Scientific Name: Populus fremontii
Description: The Fremont cottonwood is a tree that grows in riparian areas near streams, rivers and wetlands in the American Southwest. It has a broad, open crown and stout, widely spreading branches. When the tree is young the bark, branches and twigs are smooth. As the tree ages the bark becomes deeply furrowed with cracks. Its leaves are shiny, triangular to heart-shaped and light green with white veins and coarse teeth on the margins. The leaves turn golden yellow in the fall.
Cottonwoods are some of the most important wildlife trees in the Western U.S. As one of the major overstory trees in riparian areas of the west, and since riparian areas are some of the most productive wildlife habitat, they are one of the most important plant species to western wildlife. Beaver use cottonwood for making dams and lodges and eat the bark for food. Rabbits, deer, elk and moose feed on shoots and stems. Many insects and the birds and other predators that feed on them thrive in cottonwoods. Raptors often use cottonwoods for nest sites. Once cottonwoods start to die, cavities in them are used by over 40 species of animals for nesting or roosting. Hollowed out trees are used by hibernating bears and sometimes bats. The trees are also important for stabilizing stream banks, producing debris that provides habitat for fish, and providing erosion control and shade.
Size: The Fremont cottonwood can grow to about 70-90 feet in height with a diameter of two to three feet.
Typical Lifespan: Cottonwoods can live for more than 130 years.
U.S. Habitat: They are most abundant in areas near water. Cottonwoods dominate the riparian forests of lower terrace deposits and stabilized gravel bars.
Range: Fremont cottonwoods are distributed throughout the Southwestern United States, from California eastward to Nevada, Utah, Arizona, New Mexico, and Texas, and southward into Mexico
Life History and Reproduction: The Fremont cottonwood is a very fast growing tree. It requires a moist soil setting for its seeds to germinate. It is dioecious, meaning that it can have either male or female reproductive parts. Male and female reproductive parts are held in catkins. The flower is yellow-green in color and appears in early spring. The fruit it produces is a light brown, small, egg-shaped capsule which splits three ways to disseminate many small seeds covered with cotton-like fluff for wind dispersal.
Fun Fact: During the early days of exploration of the western United States, cottonwood groves were used as an indicator of water, as they grow only on wet soil.
Conservation Status: Because of the land use in arid watersheds, the cottonwood riparian forests have been significantly decreased or destroyed. Livestock grazing has also been identified as a leading factor contributing to the degradation of riparian habitats in the western United States. Also, because of ground-water pumping, it lowers local and regional water tables and reduces stream flow, which can eliminate or weaken riparian vegetation. Unfortunately, there are no released cultivars of the Fremont cottonwood. There are however, contained Fremont cottonwood samplings which are available from most nurseries in the areas where adapted.
Native Plant Database, Lady Bird Johnson Wildflower Center
USDA Natural Resources Conservation Service
U.S. Forest Service Fire Effects Information System
vTree, Virginia Tech Forest Resources and Environmental Conservation
What Good is a Cottonwood Tree? In Forest Stewardship Notes, Washington State University Extension