Site characteristics

Species characteristics (life history)

• Silver maple
• Red maple
• American elm
• Black ash
• Green ash
• Black willow
• Eastern cottonwood
• Other species

Natural and human disturbance

Stand characteristics

Eastern cottonwood

Figure 25. The native range of eastern cottonwood (Burns and Honkala 1990). Figure 26. Eastern cottonwood bark. Figure 27. Eastern cottonwood leaves. Figure 28. Eastern cottonwood catkins.

Eastern cottonwood (Populus deltoides) is common throughout much of the eastern United States and adjacent Canada (Figure 25). It grows on a variety of soil types but prefers moist, well-drained sands or silts along river bottoms. It is often establishes in nearly pure pockets between levees and the main watercourse. Eastern cottonwood is very intolerant to shade, in fact only black willow is less tolerant among the species commonly found within bottomland hardwood forests. It is a fast-growing, tall tree. Young tree develop smooth yellowish-green bark which becomes dark and furrowed with age (Figure 26). It is a shallow rooted species with most roots found in the uppermost layers of the soil. Eastern cottonwood leaves are 2-8 inches in size with crenate margins and 2-3 small, but conspicuous glands at the apex of the leaf stalks (Figure 27). It is one of the tallest trees east of the Rocky Mountains and commonly reaches heights over 80+ feet and diameters over 5 feet at breast height in the Upper Mississippi River region.

Eastern cottonwood is dioecious, meaning male and female flowers are borne on separate trees. Male buds develop earlier in the spring than female buds and are generally much larger. Flowering occurs early in the spring (April or May), well before leaf expansion. Male flowers tend to bloom a few days earlier than female buds and flowering, in general, may vary by as much as a month in some stands. Seeds develop in capsules on short stalks on catkins (Figure 28). Seed production usually starts around age 5 to 10 and fecundity increases with age until maturity. Eastern cottonwood is a prolific seeder and produces large seed crops annually. Seed dispersal occurs approximately 1-2 months after flowering in the northern part of its range and continues for a well over a month. Seeds are primarily dispersed via wind and water. Seed viability is relatively poor as seeds must reach moist seedbeds or be immersed in water to stay viable and germinate.

Germination under the right conditions can exceed 90 percent. Seedlings are very susceptible to the elements and fungi during early development and growth tends to be slow initially and then rapid after the root system has established. Regeneration success is largely tied to soil moisture and sunlight. If either are lacking seed germination and subsequent growth are highly unlikely.

Eastern cottonwood maintains its fast growing habit throughout much of its life, although early growth in controlled environments is on par with some of the fastest growing species in the world. It is the most shade intolerant species in bottomland hardwood forests, next to black willow. The two species often compete in environments where high light conditions exist and water levels fluctuate. Black willow is more tolerant to flooding than eastern cottonwood so in open areas that are flooded for long periods of time willow will outcompete eastern cottonwood. On slightly higher sites where water levels are more stable and the light environment remains high, eastern cottonwood often out competes black willow. Both species often grow in nearly pure stands and are replaced by longer lived, more tolerant species. Eastern cottonwood also grows with a variety of other bottomland species including black ash, American elm, red maple, river birch, silver maple, and to a lesser extent, hackberry, sugarberry, and green ash.

For information on the specific insects and pathogens affecting the health and productivity of eastern cottonwood, see the Specific pest problemssection within the Forest Health tab.

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Burns, Russell M., and Barbara H. Honkala, tech. coords. 1990. Silvics of North America: 1. Conifers; 2. Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, DC. vol.2, 877 p.