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Agaricus porphyrocephalus

[ Basidiomycota > Agaricales > Agaricaceae > Agaricus . . . ]

by Michael Kuo

Agaricus porphyrocephalus is a brownish, fibrillose version of "Agaricus campestris," known from lawns and meadows in eastern North America. It features gills that are pink before turning brown, non-staining flesh, a flimsy ring, and relatively small spores. Despite appearances, however, Agaricus porphyrocephalus is not particularly closely related to species in the campestris group; its ITS sequences clearly separate it.

A white variety, Agaricus porphyrocephalus var. pallidus, is very similar in appearance to the campestris group species, and is best separated from them on the basis of its smaller spores. I have collected the two varieties growing within a few yards of each other.


Ecology: Saprobic; growing alone, scattered, or gregariously in meadows, fields, lawns, and grassy areas; fall; midwestern and eastern North America. The illustrated and described collections are from Illinois and New Jersey.

Cap: 4–9 cm; convex, becoming broadly convex; dry; whitish to brownish underneath brown to grayish brown fibrils and scales; the young margin often adorned with hanging whitish remnants of the partial veil.

Gills: Free from the stem; crowded; short-gills frequent; whitish in buttons but soon pink, then maturing to dark brown; covered with a thin white partial veil when in the button stage.

Stem: 3–6 cm long; 1–1.5 cm thick; more or less equal above a slightly tapered base; with a quickly collapsing whitish ring; whitish to brownish; bald or finely fibrillose.

Flesh: Whitish; not changing when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH negative on cap surface.

Spore Print: Dark brown.

Microscopic Features: Spores: 5.5–6.5 x 3.5–4.5 µm; ellipsoid; smooth; thick-walled; brown in KOH. Basidia 4-sterigmate. Pleurocystidia not found. Cheilocystidia not found. Pileipellis a cutis; elements 5–10 µm wide, smooth, hyaline to yellowish in KOH.

REFERENCES: F.H. Møller, 1952. (Moser, 1978; Weber & Smith, 1985; Phillips, 1991/2005; Hansen & Knudsen, 1992; Nauta, 2001; McNeil, 2006; Kuo & Methven, 2014; Kerrigan, 2016.) Herb. Kuo 10030503, 10101515.

This site contains no information about the edibility or toxicity of mushrooms.


Agaricus porphyrocephalus

Agaricus porphyrocephalus

Agaricus porphyrocephalus

Agaricus porphyrocephalus

Agaricus porphyrocephalus

Agaricus porphyrocephalus

Agaricus porphyrocephalus

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Kuo, M. (2018, April). Agaricus porphyrocephalus. Retrieved from the MushroomExpert.Com Web site: