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!
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.
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.
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!
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.
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.