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Species Information
Summary: Gymnopilus picreus is distinguished (Hesler) by color, a finely scaly cap [although Moser says bald, and Bessette smooth then scurfy], narrow rusty-staining gills, an umber to fulvous stem with a white powdery appearance, absence of a veil, caulocystidia in tufts or palisades, and pileocystidia of two general types (as scattered terminal elements and as mounds). Other features include a cinnamon brown to dark red-brown, moist cap, thin cap-colored flesh, adnate to decurrent, close to crowded gills that are yellow when young, a mild to bitter taste, and growth on wood.
Hesler examined material from WA, OR, ID, ON, QC, CA, ME, MI, NY, TN, VT, and Sweden. There is a collection from BC by P. Kroeger at Pacific Forestry Centre and several from BC by O. Ceska at the University of British Columbia. A collection from Finland was used by Guzman-Davalos(2).
Cap: 1-2(5)cm across, convex to bell-shaped - convex, then expanded; hygrophanous, rufous to baybrown-cinnamon [sic]; moist, non-viscid, scurfy, disc subsquamulose [somewhat fine-scaly], rarely rimulose-papillate, (Hesler), 2-4(6)cm across, convex; cinnamon-brown to dark red-brown, margin sometimes lighter, dries yellow-brown to yellow; bald, (Moser)
Flesh: thin, colored as cap, (Hesler)
Gills: "adnate to decurrent, sometimes seceding", close, narrow; "yellow to dull ochraceous, then ferruginous, sometimes staining rusty", (Hesler), crowded, gold-yellow, yellow, (Moser), "bright yellow when young, becoming ochraceous and sometimes staining rusty", (Bessette)
Stem: 5-8cm x 0.2-0.5cm, widening slightly downward, hollow, straight; "umber to fulvous, darkening from the base up"; white-pulverulent [white-powdery] when young, glabrescent [becoming bald], (Hesler), 1.2-5.5cm x 0.2-0.6cm, yellow-brown to red-brown, sometimes fairly dark; "young white-frosted, lower bald", (Moser)
Veil: none (Hesler)
Odor: not distinctive (Bessette)
Taste: mild or bitterish, (Hesler), not distinctive or slightly bitter (Bessette)
Microscopic spores: spores 7-9(9.5) x 4.5-5.5(6) microns, elliptic to nearly oval in face view, slightly inequilateral in side view, verruculose [finely warty], ferruginous in KOH, dextrinoid, no germ pore; basidia 2-4-spored, 23-28 x 5-6 microns; pleurocystidia 27-35 x 6-8 microns, ventricose, cheilocystidia 23-33 x 4-7 microns, "ventricose, capitate or non-capitate, at times with a brown pigment"; gill trama subparallel, hyphae 3-5 microns wide, subhymenium not distinctive; cap trama radial, cap cuticle "of radially disposed, repent, brown, incrusted hyphae, at times more or less erect, the terminal elements as pileocystidia" measuring 25-45(76) x 6-20 microns, clavate, "and at intervals the surface with mounds of brown, clavate pileocystidia" measuring 24-32 x 5-9 microns; caulocystidia 30-62 x 5-17 microns, "flask-shaped, capitate, scattered, or in tufts, or forming a turf"; cap and gill trama dark brown in KOH, reddish brown in Melzer''s reagent; yellow pigment, soluble in KOH, present in gill trama; clamp connections present, (Hesler), spores 8-10 x 5-6 microns, (Moser)
Spore deposit: ochraceous orange (Bessette)
Habitat / Range
on conifer wood and sometimes on hardwood, (Hesler), "scattered or in groups on decaying logs and stumps in mixed woods", July to October, (Bessette), summer, fall
Similar Species
Gymnopilus sapineus has a yellow veil, (Hesler). Gymnopilus liquiritiae has a bald tawny cap that is often larger, (Hesler). Gymnopilus bellulus has smaller spores and generally smaller size. Gymnopilus oregonensis has a bald cap, broad gills, an equal stem, and no pileocystidia.
