Feature Tree – July 2006
Plains Cottonwood
(click here for Tree of the Month archives)

Plains Cottonwood, Populus sargentii or Populus deltoides ssp. monilifera (Salicaceae family)

Habit:  Large-maturing, fast growing.  Typically has a broad, irregularly rounded canopy with coarse, spreading branches.  Some recent cultivars selected for more upright growth habit.  Mature height will be typically 60-80’ with a crown spread approximately 50-60’.

Hardiness:  Zone 3 to 9 up to approximately 7,000’ in elevation.

Leaves:  Rich green deciduous leaves have a wide triangular shape, are alternate, simple, 3 to 6 inches long, with serrate margins.  Golden yellow in fall.       

Twigs:   The twigs are stout, yellowish brown and smooth with a stellate, or star-shaped, pith. The terminal buds are long and resinous.      

Bark:  Smooth grayish brown bark becomes deeply grooved and dark gray as it ages.    

Flowers:   Flowers occur in the spring before the leaves appear, they are dioecious in hanging catkins, meaning both male and female trees occur. 

Fruit:   Fruits of the female tree give this tree its bad reputation as a “cotton producer” and are 1/4 inch long, 3 or 4 valved capsules that can disperse large amounts of cottony seeds.  Avoid this problem by selecting male trees sold in nurseries and garden centers. 

Landscape Value:  Give this native to the Great Plains plenty of above and below ground space to grow.  Unlike many cottonwoods, the Plains Cottonwood grows tall and stately and its roots rarely produce suckers in the yard.  Only males of the species are sold in nurseries, thus cotton production is not an issue.  One of the cultivated male varieties, “Straight Plains” or ‘Jeronimus’ cottonwood keeps a straight main leader, is tolerant of many soil types and conditions, and can make a nice shade tree in landscapes that provide enough room for this tree to mature.  The largest known Plains Cottonwood tree is more than 300 years old, 36 feet around and 105 feet tall. It is located about a mile from Hygiene, Colorado on closed property maintained by Boulder County Parks and Open Space.  Cottonwood is the State tree of Wyoming, Nebraska and Kansas. 

Diseases/Insects:  Cottonwood trees in general can host many different insect and disease problems, can sucker sprout profusely, the weak wood often breaks apart in storms and can be susceptible to considerable decay making many selections a poor choice for the landscape.  The native Plains Cottonwood, however, shows resistance to many of these problems and the ‘Jeronimus’ selection in particular can be a relatively maintenance-free choice in terms of insect and disease problems.  

Information and Photo Sources: 

            Cheyenne, Wyoming Botanic Gardens (http://www.botanic.org/Cottonwoods.pdf) 

Northern State University and the South Dakota Division of Forestry (http://www.northern.edu/natsource/TREESA1/Easter1.htm) 

City of Boulder Open Space (http://www.bouldercolorado.gov/index.php?option=com_content&task=view&id=3401&Itemid=1016) 

            Keith Wood, Colorado State Forest Service