Bigleaf Maple

Bigleaf maple announces itself by its leaves before you identify the tree: they are the largest leaves on any native maple, often 12 inches across, deeply lobed, and bright green. You find this tree in moist bottomlands, along stream banks, and in the richer soils of foothill forests throughout Western Washington. The trunk is often short and thick, with ascending branches that form a broad, rounded crown. The bark is smooth and gray on young trees, becoming thick, furrowed, and dark with age. In spring, drooping clusters of greenish-yellow flowers appear before the leaves fully unfurl; by summer, moss and ferns colonize the trunk and lower branches in the mild, humid climate, creating a richness of epiphytic life.

In Western Washington, bigleaf maple is a fast-growing pioneer species that thrives in sun to part shade with moist, well-drained soils. The tree is hungry for moisture and nutrients; in dry summers it exhibits leaf scorch, and in compacted or poorly drained sites it declines. Its shallow, aggressive root system can damage sidewalks and drainage lines, so site it away from hardscape. The wood is soft and weak; heavy snow loads or storm winds break branches readily, especially in multi-stemmed specimens. Multiple diseases affect this tree: bigleaf maple decline (stem canker and bleeding canker) appears on stressed trees, and anthracnose defoliates foliage in wet springs. As a legacy tree, bigleaf maple is excellent for shade and wildlife; its fast growth and large leaves create density quickly. Expect a 30-40 year productive lifespan before disease pressure accelerates.