Narrowleaf cottonwood in summer

Narrowleaf Cottonwood Trees

The Narrowleaf Cottonwood tree is found in the Denver metro area and also can be seen along the river and creek banks up into the mountains.  It is found along stream and river beds and floodplains where it can get the regular moisture and periodic flooding that it needs.

If you ever see a tree with the furrowed bark of a Plains Cottonwood tree at the base and the smooth white bark of an Aspen tree at the top, then chances are good that you have spotted a Narrowleaf Cottonwood tree. This tree can reach a height of up to 60 feet with branches spreading out to 40 feet. 

The leaves are about 5-9 cm long and 1-2 cm wide, giving this tree its name.  The petiole, which is the stem attaching the leaf to the twig, is less than 1/3 the length of the leaf. The bark of the Narrowleaf Cottonwood is smooth on the upper parts of the tree and furrowed into broad, flat ridges on lower portions.

Scientific Name and Plant Family Information

The Scientific name is Populus angustifolia. Populus refers to the Latin word for people, which relates back to Roman plazas being planted with Poplars. Angustifolia means narrow leaves.

It is in the plant family Salicaceae (Willow), which also has aspen trees and poplars along with willow shrubs and trees.  A couple of interesting things about this plant family are that the plants have male and female flowers on different plants (dioecious) and the bark has methyl salicylate, from which aspirin was originally derived.

Narrowleaf cottonwood leaves
Narrowleaf Cottonwood leaves

Through the Seasons

In the spring, the female trees produce small tufts of fluffy white fibers like cotton which contain the seeds and are carried along in the wind. In the fall, the leaves turn a brilliant gold like its relative, the Aspen tree.  In the winter, these trees can be recognized by the bark being gray and furrowed at the base and white and smooth like Aspen trees at the top.

Also, Narrowleaf Cottonwood trees send up a lot of suckers for new trees and those can be seen around the base of the tree. Due to the many suckers it sends up, this tree is frequently planted along stream banks for soil stabilization and for blocking unsightly views.

Narrowleaf Cottonwood in winter
Narrowleaf Cottonwood tree in winter

Native or Non-Native?

The Narrowleaf Cottonwood tree is native to this area and up into the mountains, growing along streams and in floodplains.  It can be found throughout much of Colorado at elevations from 5,000 to 10,500 feet.

Where to find in Willow Spring Open Space

Narrowleaf Cottonwood trees can be found along the path heading up into the Homestead neighborhood on the southwest side of the open space.

Did You Know?

Narrowleaf Cottonwood trees provide habitat cover and food for many birds, squirrels, beavers and even bears, white-tailed deer and moose further up into the mountains.

References and Further Reading