Gymnopus spongiosus

[ Basidiomycetes > Agaricales > Tricholomataceae > Gymnopus . . . ]

by Michael Kuo

Gymnopus spongiosus is a litter-decomposing saprobe found in both hardwood and coniferous forests east of the Great Plains. Distinguishing features include its small size, the soon-pale cap, and the fuzzy reddish brown stem. The stem's fuzziness is sometimes lacking, but by maturity the contrast between the cap and stem colors is usually striking. A drop of ammonia or KOH on the mushroom--especially the stem surface--produces a green (or black) reaction. Microscopic analysis (see the details below) will confirm identification.

Edibility is not known for Gymnopus spongiosus. Do not experiment.

Description:

Ecology: Saprobic; growing alone, scattered, gregariously, or in clusters on forest litter under hardwoods (especially oaks) or conifers; spring, summer and fall (or over winter on the Gulf Coast); eastern North America from Massachusetts to Florida and Missouri.

Cap: 1-3.5 cm, convex with a central bump and an incurved margin when young, becoming broadly convex or flat; dry or greasy; smooth, but becoming slightly wrinkled with age; reddish brown when young and fresh, quickly fading to pinkish tan or pinkish buff.

Gills: Attached to the stem or nearly free from it; close; creamy.

Stem: 2-6 cm long; up to about 4 mm thick at the apex; more or less equal, with an enlarged, spongy bottom portion; dry; usually densely hairy with reddish brown hairs, but sometimes appearing smoooth or merely finely hairy near the base; pale above, reddish brown below.

Flesh: Whitish; thin.

Odor and Taste: Not distinctive.

Chemical Reactions: Ammonia or KOH promptly olive, green, or black on cap and stem surfaces.

Spore Print: White.

Microscopic Features: Spores: 6-10 x 3.5-4 µ; smooth; lacrymoid to elliptical; inamyloid. Pleurocystidia absent. Cheilocystidia up to about 50 µ long; variously shaped; often contorted or with fingerlike projections. Pileipellis a tangled cutis of cylindric elements 3.5-10 µ wide, not encrusted but with yellowish brown internal pigment in KOH.

Collybia spongiosa is a synonym; Marasmius spongiosus is a former name.

REFERENCES: (Berkeley & Curtis, 1849) Halling, 1997. (Saccardo, 1887; Kauffman, 1918; Halling, 1981; Halling, 1983; Lincoff, 1992; Halling, 1996; Halling, 1997; Halling, 2004.) Herb. Kuo 05089502, 05030401, 09270503, 05030604, 04270704, 05100801.

Further Online Information:

Gymnopus spongiosus at Roy Halling's Collybia site

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Cite this page as:

Kuo, M. (2007, April). Gymnopus spongiosus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/gymnopus_spongiosus.html