General: Bark gray-brown with characteristic warty projections or irregular ridges. A small tree. “[Witches-brooms]” are common. Most common on limestone soils in moist locations. Sometimes mistaken for elm. Wood used principally for furniture, boxes and other containers.
QUAKING ASPEN
(Populus tremuloides)
Leaves: Simple, alternate, 1½″-3″ in diameter, light green, smooth above and below, nearly circular; margins with fine teeth; leaf-stems thin and flattened, causing the leaves to tremble in the slightest breeze. Yellowish-green when unfolding in spring.
Twigs: Slender, reddish brown, smooth, shiny. [Pith] star-shaped, white. Buds sharp-pointed, smooth, shiny, often curved inward.
Fruit: A small (¼″ long) [capsule] containing 10-12 seeds; capsules spirally arranged on a 4″ long drooping stalk, maturing in early summer. Each tiny cottony seed surrounded by long silky threads.
General: Bark thin, pale yellow-green to silvery gray when young, eventually becoming dark brown or gray and rough. A small to medium-sized tree, of rapid growth but short-lived. Often one of the first forest trees to become established on recently burned areas; the most widely distributed tree of North America. Most common in northern Pennsylvania. Wood used chiefly for paper pulp.
BIGTOOTH ASPEN
(Populus grandidentata)
Leaves: Simple, alternate, 3″-4″ long, dark green above, paler below, margins with coarse teeth; leaf-stems flattened; silvery when unfolding in spring.