Populus tremuloides is a deciduous tree native to cooler areas of
North America, one of several species referred to by the common name
aspen. It is commonly called quaking aspen, trembling
aspen, American aspen, Quakies, mountain or golden
aspen, trembling poplar, white poplar, popple, as well as
others. The trees have tall trunks, up to 25 meters (82 feet) tall,
with smooth pale bark, scarred with black. The glossy green leaves,
dull beneath, become golden to yellow, rarely red, in autumn. The
species often propagates through its roots to form large clonal groves
originating from a shared root system. These roots are not rhizomes,
as new growth develops from adventitious buds on the parent root
system (the ortet).
Populus tremuloides is the most widely distributed tree in North
America, being found from
Canada to central Mexico. It is the
defining species of the aspen parkland biome in the Prairie Provinces
Canada and extreme northwest Minnesota.
Aspen is the state tree of Utah.
7 External links
The quaking or trembling of the leaves that is referred to in the
common names is due to the flexible flattened petioles. The specific
epithet, tremuloides, evokes this trembling behavior and can be
literally translated as "like (Populus) tremula", the European
Aspen catkins in spring
Quaking aspen is a tall, fast growing tree, usually 20–25 m
(65–80 ft) at maturity, with a trunk 20 to 80 cm
(8 inches to 2 feet 7 inches) in diameter; records are
36.5 m (119 ft 9 in) in height and 1.37 m
(4 ft 6 in) in diameter.
The bark is relatively smooth, colored greenish-white to gray, and is
marked by thick black horizontal scars and prominent black knots.
Parallel vertical scars are tell-tale signs of elk, which strip off
aspen bark with their front teeth.
The leaves on mature trees are nearly round, 4–8 centimeters
(1 1⁄2–3 1⁄4 inches) in diameter with small rounded
teeth, and a 3–7-centimeter (1 1⁄4–2 3⁄4-inch) long,
flattened petiole. Young trees and root sprouts have much larger
(10–20 centimeters, 4–8 in long) nearly triangular leaves.
Some species of
Populus have petioles flattened partially along their
length, while the aspens and some other poplars have them flattened
from side to side along the entire length of the petiole.
Aspens are dioecious, with separate male and female clones. The
flowers are catkins 4–6 centimeters
(1 1⁄2–2 1⁄4 in) long, produced in early spring
before the leaves; The fruit is a 10-centimeter-long (4-inch)
pendulous string of 6-millimeter (1⁄4-inch) capsules, each capsule
containing about ten minute seeds embedded in cottony fluff, which
aids wind dispersal of the seeds when they are mature in early summer.
The quaking aspen is the State Tree of Utah.
Quaking aspen occurs across
Canada in all provinces and territories,
with the possible exception of Nunavut. In the United States, it can
be found as far north as the northern foothills of the
Brooks Range in
Alaska, where road margins and gravel pads provide islands of
well-drained habitat in a region where soils are often waterlogged due
to underlying permafrost. It occurs at low elevations as far south
Nebraska and central Indiana. In the western United
States, this tree rarely survives at elevations lower than 1,500 feet
(460 m) due to hot summers experienced below that elevation, and
is generally found at 5,000–12,000 feet (1,500–3,700 m). It
grows at high altitudes as far south as Guanajuato, Mexico.
Quaking aspen grows in a wide variety of climatic conditions. January
and July average temperatures range from −30 °C
(−22 °F) and 16 °C (61 °F) in the
to −3 °C (27 °F) and 23 °C (73 °F) in Fort
Wayne, Indiana. Average annual precipitation ranges from 1,020 mm
(40 inches) in
Gander, Newfoundland and Labrador
Gander, Newfoundland and Labrador to as little as
180 mm (7.1 inches) in the
Alaska Interior. The southern limit of
the species' range roughly follows the 24 °C (75 °F) mean
Shrub-like dwarf clones exist in marginal environments too cold and
dry to be hospitable to full-size trees, for example at the species'
upper elevation limits in the White Mountains.
Trembling aspen at sunset
Individual clonal colonies can be discerned during the autumn, as seen
on this mountainside in the
Matanuska Valley in Alaska.
Quaking aspen propagates itself primarily through root sprouts, and
extensive clonal colonies are common. Each colony is its own clone,
and all trees in the clone have identical characteristics and share a
single root structure. A clone may turn color earlier or later in the
fall than its neighbouring aspen clones. Fall colors are usually
bright tones of yellow; in some areas, red blushes may be occasionally
seen. As all trees in a given clonal colony are considered part of the
same organism, one clonal colony, named Pando, is considered the
heaviest and oldest living organism at six million kilograms and
perhaps 80,000 years old. Aspens do produce seeds, but seldom grow
from them. Pollination is inhibited by the fact that aspens are either
male or female, and large stands are usually all clones of the same
sex. Even if pollinated, the small seeds (three million per pound) are
only viable a short time as they lack a stored food source or a
Beginning in 1996, individual North American scientists noticed an
increase in dead or dying aspen trees. As this accelerated in 2004,
word spread and a debate over causes began. No insect, disease, or
environmental condition is yet specifically identified as a joint
cause. Trees adjacent to one another are often stricken or not. In
other instances, entire groves have died.
Many areas of the Western US have experienced increased diebacks which
are often attributed to ungulate grazing and wildfire suppression. At
high altitudes where grasses can be rare, ungulates can browse young
aspen sprouts and prevent those young trees from reaching maturity. As
a result, some aspen groves close to cattle or other grazing animals,
such as deer or elk, have very few young trees and can be invaded by
conifers, which are not typically browsed. Another possible deterrent
to aspen regeneration is widespread wildfire suppression. Aspens are
vigorous resprouters and even though the above-ground portion of the
organism may die in a wild-fire, the roots, which are often protected
from lethal temperatures during a fire, will sprout new trees soon
after a fire. Disturbances such as fires seem to be a necessary
ecological event in order for aspens to compete with conifers, which
tend to replace aspen over long, disturbance-free intervals. The
current dieback in the American West may have roots in the strict fire
suppression policy in the United States. On the other
hand, the widespread decimation of conifer forests by the mountain
pine beetle may provide increased opportunities for aspen groves to
proliferate under the right conditions.
Because of the vegetative regeneration method of reproduction used by
the aspen, where an entire group of trees are essentially clones,
there is a concern that something that hits one will eventually kill
all of the trees, presuming they share the same vulnerability. A
conference was held in
Utah in September 2006 to share notes and
consider investigative methodology.
Typical yellow autumn foliage
Atypical orange and red autumn foliage
Aspen bark contains a substance that was extracted by indigenous North
Americans and European settlers of the western U.S. as a quinine
Like other poplars, aspens make poor fuel wood, as they dry slowly,
rot quickly, and do not give off much heat. Yet they are still widely
used in campgrounds because they are cheap and plentiful and not
widely used in building lumber. Pioneers in the North American west
used them to create log cabins and dugouts, though they were not the
The leaves of the quaking aspen and other species in the genus Populus
serve as food for caterpillars of various moths and butterflies. See
List of Lepidoptera that feed on poplars.
In Canada, quaking aspen wood is used mainly for pulp products such as
books, newsprint, and fine printing paper. It is especially good for
panel products such as oriented strand board and waferboard. It is
light in weight and is used for furniture, boxes and crates, core
stock in plywood, and wall panels.
^ a b c d Quaking
Aspen by the
Bryce Canyon National Park Service
^ a b c "
Populus tremuloides". Germplasm Resources Information Network
Agricultural Research Service
Agricultural Research Service (ARS),
United States Department
of Agriculture (USDA).
^ a b c Perala, D. A. (1990). "
Populus tremuloides". In Burns, Russell
M.; Honkala, Barbara H. Hardwoods. Silvics of North America.
United States Forest Service (USFS), United States
Department of Agriculture (USDA). 2 – via Northeastern Area State
and Private Forestry (www.na.fs.fed.us).
^ a b c d e "technology transfer fact sheet:
Populus spp" (PDF).
Forest Products Laboratory: R&D USDA. Madison, Wisconsin: United
States Department of Agriculture Forest Service, Center for Wood
Anatomy Research. Retrieved 20 September 2010.
^ "Aspen, Quaking (
Populus tremuloides)". Arbor Day Foundation.
^ "S.B. 41 State Tree Change".
Utah State Legislature.
^ Ackerman, Daniel; Breen, Amy (2016-06-06). "Infrastructure
Development Accelerates Range Expansion of Trembling
Aspen ( Populus
tremuloides, Salicaceae) into the Arctic". ARCTIC. 69 (2): 130–136.
doi:10.14430/arctic4560. ISSN 1923-1245.
^ Genetic Variation and the Natural History of Quaking Aspen, Jeffry
B. Mitton; Michael C. Grant, BioScience, Vol. 46, No. 1. (Jan., 1996),
^ a b Ewing, Susan. The Great
Alaska Nature Factbook. Portland: Alaska
Northwest Books, 1996.
^ "How will aspen respond to mountain pine beetle? A review of
literature and discussion of knowledge gaps". Forest Ecology and
Management. 299: 60–69. doi:10.1016/j.foreco.2013.01.008.
^ Kelley, Katie (26 September 2006). "Emblem of the West Is Dying, and
No One Can Figure Out Why". The New York Times.
Media related to
Populus tremuloides (category) at Wikimedia Commons
Data related to
Populus tremuloides at Wikispecies
US Forest Service Fire Effects Information System:
Alberta Forest Genetic Resources Council:
Interactive Distribution Map for
Populus tremuloides". Integrated Taxonomic Information System.
Retrieved 8 August 2006.
Farrar, John Laird. Trees In Canada. Fitzhenry and Whiteside, 1995
Hickman, James C., ed. The Jepson Manual: Higher Plants of California,
0520082559. University of California Press, 1993.
Plant List: kew-5000290