. . "aspen leaves" . "that tree" . . . "Aspen trees" . "aspen trees" . "Quaking Aspen" . "the trees" . "Aspen#Habitat and longevity" . "aspen forests" . . . "Eurasian aspen" . . "Populus tremula" . "Aspen" . "Aspen forests" . . . "aspen tree" . . . . . "poplar" . . . "aspen poplar" . . . . "quaking aspen" . . "trembling aspen" . "''Populus'' sect. ''Populus''" . "Rocky Mountain quaking aspen" . . . . . "aspen" . "Aspen" . "Aspens" . . . "European Aspen" . .