Kingdom: Plantae

Phylum: Magnoliophyta -- flowering plants

Class: Magnoliopsida -- dicotyledons

Order: Salicales

Family: Salicaceae -- willow

Infraspecific taxa: none recognized under P. trichocarpa, but this taxon is now considered a ssp. of P. balsamifera

Common Name: black cottonwood

Species Code: POBAT, POTR15

Origin: Native to streamsides and floodplains over much of western North America from Alaska to California and east to Utah, Wyoming, and Alberta.

Rare: no

Form: tree to 50 meters; younger bark smooth, brown, becoming rough, furrowed and gray with age; buds large, very resinous; twigs glabrous or sparsely hairy.

Mature height: to 165 feet

Duration: perennial

Longevity: medium lifespan

Habitat Type: riparian

Wetland Indicator Status: FAC

Leaves: alternate; petiole often with a pair of glands near the blade and channeled on the upper surface; blade generally glabrous, green above, pale underneath, leaves often of two forms, narrowly to broadly ovate or lanceolate, rounded or cordate at the base, 5-15 cm long and 3-9 cm wide, acute or acuminate, margins crenulate.

Flowers: borne in a pendent catkin (ament), precocious; perianth lacking, each flower subtended by a scale; staminate catkins 2-3 cm long, soon deciduous; pistillate catkins 8-20 cm long.

Flower color: inconspicuous

Bloom: April

Fruit: capsule, broadly ovoid; seeds small, lacking endosperm, coma consisting of long white hairs.

Characteristics:
Populus balsamifera ssp. trichocarpa is the currently accepted name.
P. hastata in St. John 1963.
2n=38 (Baldwin et al 2004).
Diploids only are known.
Wind pollinated.
Plants are dioecious.
Flowers borne in precocious catkins.
Fruit is a capsule.
Seeds are dispersed by wind and water.
Bald eagles and great blue herons nest in the trees (Matthews 1988).
An important browse plant for Rocky Mountain elk in winter (Kufeld 1973).
Provides habitat, cover, and food for a number of species, including browsers, beaver, and cavity users.
P. trichocarpa shades stream water and thus improves fish habitat by lowering water temperatures.
The cambium layer and sap were consumed by Native Americans. They used the buds and bud resin medicinally. The wood and bark was also used (Moerman 2003).
Wood is used for particle board, lumber, pulp, veneer, and plywood.
The poplar and willow borer, Cryptorhynchus lapathi, an introduced weevil from Eurasia, attacks many species of poplar and willow. Larva bore into the stems and weaken them, causing breakage or death (Broberg et al 2002, Broberg et al 2005).
Populus species may be hosts for the larva of the persius duskywing butterfly (Erynnis persius), the mourning cloak (Nymphalis antipoa), the western tiger swallowtail (Papilo rutulus), and Lorquin’s admiral, (Limentis lorquini) (Pocewicz 2005).

Comments: 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.

Sun requirement: full sun

Soil moisture: mesic

Precipitation: 20-125 inches (USDA NRCS PLANTS Database 2010).

Fire: Top-killed by most fires, but often resprouts from roots and stumps. Seedling recruitment is enhanced by fires which clear the litter to mineral soil. Habitat is less susceptible to fire than the surrounding upland areas (Steinberg 2001).

Sowing time: not recommended

Transplant time: spring or fall

Stratification: none required

Seed yield: high

Seed harvest: difficult

Seed first harvest: no information available

Seed cleaning: medium difficulty

Planting duration: long

Seed shatter: high

Seed size: small

Seed harvest date: spring

Seed comments: Seed is windborne.

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

Keywords: native perennial upland wetland tree

Propagation:
3 protocols in the Native Plant Network
Glacier National Park, Montana
Forest Service, Southern Research Station, Moscow, Idaho
City Of Portland, Oregon

Other Propagation Information:
Can be propagated from seed, but a moist seedbed is essential. Sow immediately after collecting. Dormant stem cuttings taken in November thru March are the best method. (Rose et al 1998).
Propagate by seeds, cuttings, or layering. Seeds and substrate must be kept moist (Kruckeberg 1996).
Younger wood roots better than older wood. Cuttings root at the capillary fringe but not in the saturated soil zone (Stannard & Guenther 1999).
Reproduction in the wild is mainly by seed (Borman & Larson 2002).
Reproduces sexually by seed. Sometimes reproduces vegetatively from broken branches and twigs. Fresh seed germinates at high rates, but deteriorates quickly, often in 2-4 weeks, if not on a suitable germination substrate.

Notes: Seed grown plants are preferable to clonal material in restoration plantings because seed grown plants provide a broader gene base.

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 2/5/10 online at http://ucjeps.berkeley.edu/interchange.html

Bloomberg, W.J. 1962. Cytospora Canker of Populars: 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.

Boes, Teresa K., and Steven H. Strauss. 1994. Floral Phenology and Morphology of Black Cottonwood, Populus trichocarpa (Salicaceae). American journal of Botany 81:562-567.

Borman, Michael, and Larry Larson. 2002. Cottonwood Establishment, Survival, and Stand Characteristics. Oregon State University Extension Service publication EM 8800. Corvallis, OR.

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.

Critchfield, William B. 1960. Leaf Dimorphism in Populus trichocarpa. American Journal of Botany 47:699-711.

DeBell, Dean S. 1990. Populus trichocarpa Torr. & Gray, Black Cottonwood. In: Burns, Russell M., and Barbara H. Honkala (tech. coords.) 1990. Silvics of North America: Vol 1. Conifers, and 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 2/2/10.

Hitchcock, C. Leo, Arthur Cronquist, Marion Ownbey, and J.W. Thompson. 1969. Vascular Plants of the Pacific Northwest. University of Washington Press. Seattle, WA. 5 vol.

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.

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.

Mathews, Daniel. 1988. Cascade-Olympic Natural History: A Trailside Reference. Raven Books. Portland, OR.

Moerman, Dan. 2003. Native American Ethnobotany: a Database of Foods, Drugs, Dyes and Fibers of Native American Peoples, Derived from Plants. University of Michigan-Dearborn. Online at http://herb.umd.umich.edu/ Accessed 1/3/07.

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.

Stannard, Mark, and Haley Guenther. 1999. Rooting Characteristics of Black Cottonwood and Pacific Willow. Plant Materials Tech Note 29. USDA, NRCS. Spokane, WA.

Steinberg, Peter D. 2001. Populus balsamifera subsp. trichocarpa. 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, February 5]

St. John, Harold. 1963. Flora of Southeastern Washington and of Adjacent Idaho. 3rd edition. Outdoor Pictures. Escondido, CA.

USDA NRCS. 2010. The PLANTS Database (http://plants.usda.gov, 5 February 2010). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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/