The Populus Tremuloides is commonly known as the Aspen, Quaking Aspen as well as Trembling Aspen.
The scientific name of quaking aspen is Populus tremuloides Michx. (Salicaceae) . There are no currently recognized subspecies or varieties . Roland and Smith recognize a form with extremely broad leaves, P. tremuloides forma reniformis Tidestr., that occurs in northeastern North America. Quaking aspen is in subsection Trepidae of the genus Populus. Some authorities consider the Trepidae aspens a single taxonomic entity. Under this treatment, quaking aspen, bigtooth aspen (P. grandidentata), European aspen (P. tremula), and three aspens occurring in Asia are classed together as a single, circumglobal superspecies . Quaking aspen hybridizes naturally with bigtooth aspen and white poplar (P. alba), a naturalized European species. Hybrid quaking aspen-bigtooth aspen swarms occur in the Niobrara River valley of Wyoming and Nebraska , and quaking aspen-bigtooth aspen hybrids are common in some eastern locales . Black cottonwood (P. trichocarpa)- quaking aspen hybrids occur rarely in Alaska . Quaking aspen has been crossed with several Populus species, particularly the Eurasian species gray poplar (P. canescens), European aspen, and white poplar, in tree breeding programs .Quaking aspen is the most widely distributed tree in North America. It occurs from Newfoundland west to Alaska and south to Virginia, Missouri, Nebraska, and northern Mexico. A few scattered populations occur further south in Mexico to Guanajuato . Quaking aspen is distributed fairly continuously in the East. Distribution is patchy in the West, with trees confined to suitable sites. Density is greatest in Minnesota, Wisconsin, Michigan, Colorado, and Alaska; each of those states contains at least 2 million acres of commercial quaking aspen forest. Maine, Utah, and central Canada also have large acreages of quaking aspen .Quaking aspen is a major cover type in North America. In Minnesota, Wisconsin, and Utah, quaking aspen occupies more land than any other forest type. Quaking aspen also occurs in a large number of other forest cover types over its extensive range. It is common in spruce-fir (Picea-Abies spp.) types of the Great Lakes States and central Canada and in mixed northern hardwoods. Mixed jack pine (Pinus banksiana) and quaking aspen occur on the Precambrain shield in Canada and Minnesota. In the Rocky Mountains, quaking aspen groves are scattered throughout Engelmann spruce-subalpine fir (Picea engelmannii-A. lasiocarpa) forests. Quaking aspen is common in mixed conifer forests of New Mexico, Arizona, and California. At its lower altitudinal limit in the western United States, quaking aspen is associated with scrub oaks (Quercus spp.) or sagebrush (Artemisia spp.). Prostrate quaking aspen occur above timberline . Throughout its range, quaking aspen occurs in mid- to upper riparian zones . Quaking aspen is listed as a dominant species in over 100 habitat, plant community, and vegetation typings. A comprehensive list of these publications can be obtained by using the Citation Retrieval System (CRS). In CRS, a combination search using the keywords POPTRE and HTS (Populus tremuloides and habitat types), and a second search using the keywords POPTRE and COMM TYPES (P. tremuloides and community types), will produce a list of habitat, plant community, and vegetation typings describing quaking aspen as a dominant species. The search can be narrowed by including the keyword for the state or administrative unit of interest (e.g., search: POPTRE and HTS and CO). Associated shrub species: East - Shrub species commonly associated with quaking aspen in the East include beaked hazel (Corylus cornuta), American hazel (C. americana), mountain maple (Acer spicatum), speckled alder (Alnus rugosa), American green alder (A. viridis spp. crispa), dwarf bush-honeysuckle (Diervilla lonicera), raspberries and blackberries (Rubus spp.), willows (Salix spp.), and gooseberries (Ribes spp.). Great Plains - Additional species occurring with quaking aspen in the prairie provinces included snowberry (Symphoricarpos spp.), highbush cranberry (Viburnum edule), limber honeysuckle (Lonicera dioica), red-osier dogwood (Cornus sericea), western serviceberry (Amelanchier alnifolia), chokecherry (Prunus virginiana), Bebb willow (Salix bebbiana), and roses (Rosa spp.). Alaska - Bebb willow and roses are also associated with quaking aspen in Alaska. Other common shrub associates are Scouler willow (S. scouleriana), bearberry (Arctostaphylos uva-ursi), mountain cranberry (Vaccinium vitis-idaea), and highbush cranberry. Rocky Mountains - Mountain snowberry (Symphoricarpos oreophilus), western serviceberry, chokecherry, common juniper (Juniperus communis), Oregon-grape (Berberis repens), Wood's rose (R. woodsii), myrtle pachistima (Pachistima myrsinites), redberry elder (Sambucus pubens), and a number of Ribes species are associated with quaking aspen in the Rocky Mountains . Pacific Northwest - In valleys west of the Cascades in Oregon and Washington, quaking aspen alternates dominance with Douglas hawthorn (Crataegus douglasii). Quaking aspen grows through the Douglas hawthorn overstory, resulting in reduced vigor of Douglas hawthorn. Quaking aspen eventually dies back, releasing Douglas hawthorn in the understory . Associated herbaceous species: East - Herbs commonly found in the understory of quaking aspen in the East include largeleaf aster (Aster macrophyllus), wild sarsaparilla (Aralia nudicaulis), Canada beadruby (Maianthemum canadense), bunchberry (Cornus canadensis), yellow beadlily (Clintonia borealis), roughleaf ricegrass (Oryzopsis asperifolia), sweet-scented bedstraw (Galium triflorum), sweetfern (Comptonia perigrina), lady fern (Athyrium filix-femina), bracken fern (Pteridium aquilinum), sedges (Carex spp.), and goldenrods (Solidago spp.). West - The herbaceous component of quaking aspen communities in the West is too diverse to list. Forbs dominate most sites .Some of the information provided here is attributed to:Howard, Janet L. 1996. Populus tremuloides. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). , available at the USDA Fire Effects Information System (FEIS) website