Welcome to Mushroom Monday for April 9, 2018
Posted by Gary Hunt
Snowbank fungi are species that fruit adjacent to melting show. They are represented by a diverse array of species found in forested regions, primarily higher elevations, of western North America ranging from New Mexico to Canada. They may be saprophytic (decomposers), symbiotic (mycorrhizal) or even pathogenic.
Snowbank mushrooms develop in the subnivean zone under snow. Pushing up through ice crystals, they emerge near the melting edge of snow. John Richter photo
Snowbank fungi are recognized as a distinct ecological group that was first described by William Bridge Cook in 1944. It seems odd that a fungal mycelium would be able to produce mushrooms under such cold conditions and surrounded by snow. They can accomplish this because the mycelium can remain actively growing during winter under deep snow. This is possible because of the air space that forms between the snow and soil. This space is called the subnivean zone (from the Latin meaning, “under snow”). These spaces form because of the warmer temperatures close to the ground from heat deep in the soil. This heat is retained in the spaces due to the low thermal conductivity of snow. Water vapour moves slowly upward through the air spaces between snow ice crystals. The result is an ideal, humid chamber for mushrooms to form.
On a side note, the subnivean zone is also important habitat for animals in winter. These include mice, voles, shrews, and around Kamloops, many pocket gophers. It is an insulated zone of relatively constant temperature that provides a degree of protection from predators. Coyotes, foxes, owls and other predators can hear animal movement in the subnivean and pounce from above. Unfortunately, snowmobiles and ATVs can collapse this important habitat.
Hygrophorus goetzii is an attractive, small mushroom that is known to fruit only in spring near melting snowbanks in conifer forests. It has a pale-pink, slimy cap. Notice the space it has formed in the snow. The temperature of the mushroom is slightly above freezing so it makes its own “tree well.”
The temperature of the mushroom tissue is slightly above freezing. This small amount of heat creates an open space in the snow. epod.usra.edu photo
Mycena nivicola emerges from woody debris near melting snow in the spring. It grows at higher elevations under pine and fir (Abies). The cap is olivaceous-brown and the stem is lemon-yellow at the top.
Mycena nivicola occurs at higher elevations under pine and fir (Abies) trees. mycoweb.com photo
Mycena overholtzii is a very large member of the Mycena genus. It grows in dense clusters on decaying conifer wood near melting snow. The base of the clustered stems is covered with white mycelium.
Mycena overholtzii is a large species of Mycena that grows in clusters on decaying wood. mycoweb.com photo
Gyromitra montana is known as the “snow mushroom.” In older references it may be named Gyromitra gigas. It is recognized by its short, stocky build and an orange-brown, convoluted and brain-like cap. It occurs on well-rotted conifer wood near melting snow, but is also found away from snow. Species of Gyromitra contain the toxin monomethyl-hydrazine (MMH) which can be fatal in high doses.
Gyromitra montana has a convoluted and folded cap. It is not restricted to snowbank habitats and is also found in humus and on well-rotted wood under conifers. mycoweb.com photo
Snowbank mushrooms are an intriguing group of fungi adapted for fruiting in early spring. Be on the lookout for them as you are out walking in higher elevation forested areas.
Post revised to update images and formatting – 10/2025 – DAS