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Agaricus smithii

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

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

by Michael Kuo

Known from the Pacific Northwest and northern California, Agaricus smithii is like a cross between Agaricus augustus and Agaricus silvicola. It has the almondy odor and tawny, fiber-covered cap of Agaricus augustus, but also demonstrates the abruptly swollen stem base of forms of Agaricus silvicola that used to go under the name "Agaricus abruptibulbus."


Ecology: Saprobic; growing alone, scattered, or gregariously under conifers; fall and winter; northern California and the Pacific Northwest.

Cap: 8-15 cm; convex to broadly convex or nearly flat; dry; covered with pressed-down fibers that become aggregated into small scales with maturity; orangish, fading to yellowish orange.

Gills: Free from the stem; close; pink becoming grayish, then dark chocolate brown to blackish in maturity; covered when in the button stage with a whitish partial veil that often features orangish "cogs."

Stem: 7-15 cm long; up to 4 cm thick; tapering slightly to apex; abruptly bulbous at the base; with a prominent, skirtlike, whitish ring; whitish to yellowish; smooth or finely hairy.

Flesh: Whitish; not changing when sliced.

Odor and Taste: Strong, reminiscent of almonds.

Chemical Reactions: Cap surface yellow with KOH.

Spore Print: Dark chocolate brown.

Microscopic Features: Spores: 6.5-10 x 4.5-6.5 µ (usually 7.5-8.5 x 5-5.5 µ); elliptical. Cheilocystidia up to 23 x 14 µ; clavate to swollen and irregular.

REFERENCES: Kerrigan, 1985. (Hotson & Stuntz, 1938; Smith, 1940; Kerrigan, 1985; Kerrigan, 1986.)

Kerrigan (1985) named Agaricus smithii to honor legendary mycologist Alexander H. Smith, who collected it in California and Oregon and described it 45 years earlier (as "Agaricus perrarus," a name since synonymized with Agaricus augustus). However, I suspect that Hotson and Stuntz (1938) documented the mushroom (also as "Agaricus perrarus") in Washington even earlier. Smith (1940) correctly points out that the illustration used by Hotson and Stuntz to illustrate Agaricus perrarus does not correspond to their description, since it features a non-swollen stem base--but regardless of the illustration, Hotson and Stuntz fairly clearly describe the same differences between Agaricus augustus and Agaricus perrarus as Smith does two years later--though they also record a difference in the color of the young gills that Smith found to be variable, causing him to "hesitate to use the character as one of more than secondary importance."


Agaricus smithii

Agaricus smithii

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