Eastern cottonwood (Populus deltoides) trees have long been vilified by people suffering from seasonal allergies, but the cottony seeds are bearing the blame for a problem they’ve got little to do with. Seasonal allergies are caused by the body’s immune system reacting to inhaled plant pollen, not seeds. It just so happens that cottonwood trees go to seed at the same time many other plants are producing pollen—especially turf grasses. Those itchy eyes and sneezes are much more likely to be caused by highly-allergenic Kentucky bluegrass pollen than anything cottonwoods produce.
It’s true that cottonwoods are not ideal for our urban spaces. They do have aggressive roots, they do have weaker wood more susceptible to failure, and they do produce a huge number of fluffy seeds during the early summer. However, these same attributes that earn them a bad reputation in our built environment make cottonwoods a keystone species in riparian habitats around wetlands and streams. Those same aggressive roots help stabilize streambanks and control erosion in nature. Falling branches may re-route waterways and create new habitat. The abundant seeds are eaten by some waterfowl and ensure the next generation of cottonwoods can provide the same benefits to the area. This is in addition to the habitat and forage opportunities that many large trees provide, such as wildlife feeding on leaves, bark, and buds and nesting sites in the canopy or in trunk cavities.
As with all trees, there are situations in which cottonwoods are an inappropriate planting choice. They shouldn’t be planted three feet from a home’s foundation and sewer line, for example. Though, in the right environment sufficiently far from any buildings or infrastructure, cottonwood trees can thrive and provide all the benefits nature intended. Read on to learn more about one of Michigan’s tallest native tree species.
• Native range: Eastern cottonwoods are native to Michigan
• Size: Cottonwoods can grow to 80 – 100 feet tall with a crown spread of 50 – 70 feet at maturity.
• Life cycle: Cottonwoods have an extremely fast growth rate and an expected lifespan of about 70 years in good conditions.
• Fall color: Yellow. • Flower and fruit: Cottonwoods produce small, inconspicuous flowers and fluffy seeds dispersed by the wind.
• Preferred conditions: Cottonwoods thrive in full sun and wet sites, but also tolerate clay-dense soil and occasional drought.
• Wildlife benefits: The tree is not good at compartmentalizing decay, so it frequently hosts cavity-nesting birds and mammals in decayed portions of its trunk. Its roots also stabilize streambanks to preserve vital riparian habitat.
• Other uses: Because cottonwoods grow so quickly but with weak wood, they’re commonly used to produce low-value wood items like pallets, shipping crates, and wood pulp. Some people have even used the cottony fibers from the seeds to stuff pillows or plush toys.