Return to Native Trees of the Southern Rocky Mountains

Their shade is delicious in the long summers, and in winter they yield fuel to the outdoor ovens and little triangular fireplaces. The liquid whisper of their foliage is sweet to hear, and its autumnal hue of lemony gold is very fair against the bald blue of the skies. - Donald Culross Peattie

The Rio Grande cottonwood grows near water, and in places where it can get its roots wet, in the lower valleys, from 4000 to 7000 feet or so in elevation, the lower limit of the Narrowleaf cottonwood, along the Colorado, San Juan, Yampa, White, and Gunnison Rivers; in the southwestern corner of Colorado; and especially near the old Spanish settlements along the Rio Grande in Colorado and New Mexico. It is very similar to the Plains cottonwood except in small details.

These cottonwoods grow 50 to 90 feet high with a thick trunk up to 4 or more feet in diameter. A Rio Grande cottonwood, or possibly a Fremont Cottonwood, growing in Ruby Canyon on the Colorado River at the Utah border was 207 years old when it was measured in 1995, a very old age for a cottonwood, and it was still alive.

The Rio Grande cottonwood ( Populus deltoides var. wislizenii ) is a variety of the Eastern cottonwood. One difference of the Rio Grande cottonwood from the Eastern is that the stalks of the seed capsules are longer than the capsules. It is sometimes called the Valley cottonwood or the Wislizenus cottonwood. The scientific name is for Frederick Aldolphus Wislizenus, a German physician and plant collector who traveled in Colorado in 1839 and in New and Old Mexico in 1846 and 1847. In the Spanish settlements of the southwestern U.S. this cottonwood was known by the name Alamo, and an Alamo tree gave its name to the famous mission of San Antonio, Texas.

Indians ate the raw catkins (flower spikes) of this tree, and made baskets from young cottonwood shoots. The vegas or roof beams of adobe houses are made from the trunks. The foliage is browsed by mule deer and horses, and presumably beavers eat the leaves and use stems for building. Many cottonwood limbs were burned in the campfires of Indians, explorers and ranchmen, and in the cabins of settlers and prospectors of the old west.

Some naturalists think this tree is the same species as the Fremont Cottonwood which is found further west, in Arizona and California. The differences are subtle; both are similar to the Plains cottonwood and there is little doubt that all three can hybridize if they grow close enough for cross-pollination.

The leaf blade is a broad triangle usually 2 to 4 inches long and 2 to 3 inches wide; coarsely toothed with usually fewer than 10 teeth per side -- the Plains cottonwood leaf usually has more than 10 teeth per side -- with a narrow, tapering drawn-out point. Leaf stalks are about two inches long and flattened. The flattened leaf stalks allow the leaves to sway back and forth in even the slightest breeze.

The bark is quite similar to Plains cottonwood bark: on mature trees, the bark is light gray to pale brown, with flat-topped ridges bisected by v-shaped vertical grooves, which can be an inch or more deep.