with petiole=___ flat  or  petiole=◯ round :

Petiole=___ flat

blade base=___ flat, teeth=very small (>5/cm) (>12/in), tree very tall thin
🇪🇺 European black poplar  Populus nigra

blade base=___ flat, teeth=medium (2-3/cm) (5-8/in)
eastern cottonwood  Populus deltoides

blade base= rounded (U-shaped), teeth=few+large, leaf longer than wide
big-toothed aspen  Populus grandidentata

blade base= rounded (U-shaped), teeth=small, leaf about as long as wide
quaking aspen  Populus tremuloides

Learn more about aspen/​cottonwood/​poplar genus Populus

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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