''Populus tremuloides'' is a

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

tree native to cooler areas of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, one of several species referred to by the common name

aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (C ...

. It is commonly called quaking aspen, trembling aspen, American aspen, mountain or golden aspen, trembling poplar, white poplar, and 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

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...

s, 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 Aspen parkland refers to a very large area of transitional biome between prairie and boreal forest in two sections, namely the Peace River Country of northwestern Alberta crossing the border into British Columbia, and a much larger area stretchi ...

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

in the

Prairie Provinces The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

of Canada and extreme northwest

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...

Description

Quaking aspen is a tall, fast-growing tree, usually at maturity, with a trunk in diameter; records are in height and in diameter. The

bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, e ...

is relatively smooth, whitish (light green when young), 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 A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

on mature trees are nearly round, in diameter with small rounded teeth, and a long flattened petiole. The leaves are green above and gray below. Young trees and root sprouts have much larger ( 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 Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproducti ...

, with separate male and female clones. The flowers are catkins long, produced in early spring before the leaves. The fruit is a pendulous string of 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. Trees as young as 2–3 years old may begin seed production, but significant output begins starting at 10 years of age. Best seed production is obtained between the ages of 50 and 70 years. Quaking aspen grows more slowly in the dry conditions of western North America than it does in the more humid east and also lives longer—ages of 80–100 years are typical, with some individuals living 200 years; the root system can live much longer. In the east, stands decay faster, sometimes in 60 years or less depending on the region.

Name

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 trembling aspen.

Distribution

Quaking aspen occurs across

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

in all provinces and territories, with the possible exception of regions of

Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the '' Nunavut Act'' and the '' Nunavut Land Claims Agreement Act'' ...

north of the James Bay islands. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, it can be found as far north as the northern foothills of the

Brooks Range The Brooks Range ( Gwich'in: ''Gwazhał'') is a mountain range in far northern North America stretching some from west to east across northern Alaska into Canada's Yukon Territory. Reaching a peak elevation of on Mount Isto, the range is b ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

, where road margins and gravel pads provide islands of well-drained habitat in a region where soils are often waterlogged due to underlying

permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...

. It occurs at low elevations as far south as northern

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...

and central

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...

. In the Western United States, this tree rarely survives at elevations lower than due to hot summers experienced below that elevation, and is generally found at . It grows at high altitudes as far south as

Guanajuato Guanajuato (), officially the Free and Sovereign State of Guanajuato ( es, Estado Libre y Soberano de Guanajuato), is one of the 32 states that make up the Federal Entities of Mexico. It is divided into 46 municipalities and its capital city i ...

, Mexico. Quaking aspen grows in a wide variety of climatic conditions. January and July average temperatures range from and in the

Alaska Interior Interior Alaska is the central region of Alaska's territory, roughly bounded by the Alaska Range to the south and the Brooks Range to the north. It is largely wilderness. Mountains include Denali in the Alaska Range, the Wrangell Mountains, and ...

to and in

Fort Wayne, Indiana Fort Wayne is a city in and the county seat of Allen County, Indiana, United States. Located in northeastern Indiana, the city is west of the Ohio border and south of the Michigan border. The city's population was 263,886 as of the 2020 Censu ...

. Average annual precipitation ranges from in

Gander, Newfoundland and Labrador Gander is a town located in the northeastern part of the island of Newfoundland in the Canadian province of Newfoundland and Labrador, approximately south of Gander Bay, south of Twillingate and east of Grand Falls-Windsor. Located on the n ...

to as little as in the Alaska Interior. The southern limit of the species' range roughly follows the mean July isotherm. In the

sagebrush steppe Sagebrush steppe is a type of shrub-steppe, a plant community characterized by the presence of shrubs, and usually dominated by sagebrush, any of several species in the genus '' Artemisia''.chokecherry,

serviceberry ''Amelanchier'' ( ), also known as shadbush, shadwood or shadblow, serviceberry or sarvisberry (or just sarvis), juneberry, saskatoon, sugarplum, wild-plum or chuckley pear,A Digital Flora of Newfoundland and Labrador Vascular Plants/ref> is a g ...

, and hawthorn, forming a habitable haven for animal life. 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.

Ecology

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 heaviestGenetic Variation and the Natural History of Quaking Aspen, Jeffry B. Mitton; Michael C. Grant, ''BioScience'', Vol. 46, No. 1. (Jan., 1996), pp. 25-31. and oldestQuaking Aspen
by the

Bryce Canyon Bryce Canyon National Park () is an American national park located in southwestern Utah. The major feature of the park is Bryce Canyon, which despite its name, is not a canyon, but a collection of giant natural amphitheaters along the eastern ...

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational properti ...

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 protective coating.Ewing, Susan. The Great Alaska Nature Factbook. Portland: Alaska Northwest Books, 1996. The buds and bark supply food for snowshoe hares, moose, black bears, cottontail rabbits, porcupines, deer, grouse, and mountain beavers. The shoots are eaten by sheep, goats, and cattle. Sheep and goats also browse the foliage, as do game animals including elk. Grouse and quail especially eat the buds in winter. Mammals such as beavers and rabbits eat the bark, foliage, and buds. Beavers also store aspen logs for winter food. Other animals nest in aspen groves. The leaves of the quaking aspen and other species in the genus ''Populus'' serve as food for

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sy ...

s of various moths and butterflies.

Dieback

Beginning in the 1990s, North American scientists noticed an increase in dead or dying aspen trees. As this accelerated in 2004, a debate over causes began. No insect, disease, or environmental condition has yet been definitively identified as a 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 Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated ...

. At high altitudes where grasses can be rare,

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...

s 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 Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

, which are not typically browsed. Another possible deterrent to aspen regeneration is widespread wildfire suppression. Aspens are vigorous

resprouter Resprouters are plant species that are able to survive fire by the activation of dormant vegetative buds to produce regrowth. Plants may resprout from a bud bank that can be located in different places, including in the trunk or major branches ( ...

s 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 aspens 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 The mountain pine beetle (''Dendroctonus ponderosae'') is a species of bark beetle native to the forests of western North America from Mexico to central British Columbia. It has a hard black exoskeleton, and measures approximately , about the siz ...

may provide increased opportunities for aspen groves to proliferate under the right conditions. Because of vegetative regeneration by 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 Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

in September 2006 to share notes and consider investigative methodology.

Uses

Aspen bark contains a substance that was extracted by indigenous North Americans and European settlers of the western U.S. as a

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

substitute. 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 preferred species. Aspen wood is used for pulp products (its main application in Canada) such as books, newsprint, and fine printing paper. It is especially good for panel products such as oriented strand board and

waferboard Waferboard belongs to the subset of reconstituted wood panel products called flakeboards. It is a structural material made from rectangular wood flakes of controlled length and thickness bonded together with waterproof phenolic resin under extrem ...

. It is light in weight and is used for furniture, boxes and crates, core stock in plywood, and wall panels.

Culture

The quaking aspen is the state tree of Utah.

References

External links

US Forest Service Fire Effects Information System: ''Populus tremuloides''

* ttp://www.plantmaps.com/nrm/populus-tremuloides-quaking-aspen-native-range-map.php Interactive Distribution Map for ''Populus tremuloides''* Farrar, John Laird. ''Trees In Canada''. Fitzhenry and Whiteside, 1995 * Hickman, James C., ed.
The Jepson Manual: Higher Plants of California
', . University of California Press, 1993. * {{Taxonbar, from=Q469576 tremuloides Trees of North America Taxa named by André Michaux Plants used in traditional Native American medicine