Populus tremuloides (Quaking aspen): Leaves
		The 1.5- to 3-inch-long, smooth leaves are nearly round, with small, irregularly-toothed margins. They are smooth and dark green above; paler with a whitish bloom underneath. Fall color is bright yellow. The slender, vertically flattened petioles are up to 3 inches long. They cause the "quaking" or "trembling" motion that gives the tree its common names.