Species Fact Sheet
Common Name:
Scientific Name: Amanita armillariiformis Trueblood & D.T. Jenkins
Division: Eumycota
Subdivision: Basidiomycotina
Class: Hymenomycetes
Order: Agaricales
Family: Amanitaceae
Type Locality: Oasis, Malheur Co., Oregon.
Holotype: MICH 6454
Technical Description: Cap 4-10.5(-16) cm wide; thick and convex to plane; margin
initially strongly incurved, smooth, non-striate, appendiculate, with a distinct sterile edge
and prominent, frequent, radial splits at maturity; surface tissue of cap very thin, slightly
gelatinized, not easily separated from underlying tissue, glabrous, dry to very slightly
sticky when moist; dull white to dull pinkish-buff; cap flesh white; universal veil often
absent, but may be present as thin, floccose patches or crusts with a pale, salmon tint.
Gills nearly free or joined to stalk by a fine line; white turning to pale tan at maturity;
edges slightly flocculose. Stalk (3.5-)5-9 cm x 17-24 mm, cylindric or sometimes
expanding slightly toward base, nearly glabrous with fine tufts of white fibrils or scales
below, solid or slightly stuffed; flesh white; basal bulb not wider or only slightly wider
than stalk. Partial Veil (annulus) thin, membranous, white, on upper to mid-portion of
stalk, easily torn, frequently adhering to stalk or cap margin, or disappearing. Universal
Veil remnants on bulb or lower stalk (volva) are concentric rings or random chunks or
patches with a pale salmon tint. Spores 10.0-12.9 x 6.2-8.2 um, elliptic to elongate,
adaxially flattened, thin-walled, hyaline, weakly amyloid, spore print white. Other:
Basidiocarps of Amanita armillariiformis are solitary to gregarious; odor is unpleasant,
sometimes strong and medicinal.
Any mushroom with a universal veil, pallid (very pale colored) gills and white spores is
likely to be an Amanita.
The frequent absence on collected specimens of A. armillariiformis of any remnants of a
universal veil is an unusual feature among Amanita spp. and encourages attention to other
common (but not universal) Amanita features such as close, free gills and presence of a
partial veil. The universal veil is frequently absent in several other Amanita spp., but
most of these are regularly found at wetter, forested sites. While basidiocarps of Amanita
armillariiformis bear a superficial resemblance to those of Armillaria spp. (i.e., robust
stature, thick, convex cap, and annulus present on the upper half of a more or less
cylindrical stalk), Armillaria spp. in general are distinct from Amanita spp. in having
attached gills and lacking a universal veil and its associated volva. Other white-spored,
annulus-bearing genera that might be mistaken for Amanita include Lepiota and
Cystoderma. Species of each of these genera generally lack a universal veil and volva,
and in Cystoderma, gills are generally attached, as well.
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Amanita armillariiformis resembles A. prairiicola in features such as 1) xeric, nonforested habitats, 2) sterile edge on cap margin that is frequently appendiculate, 3)
essentially cylindric stalk with indistinct bulb, 4) medicinal odor (not in all specimens),
and 5) elongate spores (elliptical to elongate in A. armillariiformis). In contrast, caps of
Amanita armillariiformis are typically dull white to pinkish-buff, with pale salmon
universal veil patches, with surface tissue thin, slightly gelatinized, not easily separated
from underlying tissue, and gills pale tan at maturity. Caps of A. prairiicola are typically
pale tan with brownish universal veil patches, with surface tissue membranous and easily
separated from underlying tissue, and gills grayish at maturity.
Life History: Sporocarps present during late March and April through mid-June. One to
several sporocarps per occurrence.
Range, Distribution and Abundance: Known from Owyhee Co., Idaho west to
Malheur Co., Oregon, where four sites are documented between Mitchell Butte and
Willow Springs, about 14-47 miles south of Vale. Also reported from Colorado and
Alberta, Canada.
Habitat Associations: Among sagebrush, mustards, cheat grass, bluegrass, aspen,
Douglas fir and scattered willow, usually in xeric areas on hard ground or in dunes.
Amanita armillariiformis is assumed to be ectomycorrhizal, but Salix may be the only
suitable host regularly present in this habitat.
Threats: The ecology of ectomycorrhizal fungi inhabiting xeric plant communities east
of the Cascades in Oregon and Washington appears to be a much less studied than that of
fungi of the mesic and damper coniferous forests in and west of the Cascades. Threats
that generally apply to this latter group of fungi may not necessarily be transferable to the
former group. Nevertheless, while awaiting the development of more relevant data, it is
reasonable to assume that actions or events that remove host plants and/or reduce cover
of coarse woody debris or other organic nutrient sources may have detrimental effects to
Amanita. Reduction in various ground covers that promote retention of soil moisture
may also adversely effect this fungus.
Conservation Considerations: Revisit documented localities to reconfirm presence and
better define habitat. Monitor known sites to better understand relationship between
sporocarp production and environmental variables. Consider mapping areas with high
potential for suitable habitat. Search for new populations on federal land. Consider
buffering known sites and protecting from wildfire, prescribed burns, vegetation
management projects that would remove potential host plants, and ground-disturbing
activities (e.g., recreational vehicles, grazing) that would reduce moisture-retaining
ground covers. Support research focusing on the ecology of dryland fungi, including the
effects of invasive plant species.
Conservation Rankings and Status:
Global: G2?; Oregon S1
ORNHIC List 3
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Prepared by: Rick Dewey, Deschutes National Forest, March 2009
References
Arora, David. 1979. Mushrooms Demystified - A Comprehensive Guide to the Fleshy
Fungi. Ten Speed Press, Berkeley, California. 959 pp.
Cushman, Kathleen and Rob Huff. 2007. Conservation Assessment for Fungi Included
in Forest Service Regions 5 and 6 Sensitive and BLM California, Oregon and
Washington Special Status Species Programs. R6 USFS and OR/WA BLM Interagency
Special Status/Sensitive Species Program (ISSSSP).
http://www.fs.fed.us/r6/sfpnw/issssp/planning-tools/
Ferriel, Jenifer and Katie Grenier. 2008. Annotated Bibliography of Information
Potentially Pertaining to Management of Rare Fungi on the Special Status Species List
for California, Oregon and Washington. R6 USFS and OR/WA BLM Interagency
Special Status/Sensitive Species Program (ISSSSP).
http://www.fs.fed.us/r6/sfpnw/issssp/planning-tools/
Fogel, Robert. 1994. Report on Fungi from the Columbia Basin Deposited in the
University of Michigan Herbarium. Interior Columbia Basin Ecosystem Management
Project, Science Integration Team - Terrestrial Staff. December 7, 1994. 21 pp. + 5
appendices.
Lindgren, Janet. 1998. Trial key to the species of Amanita in the Pacific Northwest.
Prepared for the Pacific Northwest Key Council. (includes A. armillariiformis)
http://www.svims.ca/council/Amanit.htm
MICH Fungus & Lichen Database Query for Specimen Data.
http://www.herb.lsa.umich.edu/Bioinformatics.htm
Miller, Orson K. Jr., Ellen Trueblood and David T. Jenkins. 1990. Three new species of
Amanita from southwestern Idaho and southeastern Oregon. Mycologia, 82(1), pp. 120128.
Oregon Natural Heritage Information Center. 2007. Rare, threatened and endangered
species of Oregon. Oregon Natural Heritage Information Center, Oregon State
University. Portland. 100pp.
http://oregonstate.edu/ornhic/2007_t&e_book.pdf
USDA Forest Service. 1995. Report on Fungi. Prepared by Michael A. Castellano for
Interior Columbia Basin Ecosystem Management Project.
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