Here is a tiny willow that I found at 8500’ or so on Glacier peak in the Wallowas of northeastern Oregon. It looks like Salix arctica to me but Bonap doesn’t show that it’s even in Oregon. Any other possibilities? The foliage was about 1/2” long and the inflorescences were at most 1” tall. The stems were entirely decumbent, and maybe between one and 2 mm in diameter. I only found this one patch.

http://bonap.net/Napa/TaxonMaps/Genus/County/Salix