Illinois Natural History Survey - University of Illinois

Quaking Aspen (Populus tremuloides Michx.)


Photos by Kenneth R. Robertson, INHS



Quaking aspen is a medium-sized, shade intolerant tree that attains heights of 40-70 feet (12-21 meters), and diameters of 1-1.6 feet (0.3-0.5 meters). This tree has a short, rounded crown, and trunks up to about 23 inches (60 cm) wide. Young trees have smooth chalk-white to yellow-green bark. With age, the bark becomes thick, roughened by warty bands, and divided into flattened ridges. Branches are slender and slightly drooping, with hairless red-brown twigs during the first season. Leaves are alternate, deciduous, simple, and broadest near the ovate to heart-shaped base. They are 0.8-3 inches (2-8 cm) long and 0.7-2.8 inches (1.8-7 cm) wide. A short pointed tip found on each leaf has 20-40 pairs of fine teeth along the edges. Leaves are a dark shiny green above and a dull green beneath, and turn golden in autumn. The tree obtained its name because the leaves flutter in the slightest breeze due to long, flattened, slender leafstalks. qaspen1.gif

Similar Species

Quaking aspen is distinguished from other aspens, poplars and cottonwood by its finely toothed, ovate leaves that lack a white felt of hairs on the under surface and by its whitish bark. Big-tooth aspen has coarsley toothed, nearly circular leaves and bark that is grayish-green. White poplar, an alien tree, has coarsely toothed, ovate leaves that are covered by a white felt of hairs on the lower surface and has grayish-whitish bark. Cottonwood has triangular leaves that are nearly flat across the bottom and gray bark. Quaking aspen should be accurately identified before attempting any control measures. If identification of the species is in doubt, the plant's identity should be confirmed by a knowledgeable individual and/or by consulting appropriate books.

Quaking aspen has one of the widest distributions of any tree in North America. This aspen can be found from northern Alaska to Newfoundland, south to Pennsylvania, Missouri, northern Mexico, and lower California. In Illinois, it is recorded from 38 counties and is most common in the northern half of the state.

This tree grows in many diverse soils, including shallow rocky soil, clay soil, rich soil, or nutrient deficient sandy soil. Best growth occurs in rich, porous, limy soils.

Life History
This rapidly growing tree is one of the most aggressive of the pioneer species. It quickly colonizes recently burned or bare areas and soon establishes dense stands of young trees. Quaking aspens reproduce sexually by seeds and asexually by sending suckers from their extensive lateral roots, forming stands that are clones. Apparently establishment of quaking aspen by seed is uncommon. Establishment of stems by root suckering is much more common. Quaking aspens begin to produce seed at 15-20 years of age and continue for about 50 years, although good seed crops are produced only every 4-5 years. Flowers or catkins appear in April and May before the leaves, and fruits ripen 4-6 weeks later. Male and female catkins grow on separate trees and reach lengths of 2.5-10 cm. Fruit is in elongated clusters of drooping catkins with 0.2 inch (6 mm) long, light green capsules, each of which contains numerous seeds with cottony hairs that allow the seeds to become airborne. Rarely, trees live to be 150 years old.

Effects Upon Natural Areas
Aspen is a problem in some disturbed prairie areas where it forms large clones. It tends to exclude prairie species and provides favorable conditions for other trees and shrubs to become established.

Illinois Natural History Survey

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