Identifying the White Fluffy Seeds in Eugene, Oregon's Spring Air

Cottonwood "Snow": The Annual Spring Spectacle in Eugene

The clouds of white, fluffy fibers drifting through Eugene each spring (typically April–June) are seeds of the Black Cottonwood (Populus trichocarpa), the largest native broadleaf tree in the Pacific Northwest.

Why It Happens

• Female cottonwoods release millions of tiny seeds attached to silky hairs (coma) that act as parachutes.
• Wind disperses them over kilometers—nature's ingenious colonization strategy.
• Peak release coincides with warm, dry days after winter rains.

Ecological Role

• Colonize bare riverbanks, floodplains, disturbed sites.
• Food for birds, insects; nesting material.
• Rapid growth stabilizes soil, shades streams for salmon.

For Residents

• Not pollen: Cottonwood pollen (allergenic) is released earlier (Feb–Mar) from male trees—invisible, yellowish.
• Messy but harmless: Seeds clog screens, pool filters, AC units. Vacuum or hose off.
• Fire hazard: Accumulated "cotton" is highly flammable; clear from structures.

Other Possibilities

Willow (Salix) and aspen (Populus tremuloides) also produce similar fluff, but cottonwood dominates Eugene's riparian corridors (Willamette, Amazon Creek).

Enjoy the "summer snow"—it's a sign of healthy rivers and a thriving native giant.