|Major Groups > Gilled Mushrooms > Dark-Spored > Agrocybe & Cyclocybe > Agrocybe firma|
by Michael Kuo
Agrocybe firma, like other species of Agrocybe, features a brown spore print, a convex cap that does not quickly collapse, and, under the microscope, ellipsoid spores with thickened walls and a germ pore at one end. It lacks a partial veil, so there is no ring on the stem. The stem is, however, one of this mushroom's more distinctive features: it features tiny, whitish-then-brown fibrils that are aggregated into vague longitudinal lines. Other distinctive features include the dark brown cap and the fact that Agrocybe firma grows in clusters on the deadwood of hardwoods.
Ecology: Saprobic; growing in small to large clusters (rarely alone) on the deadwood of hardwoods; spring through fall; widely distributed and fairly common east of the Great Plains; very rarely reported from Colorado, California, and the Pacific Northwest; also found in Europe. The illustrated and described collection is from Illinois.
Cap: 3–6.5 cm; convex at first, becoming broadly convex; tacky; bald; dark brown when young, maturing to yellow brown; the margin not lined.
Stem: 6–8 cm long and 0.5–1 cm thick; more or less equal; distinctively longitudinally ridged with fibrils and aggregations of fibrils that are initially whitish but become brown (reminiscent of scabers in the genus Leccinum); ground color medium brown; without a ring; basal mycelium and rhizomorphs prominent, white.
Flesh: White; unchanging when sliced.
Odor and Taste: Mealy.
Spore Print: Dark brown.
Microscopic Features: Spores 6.5–8 x 4–5 µm; more or less ellipsoid; smooth; thick-walled; with a tiny pore; yellow-brown in KOH; collapsed and brownish in Melzer's. Basidia 4-sterigmate. Cheilocystidia 20–35 x 7.5–10 µm; fusiform to widely fusiform or irregular; often with a subcapitate apex; abundant; hyaline in KOH; smooth; thin-walled. Pleurocystidia 25–40 x 12.5–17.5 µm; widely utriform, with a swollen upper section; smooth; thin-walled; hyaline in KOH. Lamellar trama parallel. Pileipellis hymeniform with scattered pileocystidia; elements golden to yellow-brownish in KOH; pileocystidia primarily fusiform, sometimes with a slightly swollen or nearly capitate apex, projecting only slightly beyond the clavate to ob-pyriform elements of the turf. Clamp connections present.
REFERENCES: (Peck, 1902) Singer, 1940. (Saccardo, 1905; Smith, Smith & Weber, 1979; Breitenbach & Kränzlin, 1995; Nauta, 2005; Miller & Miller, 2006; Baroni, 2017; Ryman, 2018; Sturgeon, 2018.) Herb. Kuo 10101202.
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Cite this page as:
Kuo, M. (2020, September). Agrocybe firma. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/agrocybe_firma.html