Big Leaf Maple
Acer macrophyllum
Common throughout the Tri-Cities in natural areas, parks, and older neighbourhoods. Often the first tree to colonize disturbed sites.
Identification
25-35m (80-115ft)
Up to 1.5m diameter with grey-brown bark that develops ridges and furrows with age
Largest maple leaves in North America, 20-35cm across with 5 deep lobes
Produces paired winged seeds (samaras) in late summer, hanging in clusters
Key Identifying Features
- Enormous five-lobed leaves (largest of any maple)
- Often covered in moss and ferns on trunk and branches
- Yellowish spring flowers hanging in clusters
- Paired helicopter seeds
- Bark often supports entire ecosystems of mosses and lichens
Identification Photos
Click any photo to enlarge. Photos help with identification but may vary by age, season, and location.
Tree Care
Watering
Prefers moist, well-drained soil. Tolerates dry summers but may drop leaves early under stress.
Pruning
Prune to maintain structure and remove deadwood. Can handle significant pruning if needed. Remove water sprouts regularly.
Best time: Late fall to early winter when dormant (to minimize sap bleeding)
Common Issues
- Aphids causing honeydew and sooty mold
- Verticillium wilt (fungal disease)
- Tar spot (cosmetic leaf disease)
- Heavy moss growth adding weight to branches
Maintenance Notes
Moderate maintenance due to prolific seed production and leaf drop. Regular deadwood removal recommended.
Root System
Aggressive, spreading root system
Roots commonly extend 2-3x the canopy width
Potential Concerns
- Frequently damages sidewalks and driveways
- Can infiltrate sewer and water lines
- Surface roots make lawn maintenance difficult
- Known for cracking foundations if planted too close to structures
Hazard Assessment
Common Failure Modes
- Heavy branch failures, especially when wet or mossy
- Codominant stem failures
- Sudden branch drop in summer (summer limb drop)
- Decay in old pruning wounds
Warning Signs to Watch For
- Dead branches in crown
- Cracks at branch unions
- Fungal conks on trunk or branches
- Excessive lean developing
- Wilting or browning leaves in part of the crown (may indicate Verticillium)
Removal Considerations
Key Considerations
- Heavy, dense hardwood requires powerful equipment
- Often develops multiple leaders requiring careful rigging
- Extensive root system can damage underground infrastructure
- May have significant wildlife habitat value
- Wood is valuable for woodworking
Permit Notes
Protected in most municipalities. Often grows near streams where additional environmental permits may be required.
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