E-Flora BC: Electronic Atlas of the Flora of British Columbia

Paxillus involutus (Batsch) Fr.
inrolled pax

Species account author: Ian Gibson.
Extracted from Matchmaker: Mushrooms of the Pacific Northwest.

Introduction to the Macrofungi

© Michael Beug  Email the photographer   (Photo ID #17674)

E-Flora BC Static Map
Distribution of Paxillus involutus
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Species Information

Features include staining of all parts brown to reddish brown when handled or when old, dingy brownish cap that is inrolled for a long time, decurrent gills that are forked or veined near stem, stem shorter than cap width, and frequent association with birch. Paxillus involutus is commonly found in the Pacific Northwest. There are collections from BC at the University of British Columbia, and collections at the University of Washington from WA, OR, CA, and also NB, ON, AK, CO, MI, and NY.
4-15(20)cm across, at first broadly convex with strongly inrolled margin, then flat or centrally depressed with margin eventually unfurled; brown to dingy yellow-brown, olive-brown, or dingy reddish brown, often with darker brown stains; "viscid when moist but otherwise dry", "smooth or with soft matted hairs that wear away", sometimes cracked (areolate) when old, "margin often slightly velvety or obscurely ribbed", (Arora), 4-15cm across, convex becoming flat with a central depression when old, margin deeply inrolled at first, remaining inrolled until a late age; cap "light reddish brown, tinged with olive, to yellow-brown"; dry, "covered with matted, soft hairs, sometimes obscurely zoned or spotted", (Miller)
thick, firm; "pale buff to yellowish, but usually staining reddish to brown when cut", (Arora), thick; dingy yellowish bruising brownish, (Miller)
usually decurrent, close or crowded, often forking and/or forming pores (anastomosing) near stem; "pallid to pale yellowish becoming dingy yellow to olive, brownish, or yellow-brown", staining dark brown or reddish brown when bruised or when old, (Arora), decurrent, crowded, broad, sometimes anastomosing and interveined near stem; yellowish olive bruising brown, (Miller)
2-7(10)cm x 0.5-4cm, "usually shorter than width of mature cap, equal or tapered at either end, central to somewhat off-center, solid, firm"; cap-colored or paler, "often with dingy reddish to dark brown stains"; dry, smooth, (Arora), 4-10cm x 1.4-2cm, equal or widening downward, central; "yellowish brown, streaked or stained darker brown"; dry, bald, (Miller)
absent (Arora)
mushroomy (Phillips), pleasantly aromatic, fruity, (Breitenbach), slightly acid-fruity (Lincoff(1)), pleasant (Miller)
acid (Phillips), mild, sourish, fungoid, sometimes astringent, (Breitenbach), mild to unpleasant (Miller)
Microscopic spores:
spores 7-10 x 4-6 microns, elliptic, smooth, (Arora), spores 7-9 x 4-6 microns, elliptic, smooth, yellowish to dextrinoid in Melzer's reagent, thick-walled, (Miller), spores 6.6-10.2 x 5.1-6.7 microns, elliptic-oval, smooth, iodine-negative; basidia 4-spored, 30-48 x 8.5-10.5 microns, clavate, with basal clamp connection; pleurocystidia and cheilocystidia 40-90 x 8-15 microns, fusiform, with brown contents; clamp connections mentioned for basidia and cap cuticle, (Breitenbach)
Spore deposit:
brown to yellow-brown, (Arora), rust-brown (Breitenbach), clay-brown to yellowish brown (Miller)

Habitat / Range

usually scattered to densely gregarious on ground in woods, around the edges of bogs, and in treed parks or lawns, often with birch, (Arora), "occurs in natural forest in our region but is not common there", much more abundant in parks and landscaped areas where typically associated with birch, (Trudell), single or several, "on ground under conifer or hardwood forest including aspen and birch", summer and fall (Miller), spring, summer, fall, (Bacon)

Taxonomic and Nomenclatural Links

Genetic information (NCBI Taxonomy Database)
Taxonomic Information from the World Flora Online
Index Fungorium
Taxonomic reference: Epicrisis systematis mycologici (Uppsala): 317 (1838)

Additional Range and Status Information Links


poisonous: can cause hemolysis and kidney failure (Arora), severe gastrointestinal upset can result (Miller)

Additional Photo Sources

Related Databases

Species References

Arora(1)*, Phillips(1)*, Lincoff(2)*, Lincoff(1)*, Miller(14)*, Trudell(4)*, Ammirati(1)*, Schalkwijk-Barendsen(1)*, Kibby(1)*, Courtecuisse(1)*, Bessette(2)*, Barron(1)*, Breitenbach(3), Bacon(1)*, AroraPocket*, Buczacki(1)*

References for the fungi

General References