Bigleaf Maple Acer macrophyllum

Bigleaf maple is a large hardwood of the Coast Ranges and Cascade foothills (USFS FEIS). It is an arbuscular-mycorrhizal tree rather than an ectomycorrhizal one, so it has no chanterelle or bolete partners; the mushrooms in its habitat are mostly wood-decay species on its dead wood. Oysters, late oysters, deer mushrooms and honey mushrooms are among them.

Bigleaf maple has the largest leaves of any North American maple, 4 to 10 inches across, with deep palmate lobes. It is typically about 50 feet tall at maturity and sometimes more than 80, with a broad, rounded crown and thin, furrowed bark (FEIS). Mosses, liverworts and ferns, licorice fern (Polypodium glycyrrhiza) among them, often hang from its branches.

Bigleaf maple prefers moist to mesic sites, including stream corridors and lowland bottoms. In Washington and Oregon it grows from sea level to about 3,000 feet (FEIS). It often takes advantage of gaps and open stands and grows in mixed hardwood-conifer forests with red alder and Douglas-fir.

Bigleaf maple forms arbuscular mycorrhizae, a different kind of partnership from the ectomycorrhizae of conifers, and arbuscular fungi do not produce the mushrooms foragers hunt. Its mushrooms are therefore mostly wood-decay species growing on its dead wood. The wood is used for lumber, furniture, flooring and veneer, and the sap can be made into syrup, though the yield is less than from sugar maple (FEIS).

Associated Mushrooms

The mushrooms below grow on dead or dying hardwood, including bigleaf maple. Late oyster is the one most closely tied to maple (and to red alder).

Oyster Mushroom

Pleurotus ostreatus

Grows in overlapping clusters on dead wood, mostly hardwoods and especially alder (Siegel & Schwarz, Mushrooms of Cascadia); bigleaf maple is another host. Two main fruitings, spring and fall, with smaller numbers whenever it is wet.

Saprotrophic Edible

Deer Mushroom

Pluteus cervinus group

Decays wood of both hardwoods and conifers, so maple is one possible host among many. Brown cap and free gills that turn pink with age. Telling it from Pluteus exilis can take DNA.

Saprotrophic Caution

Artist’s Bracket

Ganoderma applanatum

Perennial woody bracket on lower trunks, stumps and logs, often of hardwoods but also conifers; maple is one possible host. The white pore surface stains brown when scratched, hence the name. Not edible.

Saprotrophic

Late Fall Oyster

Sarcomyxa serotina

Grows on decaying logs and dead trees, almost always bigleaf maple or red alder (Siegel & Schwarz). Fruits more in cold weather, with scattered fruitings through the rainy season. The viscid olive cap sets it apart from true oysters. Edible but not highly regarded.

Saprotrophic Edible

Honey Mushroom

Armillaria species

Honey mushrooms fruit in clusters at the base of trees and on roots in fall. Armillaria nabsnona grows on a wide range of trees but prefers alder and bigleaf maple (Siegel & Schwarz); A. ostoyae, shown, mainly attacks conifers. Cook thoroughly, which often lowers the chance of a reaction.

Parasitic Saprotrophic Caution

Photos: Bigleaf Maple — Quillipede (CC0) · Late Fall Oyster — Jean-Paul Boerekamps (CC0) · Honey Mushroom — © Harrison Reber, CC BY.

Sources: Mushrooms of Cascadia (Siegel & Schwarz, 2024); MycoMatch (© Ian Gibson), a compilation of published descriptions through which most other field-guide authors named here are quoted.