Populus fremontii

Fremont cottonwood


The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Magnoliophyta (flowering plants). Class - Magnoliopsida (dicotyledons). Subclass - Dilleniidae. Order - Salicales. Family - Salicaceae (willow family). Genus - Populus L. (cottonwood). Species - Populus fremontii S. Watson (fremont cottonwood).

Ecology: Fremont cottonwood is a native, deciduous hardwood tree that ranges from 6-34 m in height and has a broad, rounded or cylindrical crown. The trunk diameter at breast height ranges from 0.5-3.9 m.The bark is smooth on the trunk, twigs, and branches of young trees, but trunk bark becomes deeply furrowed at maturity. Fremont cottonwood is inundation and siltation tolerant.

Fremont cottonwood is a shade-intolerant pioneer that typically establishes on freshly exposed alluvium, sand or gravel bars, streambanks, or other floodplain sites following winter/spring floods. Communities dominated or codominated by Fremont cottonwood and other cottonwoods (Populus spp.) are naturally maintained by periodic winter and spring floods. Dams and reservoir systems that change the natural timing and volume of water flow reduce the recruitment and vigor of Fremont cottonwood stands. In the absence of periodic flooding, succession proceeds, and the cottonwoods are eventually replaced by more shade-tolerant species (for example, western honey mesquite).

Fremont cottonwood's rapid early growth makes it well suited for revegetating riparian sites. It has been successfully planted in many riparian rehabilitation projects and is recommended for revegetating areas in the Southwest where invasive saltcedar has been removed. Fremont cottonwood, along with willows and other native plants, has also been used to restore, enhance, or create bird habitat in riparian areas...Fremont cottonwoods and other components of riparian streamside stands are important in erosion control and fisheries production; they stabilize banks and provide for thermal cover and debris recruitment. If possible, buffer strips of these woodlands should be maintained upland from streams, rivers, lakes, and ponds.


A fast-growing riparian tree, Fremont’s cottonwood has been known to grow 30 ft. in one year. Its ultimate height is up to 90 ft. Tree with broad, flattened, open crown of large, widely spreading branches. The crown is broad and open with stout branches. Bark is whitish and roughly cracked. The triangular, deciduous leaves are bright green turning yellow in fall.

This species, including varieties, is the common cottonwood at low altitudes along the Rio Grande and Colorado River and in the rest of the Southwest, as well as in California. Fremont Cottonwood grows only on wet soil and is an indicator of permanent water and shade. Easily propagated from cuttings, it is extensively planted in its range along irrigation ditches, and although it grows rapidly, it is short-lived. To this day, Hopi Indians of the Southwest carve cottonwood roots into kachina dolls, the representations of supernatural beings, that have become valuable collectors items. Horses gnaw the sweetish bark of this species; beavers also feed on the bark and build dams with the branches. Greenish clumps of parasitic mistletoes are often scattered on the branches.


Fremont cottonwood communities are declining as a result of human activities. A 1914 survey along the Gila River of Arizona showed 641 hectares - 33% of the survey area - was occupied by Fremont and other cottonwoods. Fremont cottonwood was the most widespread riparian community of the Southwest. A 1944 survey of the same area showed on 65 hectares so occupied; by 1964, Fremont cottonwood was no longer a cover type: only a few scattered trees remained.

Cattle grazing prevents successful regeneration of Fremont cottonwood seedlings, and exclusion of grazing in Fremont cottonwood riparian zones has been recommended.

Fire effects: Fremont cottonwoods are not fire dependent. Mature Fremont cottonwood trees are top-killed by moderate fire. The cambium layer is damaged by even low-severity surface fire. Most cottonwoods (Populus spp.) readily coppice following an injury such as fire; Fremont cottonwood sprouts primarily from the bole. This ability presumably depends on fire severity. Fremont cottonwood also sprouts from roots. Sprouting ability of cottonwood species is reported to decline after 25 years of age.


Fremont cottonwood is dioecious, with small (approximately 1 mm in length), fragile seeds. The catkins range from 3.75-8.26 cm for the staminate and 10.16-12.70 cm for the pistillate.

Seed Production - Fremont cottonwood reaches reproductive maturity between 5 and 10 years of age. Flowers are produced early in the spring and are entirely wind pollinated. Large crops of seed are produced in the spring; the seeds have a cottony tuft of trichomes that enables them to float long distances in the wind and on water. Seeds may not be fully viable when dispersed. Seeds typically germinate within 24 to 48 hours on suitable seedbeds, but seeds may remain viable for 1 to 5 weeks after dispersal. Viability is lost if a suitable microsite is not found within 2 or 3 days of seed becoming wet.

Seedling Establishment - Suitable recruitment sites are created by the floodwaters of spring run-off. Seeds germinate almost exclusively on the freshly deposited, exposed alluvium left by receding floodwaters. The availability of this type of moist, exposed habitat during and 6 to 8 weeks after seed dispersal is crucial because of the limited period of seed viability. Abandoned secondary and tertiary stream channels are valuable recruitment sites because subsurface water is available and some protection from scouring is provided.

Vegetative regeneration - Cottonwood species (Populus spp.) reproduce vegetatively by sprouting from stumps and root crowns, by forming suckers (adventitious shoots on roots), and from stem cuttings. Root suckering has been observed to be the predominant method of regeneration of Fremont cottonwood in some areas in Utah. Root or bole sprouting often occurs after some injury (uprooting, broken branches). Sprouting from lateral buds on stems occurs when there is contact with moist alluvial soil.

Species Distribution


USDA Plant Database
USDA, NRCS. 2016. The PLANTS Database (http://plants.usda.gov, 4 February 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America
Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  19+ vols.  New York and Oxford.

Intermountain Herbarium
Consortium of Intermountain Herbaria. 2016. http//:intermountainbiota.org/portal/index.php. Accessed on February 04.

Jepson Manual
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA. $131.95, hardcover; 1600 pages. ISBN-13: 978-0520253124.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97.
Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.