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| ## black cottonwood {#black-cottonwood .Title-Header}                 |
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| *Populus balsamifera* L. ssp. *trichocarpa* (Torr. & Gray ex Hook.)   |
| Brayshaw                                                              |
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| Plant Symbol = POBAT                                                  |
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Contributed by: USDA NRCS National Plant Data Center & the Biota of
North America Program

## Alternate names

Common black cottonwood, balsam cottonwood, western balsam poplar,
California poplar; *Populus trichocarpa* Torr. & Gray

## Uses

*Industry*: Black cottonwood is a commercially valuable tree. Primary
products include particle board, plywood, veneer, and lumber. The wood
is light colored and light in weight; it is diffuse-porous (indistinct
growth rings), with a fine, even texture. The light weight, good nailing
characteristics, and light color of the lumber are ideal for manufacture
of pallets, boxes, and crates. It also is used in concealed parts of
furniture. The fibers are short and fine, making the wood useful in
production of pulp for tissues and high-grade book and magazine paper.

Poplar hybrids, particularly *Populus trichocarpa* x *P. deltoides*, are
currently the subject of much research into their genetics and
physiology. These are extremely fast-growing and biomass-productive when
grown as short-rotation coppice or single stems. On good sites, hybrid
poplars grow faster than any other northern temperate region tree and
hybrids are usually more widely adaptable than the parents. They are
easily propagated from stem cuttings, but because of quick re-sprouting,
replanting after harvesting may be unnecessary, especially for short
harvest cycles. These trees have great potential for conservation and
ornamental plantings, paper, and lumber and plywood. The wood is similar
to that of native black cottonwood, and branches and tops left from pulp
harvests can be converted to pelletized fuel for use in power stations
and home heaters. ![](media/image2.jpeg){width="2.9805555555555556in"
height="2.245833333333333in"}

*Wildlife*: Black cottonwood provides food and cover for a variety of
wildlife species, including deer, elk, and beaver. Large birds use the
crowns for nesting sites and various animals rely on the trunk cavities,
which commonly result from heart rot in most stands nearing maturity.
The rotten trunks of black cottonwood provide an important wildlife
habitat otherwise scarce, especially of the Cascades.

*Ethnobotanic*: Disinfectant properties of resin from buds were
discovered by Native Americans, who used the resin to treat sore
throats, coughs, lung pain, and rheumatism. It is still used in some
modern natural health ointments. Soap was produced from the inner bark.
The wood was used to make friction fire sets.

*Conservation*: Black cottonwood is a very fast-growing and potentially
large tree, easy to establish, and useful for shade and ornament. Black
cottonwood also has been planted as windbreaks and shelterbelts and it
is commonly used for screening along motorways in Europe. The aggressive
root systems of black cottonwood are effective soil stabilizers and make
the species useful in restoration of riparian areas, where it also
provides protection for the aquatic environment, especially in helping
to maintain low water temperatures through shading. The high nitrate
uptake and extensive rooting of these trees make them useful for buffer
or \"filter\" planting along streams in agricultural areas.

## Status

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status, such as state noxious status
and wetland indicator values.

## Description 

*General*: Willow Family (Salicaceae). These are native trees up to
30-60 m tall, usually with a straight, branch-free trunk for more than
half its length, forming a broad, open crown in open sites; bark gray to
gray-brown on mature trees, deeply furrowed into flat ridges on older
portions. The leaves are deciduous, simple, alternate, ovate-lanceolate
to deltate but variable in size and shape on same tree, rounded or
cordate at base, 7-12 cm long, 3.5-7.5 cm wide, hairless or nearly so,
the margins finely toothed, dark green above and slightly paler beneath,
commonly with whitish or brownish resin blotches, turning yellow in
autumn, the petioles round, 3-4 mm long. Flowers male (staminate) and
female (pistillate), on separate trees (the species dioecious), each
type borne in pendent catkins, the female elongating to 6-8 cm long.
Fruits nearly globular capsules 3-4 mm long, splitting to release the
seeds; seeds ca.2 mm long, each with a tuft of long, white, silky hairs
("cotton"), easily blown by the wind. The common name is in reference to
the dark colored bark.

Black cottonwood is the largest American poplar and the largest hardwood
tree in western North America.

*Variation within the species:* black cottonwood is most commonly and
widely known as the distinct species *Populus trichocarpa* but is
sometimes treated as *Populus balsamifera* var. *trichocarpa*, the
western North American segment of the broader species *P. balsamifera*
(Brayshaw 1965, 1976). Black cottonwood and balsam cottonwood have
similar appearances, biological features, and ecology, and they
hybridize and introgress where their ranges overlap. Still, they have
essentially separate geographic ranges, and, like various other species
of *Populus* that are separated by relatively small differences, black
cottonwood and balsam poplar differ in a number of technical features,
as partly summarized here.

1\. Petioles 7-10 cm long, often with glands at base; terminal bud with
5 scales; staminate catkins 7-10 cm long; mature pistillate catkins
10-13 cm long; fruits ovoid, 6-7 mm long, splitting into 2 parts.
\...\...\.... *P. balsamifera*

1\. Petioles 3-4 cm long, without basal glands; terminal bud with 6-7
scales; staminate catkins 4-5 cm long; mature pistillate catkins 12-15
cm long; fruits nearly globular, 3-4 mm long, splitting into 3 parts.
\...\..... *P. trichocarpa*

Brayshaw has recognized two varieties within "subsp. *trichocarpa*:"
Var. *trichocarpa* (in central and coastal British Columbia and
southward) and Var. *hastata* (Dode) Brayshaw (mainly in the Rocky
Mountain region and central British Columbia)

Natural hybrids occur between black cottonwood and other species:
narrowleaf cottonwood (*P. angustifolia*), eastern cottonwood (*P.
deltoides*), Fremont's cottonwood (*P. fremontii*), and rarely even
aspen (*P. tremuloides*).

## Distribution

The range of black cottonwood extends from Alaska, including various
islands, through coastal regions of western Canada (Yukon, British
Columbia, and Alberta) into the northwestern US (Washington, Oregon,
Montana, Idaho, and Nevada; rare in North Dakota, Wyoming, Utah, and
California) and as far south as Baja California Norte. For current
distribution, please consult the Plant Profile page for this species on
the PLANTS Web site.

## Adaptation 

Black cottonwood grows on alluvial sites, riparian habitats, and moist
woods on mountain slopes, at elevations of 0--2100(--2750) meters. It
often forms extensive stands on bottomlands of major streams and rivers
at low elevations along the Pacific Coast, west of the Cascade Range. In
eastern Washington and other dry areas, it is restricted to protected
valleys and canyon bottoms, along streambanks, and edges of ponds and
meadows. It grows on a variety of soils from moist silts, gravels, and
sands to rich humus, loams, and occasionally clays.

Black cottonwood is a pioneer species that grows best in full sunlight
and commonly establishes on recently disturbed alluvium. Seeds are
numerous and widely dispersed because of their cottony tufts, enabling
the species to colonize even burn sites, if conditions for establishment
are met. Seral communities dominated or codominated by cottonwood are
maintained by periodic flooding or other types of soil disturbance.
Black cottonwood has low drought tolerance; it is flood-tolerant but
cannot tolerate brackish water or stagnant pools.

Flowering occurs in late March to May (-June), just before or during
leaf emergence and fruiting occurs in late May to early or mid-July.

## Establishment

Black cottonwood begins producing seed at about 8-10 years -- abundant
seed is usually produced every year. Seeds under natural conditions are
short-lived, usually for less than a month. Seed will readily germinate
on a variety of favorable sites, particularly where mineral soil has
been exposed or new soil deposited. High germination rates and seedling
survival depend on continuously moist conditions, such as in fresh
alluvium, during the first month.

Maximum height and size are usually reached in 60-75 years although some
may continue to grow well past that. Maximum age is at least 200 years.

Black cottonwood sprouts readily from the stump and roots as well as
from branches and logs that are left after logging. Small shoots with
green leaves abscise naturally and either root where they fall or are
water-transported some distance before they root.

## Management

In urban sites, the aggressive root systems of black cottonwood can
invade and damage drainage systems and also may heavily draw available
moisture from gardens and building foundations, especially in clay soil.
Root suckers also may be considered a maintenance problem, and the
profuse production of cottony seed from female plants can be a minor
nuisance. The shallow root system of black cottonwood, especially on wet
soils, make the species susceptible to damage from ice storms, heavy
snow, and wind. Unseasonably early or late frosts may damage saplings,
but in dormancy, it is one of the most frost-resistant trees in the
northwestern USA.

Black cottonwood is susceptible to fire damage because of its thin bark
and shallow root system. Seedlings and saplings are usually killed by
fire of any intensity, and all trees may killed by high-intensity fire.
Even relatively cool fires may wound older trees and open the way to
heartwood decay. Repeated fire at short intervals may permanently
exclude black cottonwood. Even so, post-fire regeneration may be
effective and rapid in black cottonwood. Thickened bark on lower
portions of the trunk after 10-20 years affords better fire protection,
and moist soil contributes to the survival of underground parts. Trees
can quickly sprout from the stump and roots following top-kill or damage
by fire. Abundant production of seeds and their wide dispersal enable
black cottonwood to rapidly colonize large areas of moist soil after
burns, which provide ideal conditions of maximum light and bare mineral
soil.

Collect seeds for propagation as capsules begin to open (late May to mid
July). Place in paper bags and allow them to finish opening in warm
area. They need to be sown within a few days of ripening; otherwise they
may be kept viable for up to a year by drying and storing cold in an
air-tight container. In a cold frame, sow on the surface or lightly
cover the seeds. Plant into permanent positions either in late summer or
the following spring, depending on growth of the young plants.

Cuttings of twigs of the current season\'s growth, 20-45 cm long and 1-3
cm diameter, taken during the dormant season and with healthy axillary
buds, can be placed in a sheltered outdoor bed or directly into
permanent positions. Plant with one bud above the surface. Cuttings
grown in a mist-propagator also root easily. Nursery- or container-grown
seedlings and rooted cuttings establish easily and grow rapidly on moist
well-drained soils in full sun. Live stakes should be 3.5 cm diameter
and 1.2 m long, stuck directly into ground on-site.

## Cultivars, Improved and Selected Materials (and area of origin)

Contact your local Natural Resources Conservation Service (formerly Soil
Conservation Service) office for more information. Look in the phone
book under "United States Government." The Natural Resources
Conservation Service will be listed under the subheading "Department of
Agriculture."

## References

Authors 2000. *Hybrid poplar research program*. Dept. of Energy,
Biofuels Program, Washington State University, Puyallap, Washington.
SEP00. \<http://www.puyallup.wsu.edu/poplar/hybridpoplar/poplar.htm\>

Brayshaw, T.C. 1965. *The status of the black cottonwood (Populus
trichocarpa Torrey and Gray)*. Canad. Field-Naturalist 79:91-95.

Brayshaw, T.C. 1976. *Catkin bearing plants of British Columbia*. Occas.
Pap. No. 18. The British Columbia Provincial Museum, Victoria, British
Columbia, Canada.

DeBell, D.S. 1990. *Populus trichocarpa Torr. & Gray, black cottonwood*.
Pp. 60-69, IN: R.M. Burns and B.H. Honkala (tech. coords.). *Silvics of
North America*. *Volume 2.* *Hardwoods*. USDA, Forest Service Agric.
Handbook 654, Washington, D.C. SEP00.
\<http://willow.ncfes.umn.edu/silvics_manual/volume_2/populus/trichocarpa.htm\>

DeBell, D.S., C.A. Harrington, G.W. Clendenen, M.A. Radwan, & J.C.
Zasada 1997. *Increasing the productivity of short-rotation Populus
plantations*. Final Report, USDA, Forest Service, Pacific Northwest
Research Station, Olympia, Washington.
\<http://bioenergy.ornl.gov/reports/debell/contents.html\> Accessed
September 2000.

Dickmann, D.I. & K.W. Stuart 1983. *The culture of poplars in eastern
North America*. Michigan State University, Department of Forestry, East
Lansing, Michigan.

Eckenwalder, J.E. 1977. *North American cottonwoods Populus (Salicaceae)
of sections Abasco and Aigeros*. J. Arnold Arb. 58:193-207.

Galloway, G., & J. Worrall 1979. *Cladoptosis: A reproductive strategy
in black cottonwood?* Canad. J.

Forest Res. 9:122-125.

Holifield, J.L. 1990. *Populus trichocarpa*. IN: W.C. Fischer
(compiler). *The fire effects information system* \[Data base\]. USDA,
Forest Service, Intermountain Research Station, Intermountain Fire
Sciences Laboratory, Missoula, MT.
\<http://fire.org/feis/plants/tree/poptri/Final Report\> Accessed
September 2000.

Johnson, J.D., T.M. Hinckley, & H.D. Bradshaw 2000. *Disease resistance,
its physiology and genetics of short-rotation black cottonwood*. Dept.
of Energy, Biofuels Program, Washington State University, Puyallap,
Washington. SEP00.
\<http://www.puyallup.wsu.edu/poplar/rschprojects/rsch1.htm\>

## Prepared By

*Guy Nesom*

Formerly BONAP, North Carolina Botanical Garden, University of North
Carolina, Chapel Hill, North Carolina

## Species Coordinator

*James Henson*

USDA, NRCS, National Plant Data Center, Baton Rouge, Louisiana

Edited: 19jun02 jsp; 29may03 ahv; 060808 jsp

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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