Grand Fir Abies grandis

Grand fir is a true fir that grows on moist, productive sites. West of the Cascades it is mostly a low-elevation valley tree and a minor part of wet coastal forests, while in the Cascades and northern Rockies it grows on moist slopes (USFS Fire Effects Information System). Field guides rarely name grand fir on its own; they say “true firs.” Mushrooms of Cascadia (Siegel & Schwarz) lists true firs among the favored hosts of the king bolete at high elevations, the fib king, matsutake in drier forest, the true-fir morel (Morchella snyderi) and several waxy caps (Hygrophorus). Grand fir itself is named as a host of the toxic red-pored bolete and of the wood-decay fungi described below.

This is a large tree: mature heights are 140 to 200 feet along the coast and 131 to 164 feet inland (FEIS). Look at the needles: they are flat, blunt-tipped, and arranged in two rows on opposite sides of the twig, giving the branches a flat spray.

The bark changes with age. Young trees have thin, smooth, gray bark with resin blisters. Mature trees have furrowed, moderately thick bark and are moderately resistant to fire (FEIS). The female cones stand upright on the upper branches and break apart on the tree, so intact cones are not found on the ground the way spruce cones are.

Grand fir ranges from southern British Columbia through western Washington and Oregon, and inland through Idaho and Montana. West of the Cascade crest it occurs mainly in moist valley bottoms and is a minor component of wet, dense coastal forests. In the Cascades it grows up to about 4,000 feet in Washington and about 6,000 feet in Oregon (FEIS). Grand fir does not exude heavy pitch over wounds, so decay fungi can enter through branch stubs and fire scars.

Associated Mushrooms

The red-pored bolete and honey mushroom are documented with grand fir, and conifer chicken of the woods favors true firs. The lobster mushroom and king bolete grow in conifer forests that can include grand fir, but neither is tied to it specifically.

Lobster Mushroom

Hypomyces lactifluorum

This parasite covers Russula brevipes, a mycorrhizal mushroom of many conifer forest types, and turns it into a firm orange-red edible. Eat only firm specimens (Siegel & Schwarz).

Parasitic Edible

King Bolete

Boletus edulis

Two main habitats: Sitka spruce on the coast, and higher-elevation Cascades conifer forest, where true firs are named hosts. Fruits in summer and fall in the mountains.

Mycorrhizal Choice Edible

Honey Mushroom

Armillaria ostoyae

A root-rot pathogen of grand fir (FEIS) that also lives on dead wood. Fruits in clusters, usually in fall. Armillaria is a species group; cook thoroughly and be sure of the identification.

Parasitic Saprotrophic Caution

Chicken of the Woods

Laetiporus conifericola

Orange-and-yellow shelves on standing trees, stumps and logs of conifers, especially true firs and spruce; it causes a brown rot (Siegel & Schwarz). Eat only young, soft brackets, cook thoroughly, and sample sparingly at first.

Parasitic Edible

Red-pored Bolete

Rubroboletus pulcherrimus

Red pores, a reddish netted stem, and flesh that stains blue. Rare, under conifers, most often grand fir and western hemlock (Siegel & Schwarz). Red-pored boletes are quite rare here, but they are the group to avoid.

Mycorrhizal Toxic

Photos: Grand Fir — Lauren Bosch (CC0) · Lobster Mushroom — © Drew Henderson, CC BY-SA · King Bolete — rockybajada (CC0) · Honey Mushroom — © ahabo, 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.