Black Cottonwood
Populus trichocarpa
Found along rivers and floodplains throughout the Tri-Cities. Common along the Fraser River, Pitt River, and in Pitt Meadows agricultural areas.
FormbarkbarkHow to recognise it
Height
30-50m (100-165ft), one of the tallest hardwoods in North America
Trunk
Up to 2m diameter with deeply furrowed grey bark on mature trees
Needles
Heart-shaped to triangular (5-15cm), dark green above, silvery underneath, with fine-toothed edges
Cones
Produces cotton-like seeds in late spring that cover the ground like snow
Quick check
- Distinctive cotton-like seed dispersal in spring
- Resinous, fragrant sticky buds
- Leaves flutter and shimmer in the breeze
- Fast-growing - can add 2m per year
- Deeply furrowed bark on older trees
Photo guide
6 things to look for: photographs coming
Care
Watering. Extremely water-demanding. Naturally grows along rivers and in floodplains.
Pruning. Not typically pruned as it responds with excessive water sprouts. Remove hazardous limbs only. Best time: Winter when fully dormant to minimize sprouting response
Maintenance. High maintenance due to constant debris, aggressive roots, and storm damage cleanup. Generally not recommended for residential planting.
Common issues
- Extremely aggressive root system
- Messy cotton production in spring
- Brittle wood prone to storm damage
- Poplar borer beetle
- Cytospora canker
Roots
Extremely aggressive, invasive root system Roots can extend 3-4x the tree height, seeking water sources
Hazards
Windfall risk
High
Branch drop risk
Very High
Warning signs to watch for
- Cavities or hollows in trunk
- Dead branches in crown
- Leaning trunk
- Weeping wounds on trunk
- Fungal fruiting bodies
Removal considerations
Difficulty: HighTypical cost: $$$-$$$$- Very tall trees requiring specialized equipment
- Brittle wood makes climbing hazardous
- Aggressive roots often extend far from tree
- Stumps will vigorously resprout if not treated
- Often located in riparian areas with permit requirements
Permits
Permit thresholds vary across the region: 15cm or 5m tall in Port Coquitlam, 20cm in Anmore, Coquitlam, Maple Ridge, Pitt Meadows, New Westminster and Delta, 30cm in Port Moody and Surrey, and 30.5cm for conifers in Burnaby (Belcarra regulates only trees 5m+ in its mapped permit areas). Cottonwood is explicitly excluded from the 'significant tree' rules in both Port Coquitlam and Maple Ridge, so replacement obligations are usually lighter. The ordinary permit threshold still applies, and because cottonwoods so often stand near water, streamside rules are the constraint that actually bites.
Tree bylaws by city