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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.)

Part of willow  family Salicaceae.
Uses by native peoples
(Ethnobotany database)   Populus hosts caterpillars of 367 species
of butterflies and moths, in some areas.

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