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Agaricus fuscofibrillosus

[ Basidiomycetes > Agaricales > Agaricaceae > Agaricus . . . ]

Taxonomy in Transition: ...  > Agaricales > Lepiotoid Clade (J&V, 1998)

by Michael Kuo

The red staining, silky brown cap, large size, and dedication to Monterey Cypress define this beautiful mushroom, which is reminiscent of several eastern species, including Agaricus haemorrhoidarius and Agaricus silvaticus. Unlike its eastern counterparts, however, Agaricus fuscofibrillosus does not typically become prominently scaly with maturity; its pressed-down fibers tend to remain tightly affixed to the cap surface.


Ecology: Saprobic; growing alone, scattered, or gregariously in piled litter of Monterey Cyprus; sometimes reported under other coastal trees (including Coast Live Oak); fall and winter; on the West Coast.

Cap: 5-13 cm; convex, becoming broadly convex or broadly bell-shaped; dry; covered with brown to reddish brown, pressed-down fibers that usually remain more or less tightly affixed but occasionally aggregate into small scales; shiny.

Gills: Free from the stem; close; pink when young, bruising reddish; later dark chocolate brown to blackish; covered when in the button stage with a whitish to brownish partial veil.

Stem: 6-14 cm long; up to 3 cm thick; more or less equal, or slightly enlarged below; with a prominent, skirtlike, whitish to brownish ring; whitish above the ring and brownish below it; bruising reddish; fairly smooth or finely hairy.

Flesh: White; changing to red when sliced.

Odor and Taste: Odor not distinctive or sweet and fruity; taste similar.

Chemical Reactions: Cap surface negative with KOH.

Spore Print: Dark chocolate brown.

Microscopic Features: Spores: 4.5-7.5 x 3-5 µ; elliptical. Cheilocystidia up to 22 x 7 µ; clavate to cylindric; scattered.

REFERENCES: (Mųller, 1950) Pilįt, 1951. (Arora, 1986; Kerrigan, 1986.)

Further Online Information:

Agaricus fuscofibrillosus at MykoWeb


Agaricus fuscofibrillosus

Agaricus fuscofibrillosus

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Cite this page as:

Kuo, M. (2007, October). Agaricus fuscofibrillosus. Retrieved from the MushroomExpert.Com Web site: