with yellowish brown glands".
NB: Here's a mini glossary paraphrased from Flora of Alberta
entire: with smooth margins, e.g. a leaf that is not toothed, cleft or lobed
revolute: rolled downward from the margins or apex; in this case, the leaves are rolled under along the edges
cordate: heart-shaped with the point upward
truncate: with the base straight or nearly so, as if cut off
tomentose: covered with short hairs that are matted
Flora of Alberta also says that the two species hybridize to form "plants with leaves smooth and shiny above but the margins crenate-serrate".
Here's a close-up of one that I thought was D. integrifolia
, from Forgetmenot Ridge, where large mats of it are interspersed with mats of D. octopetala
... (and I would imagine there would be the potential for many hybrids there):