Mycorrhizal Fungi

A patch of red mushrooms with white spots growing out of branches and dead leaves.
Amanita muscaria, or the fly agaric. The white patches on the cap are remnants of the "universal veil" that encapsulates the mushroom in the early stages of development.

NPS Photo

Some species of fungi form complex symbiotic relationships with the roots of trees and other plants. We describe these relationships as mycorrhizal (from the Latin myco-of fungi, and rhiza-root). Though the dynamics of these relationships vary, often the mycelial network provides extra water and nutrients such as phosphorus and nitrogen to the plant and, in return, the plant provides carbohydrates produced through photosynthesis. Because mycelial networks are so efficient at extracting moisture and nutrients from the soil, they can help their plant partners survive harsh conditions such as prolonged drought and poor soil quality. A great majority of vascular plants rely on these symbiotic associations with fungi.

Broad research indicates that mycorrhizal fungi can also connect plants to each other in meaningful ways. Certain fungi have demonstrated the ability to stimulate defense signaling, or immune response, within a community of plants when an individual plant is injured or threatened by a parasite! Mycelial networks can also transport nutrients from healthy, well-established trees to nourish saplings or struggling trees. Even plants of different species can participate in this type of nutrient exchange. As scientists continue to examine these complex interactions, one thing has become clear: fungi form a vital part of a healthy and resilient forest ecosystem.

While the majority of mycorrhizal fungi do not produce mushrooms at all, many well-known mushrooms do form these connections with plants. Paying attention to these relationships can help you be a more successful mushroom hunter. Knowing what plants your target mushroom likes to grow near can help you select likely habitats and potentially rule out poisonous lookalikes!

A very large mushroom supporting a ranger flat hat.
An impressive king bolete (Boletus edulis or similar), donning a park ranger hat for scale!

NPS/B. Garcia Photo

Boletus edulis group

Common Names: King bolete, porcini, penny bun, cep
Description: Medium to large cap, various in color, but generally some shade of brown. Underside of cap reveals a spongy surface of tubes (no gills), which begin white, but turn yellow and finally olive with age. Upper surface of the stalk has fine white net-like pattern known as “reticulation.” Flesh does not change color when cut or bruised.
Ecology: Mycorrhizal with many trees including spruce, pine, hemlock, and fir.
Comments: The name Boletus edulis is here a stand-in for several similar species that occur in our area. These distinctive mushrooms can be observed in both the subalpine and lowland forest ecosystems of Mount Rainier National Park.

A cluster of pale yellow mushrooms erupting out of moss.
A cluster of Amanita aprica erupting from the ground.

NPS/B. Garcia Photo

Amanita aprica

Description: A very common mushroom at Mount Rainier in the spring, A. aprica has a yellow to orange cap that is covered with a frosty white coating. This white layer is the remains of the “universal veil,” which covers and protects the mushroom in the early stages of its development. Gills white to cream; fragile ring on stalk, with volva present at base.
Ecology: Mycorrhizal with Douglas-fir and pines.
Comments: Poisonous! All Amanitas should be avoided as this genus contains several toxic and deadly species. This beautiful mushroom is often observed in May and early June in Mount Rainier’s lowland forests. A similar species, which occurs in the fall, Amanita muscaria, is red-capped, and has distinct white or yellow patches on the cap, rather than a frosty layer. It is also poisonous.

One large and two small white mushrooms pulled out and resting on moss. One of the small mushrooms is cut in half length-wise to show the solid white interior.
Tricholoma murrillianum, the American matsutake or pine mushroom.

NPS/B. Garcia Photo

Tricholoma murrillianum

Common names: Matsutake, pine mushroom
Description: Large, dense, and hard white fruit body covered with brownish patches or scales. A membranous veil beneath cap conceals white gills until it breaks at maturity. Smell reminiscent of cinnamon, sometimes with a displeasing component, or, as author David Arora famously describes it, like “red-hots and dirty socks.” Flesh dense, white, and unchanging when cut.
Ecology: Mycorrhizal, associating primarily with Douglas-fir, but also with other conifers.
Comments: Fruiting in the fall after the rains return, the matsutake is a favorite among foragers. This mushroom is economically significant, as millions of dollars’ worth of foraged matsutake are exported to Japan each year from the Pacific Northwest. They are often difficult to find, as they sometimes fruit partially underground. Identification is tricky and must be confirmed by an expert to rule out poisonous species!

A tan mushroom with a wavy cap pulled out and resting on the forest floor.
Cantharellus formosus, a locally common chanterelle species. Note the blunt ridges running down the stalk.

NPS/B. Garcia Photo

Cantharellus formosus

Common Name: Pacific golden chanterelle
Description: Entire fruiting body orange to pale orange-yellow. Margin (edge) of cap often wavy, with edges inrolled, at least when young. Underside lined with blunt ridges (NOT gills) that run down the stalk. Interior flesh whitish, firm.
Ecology: Mycorrhizal with conifers, including Western Hemlock
Comments: One of at least three very similar species of chanterelles that grow in Washington. In recent years, several new species of chanterelles have been “discovered.” Taxonomic efforts to order and understand the subtle diversity of this genus are ongoing.

Three mushrooms growing out of moss, two brown capped, one with a shinier red cap.
Suillus lakei (above and center) growing alongside Gomphidius subroseus (below). G. subroseus gets at least some of its nutrients by parasitizing the mycelium of the Suillus.

NPS Photo

Suillus lakei

Common Name: Western painted Suillus
Description: Faded brick-red to brown, scurfy cap surface. Underside of cap covered in yellowish, irregular, angular pores. Upper section of stem yellow, with a scurfy ring below (remnants of the partial veil). Often scaly, with reddish streaks below ring. Base of stem usually staining dark bluish green when cut.
Ecology: Mycorrhizal with Douglas-fir trees.
Notes: Suillus lakei often fruits in the vicinity of another mushroom, Gomphidius subroseus, which parasitizes S. lakei, feeding off of its mycelial network.


Last updated: April 21, 2021

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