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Gymnopus alkalivirens

[ Basidiomycetes > Agaricales > Marasmiaceae > Gymnopus . . . ]

by Michael Kuo

This small, dark brown saprobe appears in northern and montane areas of North America, and can be recognized quickly if a drop of KOH or ammonia is applied to its cap, producing a green color change. But without the chemical test . . . well, you're looking at a little brown mushroom with a white spore print and no distinctive odor or taste. In short, you may need to unpack your microscope.

Collybia alkalivirens is a synonym.


Ecology: Saprobic; growing alone, scattered, gregariously, or in clusters on soil, leaf and needle litter, woody debris, and among mosses or ferns; found in hardwood, conifer, and mixed forests; summer and fall; apparently widely distributed in northern North America, the Appalachians, and the Rocky Mountains.

Cap: 1-4.5 cm; convex, becoming broadly convex or nearly flat, with a low central bump; greasy; bald; sometimes becoming somewhat wrinkled; dark brown to dark purplish brown, developing a pale margin and eventually fading to cinnamon or buff overall; the margin sometimes becoming lined.

Gills: Attached to the stem or nearly free from it; close; medium brown to pale brownish.

Stem: 3-8 cm long; up to about 5 mm thick; more or less equal, or with a slightly swollen base; dry; bald; colored like the cap; with brownish fuzz near the base.

Flesh: Whitish to brownish; thin.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia or KOH promptly green on all surfaces.

Spore Print: White.

Microscopic Features: Spores: 5-8 x 2.5-4 µ; smooth; lacrymoid to elliptical; inamyloid. Pleurocystidia absent. Cheilocystidia scattered; cylindric to subclavate; sometimes somewhat lobed or with projections; to about 70 µ long. Pileipellis a cutis of branched elements 3-5 µ wide; greenish in KOH; sometimes encrusted with brown pigment. Hyphae of the gill, cap, and stem trama encrusted with scattered brown granules.

REFERENCES: (Singer, 1948) Halling, 1997. (Smith, Smith & Weber, 1979; Halling, 1981; Halling, 1983; Phillips, 1991/2005; Lincoff, 1992; Halling, 2004.) Herb. Kuo 08041001.

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


Gymnopus alkalivirens

Gymnopus alkalivirens

Gymnopus alkalivirens

Gymnopus alkalivirens

Gymnopus alkalivirens

Gymnopus alkalivirens

Gymnopus alkalivirens
Brown pigment granules

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Kuo, M. (2013, February). Gymnopus alkalivirens. Retrieved from the MushroomExpert.Com Web site: