Cottonwood (Tree)
Description
Cottonwood trees (Populus species, section Aigeiros) are fast-growing, large deciduous trees in the willow family (Salicaceae). They have broad canopies and triangular or heart-shaped leaves that flutter in the breeze. Cottonwoods are famous for the fluffy white seeds that fill the air in late spring and early summer — but here’s the thing: it’s the pollen released earlier in spring, not the cotton-like seeds, that causes allergies. The seeds just look dramatic. Common species include eastern cottonwood (Populus deltoides) and black cottonwood (Populus trichocarpa).
Allergy Symptoms
Cottonwood pollen causes:
- Sneezing and runny or congested nose
- Itchy, watery, red eyes
- Coughing and throat irritation
- Asthma flare-ups and wheezing
Cottonwood is related to willows and aspens, and shares allergenic proteins with them — if you’re allergic to cottonwood, you may react to those too. Some people experience Oral Allergy Syndrome (OAS) with foods like apples and sunflower seeds, though this is less common than with birch allergies.
Typical Pollination Period
Cottonwood trees pollinate in early to mid-spring, from late February through April, starting earlier in warmer southern regions. Don’t be fooled by the fluffy seeds in late spring — those aren’t the problem. The allergenic pollen was released weeks earlier.
Geographic Distribution
Cottonwood trees grow across the Northern Hemisphere:
- North America: Especially common in central and western regions, particularly near rivers, streams, and floodplains
- Europe: Widely cultivated and naturally occurring in temperate regions
- Asia: Common in temperate areas, especially northern China and parts of Siberia
Tips for Allergy Sufferers
- Check local pollen forecasts during early spring (not when you see the cottony seeds)
- Keep windows closed and use HEPA air purifiers
- Shower and change clothes after being outside
- Antihistamines or nasal corticosteroids can help — ask your doctor
- Remember: the cotton-like fluff isn’t the allergen; pollen season peaks earlier
- For persistent symptoms, consider allergy testing or immunotherapy