Kingdom: Plantae

Phylum: Magnoliophyta -- flowering plants

Class: Magnoliopsida -- dicotyledons

Order: Salicales

Family: Salicaceae -- willow

Infraspecific Taxa: Some authors recognize infraspecific taxa, but most do not.

Common Name: quaking aspen

Species Code: POTR5

Origin: Native to riparian areas and moist places over much of North America except the southeastern US. On the Palouse it is usually found in riparian areas and on moist north facing slopes.

Rare: no

Form: tree, deciduous, to 15 m tall, forming colonies from rhizomes; bark whitish becoming black and rough on older trees; bud scales smooth, only slightly resinous.

Mature height: to 50 feet

Duration: perennial

Longevity: medium lifespan

Habitat Type: riparian areas, shrub thickets

Wetland Indicator Status: not listed

Leaves: alternate; petioles laterally flattened; blades broadly ovate to reniform-cordate, petiolate, 2.5- 9 cm long by 2.5-8 cm wide, shortly acuminate to apiculate, green above, paler and glaucous beneath, margins finely toothed or wavy, white-ciliate.

Flowers: plants dioecious; flowers borne in a pendant catkin (ament), precocious; perianth lacking, each flower subtended by a scale; staminate catkins 2-3 cm long, soon deciduous; pistillate catkins 4-10 cm long.

Flower color: inconspicuous

Bloom: April

Fruit: capsule; seeds small, lacking endosperm, covered with long white hairs.

Characteristics:
Reproduces both sexually by seed and vegetatively from root suckers. Single clones may occupy a large area.
Range of 2,500,000 to 3,000,000 with an average of 2,750,000 seeds/lb (Wyckoff & Zasada undated).
Catkins are precocious.
2n=38 (University of British Columbia 2003, Baldwin et al 2004).
Wind pollinated.
Plants are generally dioecious, although a few perfect flowers are sometimes produced on individual plants and some plants may produce both staminate and pistillate flowers.
Diploids only are known.
Wood is used for pulp and fiber.
Fruit is a capsule.
Seeds are mostly wind dispersed but can also be dispersed by water.
Many parts of the plant are used by a variety of wildlife. Plants also provide cover and habitat for many species of wildlife.
Rocky Mountain elk use the plants throughout the year (Kufeld 1973).
Sheep, cattle, and wildlife browse the plants and birds eat the seeds (Stubbendieck et al 1997).
The poplar and willow borer, Cryptorhynchus lapathi, a weevil introduced from Eurasia, attacks many species of poplar and willow. Larva bore into the stem and weaken them, causing breakage or death (Broberg et al 2002, Broberg et al 2005).
Cytospora canker is a disease caused by the fungus Cytospora chrysosperma. Symptoms are an orange liquid oozing from the stem, and orange colored dead bark (Jacobi 2006). Cankers usually appear in the upper portion of a shoot and move downward. Shoots under moisture stress are the most susceptible to infection. (Bloomberg 1962). Cytospora canker enters the stem through existing wounds to the bark. Willows (Salix spp.) and poplars (Populus spp.) are most susceptible.
3,248,000 seeds/lb (USDA NRCS PLANTS Database 2010).
Populus species may be hosts for the larva of the persius duskywing (Erynnis persius), the mourning cloak (Nymphalis antipoa), Lorquin’s admiral (Limentis lorquini), and the western tiger swallowtail (Papilo rutulus) butterflies (Pocewicz 2005).

Sun requirement: full

Soil moisture: mesic

Precipitation: 20-40 inches (USDA NRCS PLANTS Database 2010).

Fire: Tops are killed by fire, but roots are highy resistant and sprout vigorously after fire. Often becomes the dominant species following fire and can develop a complete stand within 10 years (Howard 1996).

Sowing time: spring

Transplant time: spring or fall

Stratification: none required

Seed yield: high

Seed harvest: difficult

Seed cleaning: medium difficulty

Planting duration: medium

Seed insect problem: no information available

Seed shatter: high

Seed size: small

Seed harvest date: April?

Seed comments: seed is windborne

Herbaria: Specimen data and digital resources from The Consortium of Pacific Northwest Herbaria

Keywords: native perennial upland tree

Propagation:
8 protocols in the Native Plants Network
root cuttings, Glacier National Park, Montana
Colorado State Forest Service Nursery, Fort Collins, CO
Los Lunas New Mexico Plant Materials Center
seed, Glacier National Park, Montana
University of Kentucky
J. Herbert Stone Nursery, Central Point, Oregon
J. Herbert Stone Nursery, Central Point, Oregon
Coast to Coast Reforestation, Edmonton, Alberta

Other Propagation Information:
Seed pretreatment not required, but needs light to germinate (Hudson & Carlson 1998).
Fresh seed germinates readily under a variety of temperatures from 5-29^oC when sufficient moisture is provided. Seeds will germinate when submerged. Seeds are short lived but viability can be prolonged by drying fresh seed for 3-8 days and storing at 5^oC. Germination is not light dependent. pH should be between 7 and 8.5 (Faust 1936).
Seeds are short lived (2-4 weeks), but low humidity and low temperature increases longevity. Seed establishment in the wild occurs only when wet conditions last for at least a week (Moss 1938). Seeds are nondormant, but need a wet substrate. Seeds will germinate in the dark (Perala 1990).
Cuttings easiest, but grows readily from seed (Kruckeberg 1996).
Seed should be planted in a water saturated seedbed. Grows readily from lateral root cuttings (Rose et al 1998).
Greenwood cuttings can be rooted under mist (Farmer 1963).
Seed is non-dormant but must be kept moist during germination and early seedling growth. Germination is equally high at temperatures ranging from 2 to 30^oC. Seeds will germinate in the dark but are not able to emerge from planting depths greater than 6 mm. Seed stored at minus 5^oC retained high germination for 48 weeks (McDonough 1979).
Reproduces both sexually by seed and vegetatively from root suckers. Single clones may occupy a large area.

Notes: Aggressively suckers from rhizomes and is therefore not suited to formal landscapes, but is a excellent plant for restoration and for natural areas (Idaho Native Plant Society 1999).

References:
Baldwin, B.G., S. Boyd, B.J. Ertter, D.J. Keil, R.W. Patterson, T.J. Rosatti, and D.H. Wilken (eds). 2004. Jepson Online Interchange for California Floristics. University and Jepson Herbaria, University of California, Berkeley, CA. Accessed 1/1/10 online at http://ucjeps.berkeley.edu/interchange.html

Bloomberg, W.J. 1962. Cytospora Canker of Poplars: Factors Influencing the Development of the Disease. Canadian Journal of Botany 40:1271-1280.

Bloomberg, W.J. 1962. Cytospora Canker of Poplars: The Moisture Relations and Anatomy of the Host. Canadian Journal of Botany 40:1281-1292.

Broberg, Cynthia L., John H. Borden, and Leland M. Humble. 2002. Distribution and abundance of Cryptorhynchus lapathi on Salix spp. in British Columbia. Canadian Journal of Forest Research 32:561-568.

Broberg, Cynthia L., John H. Borden, and Regine Gries. 2005. Olfactory and Feeding Preferences of Cryptorhynchus lapathi L. (Coleoptera: Curculionidae) Among Hybrid Clones and Natural Poplars. Environmental Entomology 34:1606-1613.

Farmer, Robert E., Jr. 1963. Effect of Light Intensity on Growth of Populus tremuloides Cuttings Under Two Temperature Regimes. Ecology 44:409-411.

Faust, Mildred E. 1936. Germination of Populus grandidentata and P. tremuloides with Particular Reference to Oxygen Consumption. Botanical Gazette 97:808-821.

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: http://www.fs.fed.us/database/feis/ [2010, January 21].

Hudson, Shelley, and Michael Carlson. 1998. Propagation of Interior British Columbia Native Plants from Seed. British Columbia Ministry of Forests. Online at http://www.for.gov.bc.ca/hfd/pubs/docs/mr/Mr093/Mr093.pdf

Idaho Native Plant Society. 1999. Native Plants of Northern Idaho for Landscaping and Restoration. INPS White Pine Chapter. Moscow, ID. Online at http://www.idahonativeplants.org/guides/NorthIdahoGuide.aspx

Jacobi, W.R. 2006. Cytospora Canker. Colorado State University Extension Bulletin no. 2.937. Online at http://www.ext.colostate.edu/pubs/garden/02937.html Accessed 1/25/10.

Kepley, J.B. and W.R. Jacobi. 2000. Pathogenicity of Cytospora Fungi on Six Hardwood Species. Journal of Arboriculture 26(6):326-333.

Kufeld, Roland. 1973. Foods Eaten by the Rocky Mountain Elk. Journal of Range Management 26:106-113.

Kruckeberg, Arthur R. 1996. Gardening with Native Plants of the Pacific Northwest. University of Washington Press. Seattle, WA.

McDonough, W. T. 1979. Quaking aspen-seed germination and early seedling growth. USDA Forest Service, Research Paper INT-234. Intermountain Forest and Range Experiment Station, Ogden, UT.

Moss, E.H. 1938. Longevity of Seed and Establishment of Seedlings in Species of Populus. Botanical Gazette 99:529-542.

Perala, D.A. 1990. Populus tremuloides Michx., Quaking Aspen. In: Burns, Russell M., and Barbara H. Honkala (tech. coords.) 1990. Silvics of North America: Vol 2, Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, DC. Online at http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm. Accessed 2/2/09.

Pocewicz, Amy. 2005. Host Plants of Palouse Butterfly Species. 2 page handout to accompany the April 2005 presentation to the Palouse Prairie Foundation.

Rose, Robin, Caryn E.C. Chachulski, and Diane L. Haase. 1998. Propagation of Pacific Northwest Native Plants. Oregon State University Press, Corvallis, OR.

Stubbendieck, James, Stephan L. Hatch, and Charles H. Butterfield. 1997. North American Range Plants. 5th edition. University of Nebraska Press, Lincoln, NE. 501 pp.

USDA NRCS. 2010. The PLANTS Database (http://plants.usda.gov, 25 January 2010). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

University of British Columbia. 2003. British Columbia Flora. University of British Columbia Botanical Garden and Centre for Plant Research. Accessed 9/1/09 online at http://www.bcflora.org/

Wyckoff, Gary W. and John C. Zasada. undated. Populus L. poplar, cottonwood, aspen. In: Bonner, Franklin T., and Rebecca G. Nisley (eds.). Woody Plant Seed Manual. USDA Forest Service. Available online at http://www.nsl.fs.fed.us/wpsm/

Links:
Plant Profile from the USDA PLANTS Database
Species account from the Fire Effects Information System
Species information from the University of Washington Herbarium
Plant Guide from the USDA PLANTS Database