Identifying the Aspen Tree

The trunk and yellow leaves of an Aspen in a forest.

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The aspen tree (Populus tremuloides) is the most widely distributed tree species in North America, ranging from Alaska to Newfoundland and down the Rocky Mountains to Mexico. Utah and Colorado, in particular, are home to the largest portion of the natural acreage of aspen in the world.

Aspen trees are described as an important, community-dependent keystone species within their natural range. They are the most visible of western North American hardwoods, providing understory biodiversity, wildlife habitat, livestock forage, specialty forest products, and highly desirable scenery. Here, we discuss how to identify aspen trees in the forest, as well as growing conditions and common pests.

Description and Identification

A green Aspen leaf against a hand in sunlight.

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Aspen trees go by several different names: trembling aspen, golden aspen, quiver-leaf aspen, small-toothed aspen, Canadian aspen, quakie, and popple. Aspen is the only transcontinental broadleaf tree growing from Newfoundland to California and Mexico.

Aspen trees tend to have rough bark that ranges in color: greenish or yellowish, grey, white, or a mix. These trees are medium-sized, growing between 20 and 80 feet tall. The leaves are circular or triangular, each has a long, flattened stem. The thin, damage-prone bark is light green and smooth with bands of warty bumps. It has commercial value for furniture parts, matches, boxes, paper pulp.​​

This species is often associated with Douglas fir timber, as it is a pioneer tree for fires and logging. The tree has the most wind-sensitive leaves of any broadleaf species, and this is reflected in its common names—the leaves "tremble" and "quake" during moderate winds.

Natural Range

Snow falling on the branches of an Aspen tree.

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Aspen trees grow singly and in multi-stemmed clones over the widest distribution of any native tree species in North America. They occur in pure stands on sandy, gravelly slopes.

The aspen tree is found in Canada, northwestern Alaska, and southeast through Yukon and British Columbia. Throughout the western United States, you are most likely to come across an aspen tree in the mountainous regions of Washington and California, southern Arizona, the Trans-Pecos region of Texas, and northern Nebraska. From Iowa and eastern Missouri, it ranges east to West Virginia, western Virginia, Pennsylvania, and New Jersey. There are also aspen trees in the mountains of Mexico, as far south as Guanajuato.

Silviculture and Management

Care must be taken when transplanting aspen trees, according to the book Native Trees for North American Landscapes written by Guy Sternberg and James Wilson. Any problems during the transplant may cause pests or disease, such as "cankers, insect attack, bark blemishes, and premature death." The authors recommend using root cuttings when establishing the tree in its location.

Common Pests and Diseases

Damaged leaves on an Aspen tree.

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Aspen trees are vulnerable to infection from a number of sources. Common problems include fungal diseases like Cytospora, leaf spots, and other cankers that can cause trunk rot. Insects that plague aspen trees include aphids, sawflies, poplar twiggall flies, and more.

While beautiful trees, aspens are very sensitive to many environmental problems. They host more than five hundred species of parasites, herbivores, diseases, and other harmful agents. As a result, these trees have been a disappointment to many when planted in the landscape.