This single-trunked tree is usually 30-60' tall, although specimens up
to 70-100' are known to occur (see photo of Small
trunk is normally ½-1½' in diameter
(rarely up to 3' across), relatively narrow, and straight. The crown is
narrowly rounded with ascending to spreading branches. Trunk bark is
variable, depending on the age of a tree. On a mature tree, the bark at
the base of the trunk is coarse, gray, and furrowed, becoming more
smooth and light-colored above. On immature trees, the trunk bark is
white to light yellowish gray and relatively smooth; there are usually
black horizontal rings and scattered black knots along the trunk. The
bark of larger branches is similar in appearance to the trunk bark of
immature trees. Small branches are light brown and warty from abundant
lenticels, while twigs are light to dark brown and glabrous. Young
shoots are light
green or yellowish green and glabrous. Alternate leaves occur along the
twigs and young shoots. Individual leaves are 1½-3" long and a little
less across; they are oval-ovate in shape with 18-40 small teeth along
each side of their margins. These teeth are crenate-dentate. The upper
leaf surface is medium green and glabrous, while the lower surface is
pale green and glabrous. The petioles are 1½-3" long, light green or
pale yellow, and flattened, enabling the leaves to flutter in response
to every breeze.
Quaking Aspen is usually dioecious, producing either
all male (staminate) catkins or all female (pistillate) catkins on
trees. However, a small minority of trees produce catkins with perfect
florets. These catkins are about 1½-2½" long and drooping. Each floret
of a male catkin consists of 5-10 stamens with glabrous filaments that
develop from a shallow cup-shaped disk. The upper rim of the disk is
oblique. There is also a brown floral bract that is narrowly lobed and
hairy along its upper side. Each floret of a female catkin consists of
a naked pistil that develops from a shallow cup-shaped disk. The upper
rim of the disk is oblique. The pistil is 3-6 mm. long and
lanceoloid with bifurcated stigmata at its apex. There is also
a brown floral bract that is narrowly lobed and hairy along its upper
side. The blooming period occurs during mid-spring for about 1-2 weeks
before the vernal leaves unfold. The florets of the catkins are
cross-pollinated by the wind. During the early summer, the female
catkins become up to 4" long and their seed capsules split open, to
release their seeds. Each capsule contains 4-10 tiny seeds that are
embedded in cottony hairs. The seeds are distributed by the wind or
water. The root system is relatively shallow and widely spreading.
Clonal offsets often develop from the lateral roots. As a result,
colonies of clonal trees are commonplace. The deciduous leaves turn
golden yellow during the autumn.
The preference is full sun, moist to dry-mesic conditions,
and a relatively loose soil containing sandy loam or silty loam.
However, this tree also adapts to soil containing gravel or clay. Hot
dry weather during the summer is stressful to this tree. Growth and
development are fairly rapid during the first 20 years of life, after
which this tree grows more slowly. An individual tree is relatively
short-lived (up to 50 years), however a clonal colony of Quaking Aspen
can persist for hundreds and perhaps thousands of years. The tiny seeds
remain viable for only 1-2 weeks.
Outside of cultivation, the native
Aspen is occasional in northern Illinois, rare in central Illinois, and
absent from the southern section of the state (see Distribution
This tree has a large range in the boreal region of North America.
Habitats include upland woodlands, sandy woodlands, sandy savannas,
sandy thickets, woodland edges, edges of marshes, bogs,
riverbanks, borders of lakes, and abandoned sandy fields.
Quaking Aspen is a pioneer species that prefers disturbed habitats,
especially burned-over areas. It is able to resprout from its root
system after a fire. Quaking Aspen sometimes becomes the dominant tree
in these habitats, although it is eventually replaced by other trees in
the absence of a regimen of disturbance. Quaking Aspen is occasionally
cultivated as a landscape tree for its attractive bark and foliage.
Many insects feed on the leaves, bore
wood, or suck juices from Quaking Aspen and other Populus spp
(Aspen Leaf Beetle), Chrysomela scripta
(Cottonwood Leaf Beetle), and many other leaf beetles (see Leaf Beetle
) that feed on the foliage. The larvae of some beetles
through the wood of either living or dead trees. These species include
(Poplar Twig Borer), Oberea
(Poplar Borer), Descarpentriesina cyanipes
(Eastern Poplar Buprestid), and Dicerca
Borer). Other insect feeders include the plant bug Orthotylus
(Spotted Poplar Aphid) and Chaitophorus
(Poplar Leaf Aphid), the leafhopper Kybos copula
(see the Insect Table
listing of these species). Caterpillars of such butterflies as
(Mourning Cloak), and Nymphalis vau-album
(Compton Tortoiseshell) feed on the leaves of
Quaking Aspen and
other Populus spp.
as do caterpillars of the skipper Erynnis
(Dreamy Duskywing). In addition to these species, the caterpillars of a
large number of moths feed on the leaves and other parts of these trees
(see Moth Table
(Virgin Moth), Pseudosciaphila
(Spotted Aspen Leafroller), and Phyllonorycter
Many vertebrate animals use Quaking Aspen and other
as a source of food, protective cover, and nesting
habitat. The Ruffed Grouse, Greater Prairie Chicken, and Purple Finch
feed on either the buds or catkins, as does the Red Squirrel. The
Yellow-Bellied Sapsucker drills holes into the thin bark to access the
sap. White-Tailed Deer, Elk, and the Cottontail Rabbit browse on the
twigs and foliage of young trees. Such domesticated animals as cattle,
sheep, and goats also browse on the twigs and foliage. When Quaking
Aspen grows along bodies of water, its bark, branches, and foliage are
eaten by the Beaver and, to a lesser extent, by the Muskrat. The Meadow
Vole also feeds on the bark below the snow line during winter.
Insectivorous birds often visit aspen groves to feed on the many
insects that these trees attract. Many birds construct nests on the
branches or in the cavities of this tree, including the Red-Breasted
Nuthatch, Yellow Warbler, Warbling Vireo, and Northern Flicker. Beavers
use the branches of Quaking Aspen in the construction of their dams and
Along the sandy bank of a pond
powerline clearance at the Indiana Dunes National Lakeshore in NW Indiana.
Quaking Aspen has attractive foliage, bark, and autumn
coloration. The wood is light, soft, and straight-grained. It has been
used to make pulp for paper, particle board, strand board, and plywood.
Because the wood doesn't splinter readily, it has also been used to
make toothpicks, sauna benches, and wooden structures for playgrounds.
Quaking Aspen can be distinguished from similar Populus spp.
shape of its leaves, the abundance of small teeth along its
leaf margins (18-40 per side), its flattened petioles, and
bark. It is similar to Populus
(European Aspen), but the leaves
of the latter have fewer and larger teeth along their margins.
Occasionally, Quaking Aspen forms naturally occurring hybrids with
other Populus spp.
although such hybrids are relatively rare in