Quaking aspen (Populus tremuloides) is the most widely distributed tree in North America. It ranges from Atlantic to Pacific, from Alaska and Canada to northern Mexico. In western North America quaking aspen becomes more and more confined to high-mountain habitats as one moves southward. West of the Cascades it inhabits lowlands. Quaking aspen prefers to grow along watercourses, in moist meadows, near seeps and springs and at the edge of conifer forests. In dryer appearing sites such as boulder piles or avalanche chutes or under canyon walls, the presence of quaking aspen often indicates that water occurs a few feet below the surface, particularly in the spring and summer.
Quaking aspen bark is smooth, thin and pale green to white in color. It does not “peel” off in layers like birch bark does. The bark has dark black “eyes” and splotches, which are scars where branches once grew or when the bark was broken. On exceptionally old trees, the lower trunk can be a heavily fissured black or grey.
Winter buds of this Willow Family (Salicaceae) member are small, and slightly resinous with smooth, not downy, reddish scales.
The deciduous leaves are alternate and broadly egg-shaped or oval, finely toothed or entire with an abruptly pointed tip. In summer the upper surface of the leaf is a yellow green while the lower side is a pale silver. Quaking aspen turn a golden yellow in autumn. The petiole (leaf stem) is longer than the leaf blade and flattened. It is attached or hinged to the twig with the blade perpendicular to the flat plane of the stem. The petiole acts as a pivot and even the slightest breeze will set the leaves to quivering. This leaf motion gives P tremuloides its common names, quaking aspen or trembling aspen.
The white wood has a small core of pale brown heartwood. Quaking aspen wood is soft but fine-grained and fairly tough. It has little structural iportance, but is used for fence posts and mine props. It does not splinter so is often used for benches or playground structures. The wood also yields good wood pulp and excelsior. Green quaking aspen logs can be burned without sparks.
Quaking aspen bark is bitter to humans. However, deer, moose, hares, elk, rabbits, bears and porcupines as well as livestock feed on quaking aspen foliage, twigs and bark. Beaver utilize quaking aspen as a preferred food and for constructing their dams.
These pictured quaking aspen were growing on Wheeler Peak in Great Basin National Park (Nevada) and photographed in early October.
In my next post, quaking aspen reproduction.