Aspen (tree)

Aspen (tree), common name for certain related trees (see Poplar), particularly the so-called quaking aspens, several species of which have the petioles, or leafstalks, laterally compressed so that the leaves can move easily from side to side but not up or down. A breeze sets all leaves of one of these trees into motion. The most familiar species are the aspen native to Europe, western Asia, and northern Africa; the American aspen, found in North America; and the large-toothed aspen, found in eastern Canada and the United States.

Scientific classification: Aspens belong to the genus Populus, of the family Salicaceae. The aspen is classified as Populus tremula, the large-toothed aspen as Populus grandidentata, and the American aspen as Populus tremuloides.