Beautiful tree with distinct pointed leaves with "white" undersides...not sure if this was the "European" species though....needs further research...
Pt. 1, 8515 ft, in Ponderosa Pine-Douglas-fir-Aspen forest.
An explanation of this elevational transect can be found with this observation:
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar /ˈpɒp.lər/, aspen, and cottonwood.