of my first encounters with the "Snowbank fungi" was glissading
down a snowy slope, when suddenly just before I hit bare ground,
hordes of shiny gray mushroom heads appeared unexpectedly from
the snow glistening in the high elevation sunlight. It quite
took my breath away.
Later I learned that deep
in the high elevation forests of western North America where
snowbanks linger long into summer months, a unique group of macrofungi
flourishes on the melt waters released by the white remnants
of winter. Fruiting bodies initiate in the subnivean zone and
push up through the snow as it melts around them forming small
caverns. At the snow-soil interface temperatures hover around
freezing. As warm air and sun reduce the snowbanks, an array
of mushrooms and cup fungi is revealed along margins in the adjacent
melt-water zone. As the season progresses they remain as silent
sentinels marking the outline of defunct snowbanks with their
The "Snowbank fungi" are
a consistent feature of high elevation western conifer forests
in spring and early summer. They are reported primarily from
the Rocky Mountains and Cascade Range, but their distribution
stretches from southern Canada to northern New Mexico at elevations
of 1500 to 3800 m. I have observed them en masse in Colorado,
Idaho, Montana, Wyoming, and Canada and they are well known in
the Pacific Northwest, the Sierra Nevada range of California
and the Wasatch Mountains of Utah. Many of the snowbank fungi
are endemic to western North America. Others also occur outside
the West but not in this unique ecological niche. Moser (2004)
states "we have nothing comparable in Europe".
The "Snowbankers" appear
to be a unique western North American phenomenon. They are not
associated with the open snow-beds of arctic and alpine habitats,
nor are they associated with glaciers. They are not the typical
spring mushroom flora, although a few overlap chronologically
with this group. They have not been reported from the eastern
USA as an ecological group.
The "Snowbank fungi" are
well-distributed where certain conditions are met. They proliferate
in regions of high elevation with short, cold summers where snowbanks
remain until July. Sufficient elevation is necessary for a deep
snowpack in mature forests suffused with downed logs and abundant
litter and woody debris. Spring and summer nights must be cool
enough to retain the snowbanks, and days warm enough to provide
melt water for the fungi which fruit as the soil warms and dries.
The fungi can occur on steep slopes or level ground, but snowbanks
persist longer on northern slopes and in deep shade where fruiting
is protracted. Fruiting can stretch into July and August at higher
elevations. The "Snowbank fungi" are associated mostly with the
spruce-fir zone (mixed conifers), and particularly with Engelmann
spruce (Picea engelmannii Engelm.), subalpine fir (Abies
lasiocarpa [Hook.] Nutt.), and lodgepole pine (Pinus contorta Laud.),
although they also occur in mixed whitebark pine (Pinus albicaulis Engelm.)
forests. It is this particular set of trees that provides enough
shade to protect against a quick snowmelt (unlike larch or other
deciduous trees at high elevations). These trees are also associated
with the mycorrhizal "Snowbankers" such as certain species of Hygrophorus and Cortinarius and
they provide woody substrates for the saprobic species as well.
This taxonomically diverse
group was first reported as an ecological assemblage by Wm Bridge
Cooke in a 1944 article (Cooke 1944) on the fungi of Mount Shasta,
California. This was followed by Subalpine fungi and snowbanks (Cooke
1955) where he related the details of the macrofungi consistently
fruiting near snowbanks in spring. The names of the fungi he
reported are out- of-date (but recognizable). This set of fungi
was subsequently called the "Snowbank flora" by Alex Smith in A
Field Guide to Western Mushrooms (1975). He reported particular
species near snowbanks in Idaho where he spent summers, but did
not treat the group as a whole in an article. In 1965 Orson K.
Miller, Jr. contributed the brief but informative Snowbank
Mushrooms in the Three Sisters Wilderness Area (Miller 1965).
Both Smith and Miller described several new species of "snowbank
mushrooms" and linked additional taxa to western snowbanks in
a number of publications (references at end). Ammirati and Moser
joined in to help delineate snowbank Cortinarius taxa,
an ongoing process. More recent literature has updated the nomenclature
(Bessette et al. 1995, Miller & Miller 2006, Redhead et al.
Moser described the snow-bank
fungi as a uniquely North American phenomenon (2004). This insight
brings with it the realization that the "snowbank fungi" are
dependent on a particular habitat limited to forest-covered mountain
slopes with special climatic, geographic, and biological components.
These restricted ranges are directly (habitat reduction, forest
thinning, fire) and indirectly (global climate change) impacted
by human activities.
THE SNOWBANK FUNGI
The snowbank fungi are
a taxonomically and ecologically diverse group of fleshy fungi
that include both Basidiomycota and Ascomycota adapted to the
unique microclimate provided by remnant snows in high-elevation
conifer forests. Hygrophorus and Cortinarius species
are mycorrhizal genera and have a mutually beneficial relationship
with conifer trees. Other fungi are saprobic and decompose logs,
twigs, cones, and organic debris, except for Caloscyphe fulgens which
is a seed pathogen.
All snowbank species of Hygrophorus are
endemic to North America, with the exception of H. marzuolus which
is reported from Europe in spring but not necessarily with snowbanks
(Moser 1955). Hygrophorus species can initiate fruiting
in the subnivean zone and H. goetzii has been observed
under 7-10 cms of solid ice where snow has melted and refrozen
(Miller 1965). Hygrophorus goetzii has a small viscid
pinkish-cream fruiting body (Hesler and Smith 1963, Miller 1965,
1967). Hygrophorus marzuolus (Fr.) Bres. and H. caeruleus O.K.
Mill. have large, fleshy bluish-gray sporocarps, but only the
latter has a strong smell of rancid meal (Miller 1984, Bessette
et al. 1995). Hygrophorus subalpinus A.H. Sm. is a robust
pure white mushroom with a gelatinous veil at first, and is sold
in markets as an edible in the Pacific Northwest. Neohygrophorus
angelesianus (A.H. Sm. & Hesler) Singer combines the
macro-features of Hygrophorus and Clitocybe, and
produces small brownish-gray mushrooms with drab purple brown
tints and decurrent gills; the red reaction of fresh gill and
stem tissue to KOH is distinctive (Smith and Hesler 1942, Miller
1965, 1967, Bessette et al. 1995).
Several species of Cortinarius are
associated with snowbanks (Miller 1965) and others occur later
in the spring grading into the typical spring mushroom flora. Cortinarius
ahsii McKnight first described by McKnight is a nondescript
brown mushroom with a bright yellow veil named for Alexander
H. Smith (his initials: A.H.S.); it is likely synonymous with C.
zinziberatus (Fr.) Fr. of Europe which is not reported with
snowbanks according to Moser. While this species became a well
known "Snowbanker", it is often not the most common snowbank Cortinarius species.
Subsequent study by Ammirati, Moser and Miller revealed at least
two other look-alikes that fruit at the same time which can be
sorted out with the help of a UV light. This includes "C.
flavobasalis" which fluoresces orange at the base (fresh
young fruiting bodies!) and "C. flavoroseus" with a veil
and flesh (cut it open) that fluoresce bright yellow. The latter
two species have provisional names and they are currently under
study for publication. Ammirati states that a number of the snowbank Cortinarius subgen. Telemonia are
not named, and Moser notes that particular Cortinarius species
from subgenus Phlegmacium can also be present. Out of
four new taxa of the genus Cortinarius dealt with in Moser
(2002), at least one (Cortinarius auchmerus M.M.Moser)
might be associated with snow banks. Occasionally particular Entoloma species
are reported next to snowbanks in spring.
Two of the most common
snowbank fungi, Clitocybe glacialis Redhead, Ammirati,
Norvell & M.T. Seidl (=Lyophyllum montanum A.H. Sm.)
and C. albirhiza, are considered decomposers. Clitocybe glacialis is
recognized by its overall silvery gray color which glistens in
sunlight reflected off snow (Smith 1957, 1975; Miller 1967). Clitocybe
albirhiza H.E. Bigelow & A.H. Sm. is a related rather
nondescript pale brown mushroom of the same size that can be
recognized by the copious white subterranean rhizoids at its
base (Bigelow and Smith 1962). Mushrooms of both emerge from
the subnivean zone, and persist after the snow has melted, likely
due to slow decomposition in a cool climate. Interestingly, as
they decompose, the two species become difficult to distinguish
as both become a watery yellow-brown.
Mycena overholtsii A.H.
Sm. & Solheim fruits in clusters on decorticated logs buried
in the snow (Smith 1979). As snow recedes around the log, the
mushrooms mature in moist snow chambers. The long, hirsute stipe
is often buried in deep cracks in the woody substrate. It is
recognized by its rather large size for a Mycena, a gray-brown
striate bell-shaped cap and substantial mycelium on the lower
part of the stem. Hence the common name "fuzzy foot". Other early
species of Mycena are typically much smaller. Lentinellus
montanus O.K. Mill. is another agaric found on logs near
snow, but here the brown shell- shaped caps lack a stem. Melanoleuca
angelisiana A.H. Sm. is characterized by a gray-brown pileus,
contrasting white gills and a dark stipe (Smith 1944, Bessette
et al. 1995). It fruits on the ground near snowbanks and in other
habitats as well. Melanoleuca species have a white spore
print and amyloid ornamented spores (somewhat similar to those
of Russula). Macroscopically they often have a 'twisted-striate'
Two western Stobilurus
species fruit in early spring near snowbanks, S. albipilata (Peck)
Wells & Kempton and S. occidentalis Wells & Kempton,
and they are delineated on microscopic characteristics (Redhead
et al. 1980). Both are tiny collibioid mushrooms and it is
helpful to follow their long stems down to buried cones for
confirmation of identification. Although not strict "Snowbankers",
they do occur at the same time and in the same habitats. All
of the species in the preceding five genera (Clitocybe, Mycena Lentinellus, Melanoleuca and Strobilurus)
have white spores and are North American species.
Nivatogastrium nubigenum (Harkn.)
Singer & A.H. Sm. is a unique gastroid fungus related to
the genus Pholiota (Singer and Smith 1959, Miller 1965).
The cap never opens to release the spores and this is hypothesized
to be is an adaptation to extreme cold and drought. Cooke (1955)
reported that squirrels eat the fruiting bodies and disseminate
the spores, and he described specimens set out on stones and
branches to dry for later use. The caps are often buried in snow
and are revealed only at maturity. There are no other secotioid
fungi known on wood, and this species is restricted to North
America. I have collected it near McCall Idaho on logs in the
spruce-fir zone, and Cooke collected it on Mount Shasta in California.
Interestingly, Nivatogastrium baylisianum E. Horak has
been reported from alpine areas in New Zealand (Horak 1971).
include several wood decomposers in the polypore and jelly fungus
groups. There is some evidence that the hyphal growth of Tyromyces
leucospongia) (Cooke & Harkn.) Bondartsev & Singer
(white sponge polypore) is maximized at 12 to 16 deg. C, and
that it can complete its life cycle below 7 deg. C. (Bessette
et al. 1995). It is recognized as a white, soft marshmallow-like
polypore with angular pores found on downed logs at snowmelt.
Many of the snowbank fungi do not grow well in culture and have
therefore not been shown to be psychrophilic. The bright orange
soft polypore with ragged teeth found in the same habitat is Pycnoporellus
ablboluteus (Ellis & Everh.) Kotl. & Pouzar (orange
sponge polypore). Guepinopsis alpina (Tracy & Earle)
Brasf. (lemon drops) is a gelatinous basidiomycete and some jelly
fungi are able to sporulate after being frozen while fully hydrated
(Ingold 1982), an adaptation well-suited to cold climates. Miller
(1981) cites this as the most prolific species during snowmelt
in the western mountains, and we have shown it prefers cold temperatures
for fruiting ( Cripps, unpublished).
Numerous ascomycetes are
associated with snowbanks, and several are reported here, although
more certainly exist and particularly where melting snowbanks
are combined with burned ground. Caloscypha fulgens (Pers.)
Boud., an orange cup fungus with a bluish exterior (especially
when handled), also occurs in Europe. It is a seed pathogen on
spruce (Picea) and kills dormant seeds during stratification
(cold treatmet) in cool, moist soils (Paden et al. 1978). Sarcosoma
mexicanum (Ellis & Holw.) Paden & Tylutki is a black
cup fungus with a swollen gelatin-filled base (Tylutki 1979)
that functions as a moisture reserve during spore maturation.
It often fruits with the snowbank flora, but is not a strict
snowbank associate. I have observed it in Oregon, Idaho, and
New Mexico, and it is reported from western Montana. Plectania
nannfeldtii Korf fruits in the subnivean zone and the black
stalked cups emerge as snow melts in pockets around them (Miller
1965, 1967; Seaver and Shope 1930; Tylutki 1979). The rubbery
ascocarps are remarkably durable and endure long after the snows
are gone. It was first described by Swedish mycologist Nannfeldt
on a visit to Colorado in the early 1900s (Evenson 1997).
A set of Myxomycetes (slime
molds) are also known to occur near snow. They are more commonly
called the "nivicolous" myxomycetes and they are protists not
fungi. They have been called the snowbank slimemolds, but "snowbank" is
defined in a broader sense for these organisms to include subalpine
snowbanks and also alpine snowbeds. Habitats include proximity
to snow in alpine, arctic, and high elevation habitats around
the world and in the eastern USA. For photos see link on myxo-specialist
Steve Stephenson's website http://www.myxowb.com/snow.htm.
When collecting "snowbank
fungi", it is important to record the particulars of habitat
and location since this specialized niche is easily overlooked
in forest management. If snowbank fungi truly are restricted
to the western US and require certain biotic and abiotic conditions,
only those who recognize them can provide information on their
distribution and identify potential threats. They are worth getting
to know for their ecology, their uniqueness, as well as for their
This paper is dedicated
to the memory of Orson K. Miller, Jr., a mycologist and wonderful
mentor who introduced me to the snowbank fungi by in 1985 when
our mycology class at the Flathead Lake Biological Station collected
snowbank fungi on the steep slopes to Jewel Basin in western
Montana. I had collected them in Colorado for ten years previously,
but their import had somehow escaped me. I would like to thank
Joe Ammirati and Egon Horak for their comments to the first draft
of this article.
TABLE 1. Snowbank-associated
fungi in the western USA.
ECOLOGY OF TAXA
croceus (Schaeff.) Gray
Cortinarius "flavobasalis" McKnight & Moser
Cortinarius "flavoroseus" nom.
subalpinus nom. prov.
nubigenum (Harkn.) Sing & A. H. Smith
Mushrooms (white spores)
albirhiza Bigelow & A. H. Smith
glacialis Redhead et al.
goetzii Hesler & A.H. Smith
marzuolus (Fr.) Bres.
subalpinus A. H. Smith
montanus O.K. Miller
angelesiana A. H. Smith
overholtlsii A. H. Smith & Solheim
angelesianus (A. H. Smith& Hesler) Singer
albipilatus (Peck) Wells & Kempton
occidentalis Wells & Kempton
alboluteus (Ellis & Everh.) Kotl. & Pouzar
leucospongius (Cooke & Harkn.) Bondartsev & Singer
alpina (Tracy & Earle) Brasf.
fulgens (Pers.) Boud.
pathogen on Picea
|Discina perlata (Fr.)
flavidus Kanouse & A.H. Smith
yellow cedar litter:
Callitropsis nootkatensis (D. Don) Oerst.;
syn.: Chamaecyparis nootkatensis (D.
latahense Paden & Tylutki
mexicanum (Ellis & Holw.) Paden & Tylutki
||decomposer Abies, Picea litter
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Just for fun, check out this article which describes mushrooms
actually made out of snow!
- Cornish, V.
- On snow-waves
and snow-drifts of Canada. The Geographical Journal 20:137-173.