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Gerronema strombodes

[ Basidiomycota > Agaricales > Marasmiaceae > Gerronema . . . ]

by Michael Kuo

This odd mushroom threw me for a loop several times when I first began to find it, 15 years ago. It appeared on hardwood logs in abundance in late spring and early summer throughout my main collecting areas in central Illinois. The thing was, my collections differed so much that it took me forever to realize I was collecting one species. My first collection of the species represented very mature specimens; they were quite large (up to 10 cm across) and had yellow caps with radiating brownish fibers. Then I collected the species when it was young; these caps were grayish brown and only reached 5 cm across. It was only after I began to find the mushroom in intermediate stages that I realized the brown fibers on mature caps were the result of the cap's expansion; as it grows the densely-packed, innate brown fibers are stretched out and the yellow color underneath them begins to dominate.

Distinguishing features for Gerronema strombodes include the brown-then-yellow cap, the yellow gills that run down the stem, the habitat on the deadwood of hardwoods, and the white spore print. It lacks a distinctive odor, and its microscopic features (see below) are boring.

Judging from collection records at major herbaria, Gerronema strombodes is primarily a denizen of the southeastern states and the southern Midwest, though its range extends northward to New York. It appears to be restricted to the deadwood of oaks and other hardwoods. A similar species, Chrysomphalina chrysophylla, is more widely distributed; it grows on the deadwood of conifers and, under the microscope, features larger spores and lacks clamp connections.

Chrysomphalina strombodes is a former name, as are Omphalia strombodes and Clitocybe strombodes.


Ecology: Saprobic on the deadwood of oaks and other hardwoods; growing gregariously or, more often, in clusters; late spring through fall; apparently limited to the southeastern United States and the lower Midwest, from Ohio to Florida, west to Missouri, northward to New York. The illustrated and described collections are from Illinois and Kentucky.

Cap: 2–11 cm across; planoconvex at first, becoming centrally depressed or shallowly vase-shaped; tacky at first but soon dry; with innate, brown to grayish brown pressed-down fibers that uniformly cover the surface when young, but begin to be stretched out and streaked-looking or finely scaly with age, exposing a yellow to pale yellowish surface underneath; margin not lined, often incurved, becoming wavy with age.

Gills: Running down the stem; distant; pale to dark yellow; short-gills frequent; cross-veined in mature specimens.

Stem: 3–10 cm long; 2–8 mm thick; tapered at base and flared at the apex; dry; bald; white to dull yellow.

Flesh: Thin; whitish to yellowish; unchanging when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH negative to grayish on cap surface; negative on gills.

Spore Print: White.

Microscopic Features: Spores 6–10 x 4–6 µm; ellipsoid, with a fairly prominent apiculus; smooth; hyaline in KOH; inamyloid. Basidia 4-sterigmate. Cheilocystidia not found. Pleurocystidia not found. Lamellar trama gelatinized and poorly defined. Pileipellis a cutis of hyaline, smooth elements 2.5–7.5 µm wide, with exserted bundles of brown-pigmented, swollen, terminal cells 7.5–15 µm wide, smooth, subclavate to clavate, subcapitate, or irregular. Clamp connections present.

REFERENCES: (Berkeley & Montagne, 1856) Singer, 1962. (Saccardo, 1887; Singer, 1964; Moser, 1983; Phillips, 1991/2005; Norvell, Redhead & Ammirati, 1994; Redhead, 2002; Kuo & Methven, 2014; Baroni, 2017; Woehrel & Light, 2017; Elliott & Stephenson, 2018.) Herb. Kuo 05250403, 05280402, 08160603, 07110801, 06281404.

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Gerronema strombodes

Gerronema strombodes

Gerronema strombodes

Gerronema strombodes

Gerronema strombodes

Gerronema strombodes

Gerronema strombodes
Spore print

Gerronema strombodes

Gerronema strombodes

Gerronema strombodes
Clamp connection

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Kuo, M. (2018, October). Gerronema strombodes. Retrieved from the MushroomExpert.Com Web site: