There is perhaps no tree species in North America which is more recognized than quaking aspen (Populus tremuloides), especially in the western United States. Although quaking aspen is the most widely distributed tree species on the continent, its popularity is more the result of the tree's uniquely beautiful characteristics. The autumn foliage of quaking aspen is, without doubt, the most magnificent in all of the Rocky Mountains, and for that matter, throughout western North America. Even more notable, though, is the unmistakable sound of chattering aspen leaves. Even the softest of mountain breezes is enough to persuade the leaves into the "trembling" whisper which has given quaking aspen its name.