with . . .

bark=smooth white, black marks;  buds and twigs have white powdered, easily rubbed off
white poplar Populus alba

tree=very tall thin, many small branches
European black poplar Populus nigra

tree=small, bark=light gray (darker at base);  forming colonies;  buds=shiny, against twig
quaking aspen Populus tremuloides
tree=small, bark=light gray (darker at base);  forming colonies;  buds=dusty gray away from twig
big-toothed aspen Populus grandidentata

Learn more about poplar/aspen genus Populus (Populus spp.)

Uses by native peoples
(Ethnobotany database) Populus hosts caterpillars of 367 species
of butterflies and moths, in some areas.
Discover Life Encyclopedia of Life Google Google images Michigan Flora USDA PLANTS db USFS Wikipedia