Meddn Soc. Fauna Flora Fenn. 5: 38. 1879.
Common Name: none
Synonym: Polyporus adusta Willd.:Fr.
Fruitbody annual, effused-reflexed, sessile, forming overlapping thin, leathery brackets, 2-8 cm in length x 2-4.5 cm in width, sometimes incorporating twigs and debris; upper surface tomentose to velvety, often uneven, faintly zoned in shades of tan, medium brown, and grey; margin irregular to occasionally lobed, whitish when young; context 1-3 mm thick, tough, leathery, buff-colored, unchanging, lacking a black line above the tube layer; hymenium finely pored (use hand lens), 5-7 per mm, round to oval, grey to blackish in age, darkening where injured; tube layer 0.5-1 mm thick; odor and taste fungal to slightly astringent.
Spores 4-5.5 x 2.0-2.5 µm, ellipsoid, smooth, hyaline, inamyloid; hilar appendage inconspicuous; spore deposit not observed.
Fruiting in overlapping rows on stumps and logs of hardwoods, e.g. Alnus (alders), Quercus (oaks), and Aesculus (horse chestnut), rarely on conifer wood; appearing after fall rains into mid-winter; uncommon.
Inedible; tough and leathery.
Bjerkandera adusta is a seldom collected leathery bracket fungus that can be confused with the turkey tail fungus, Trametes versicolor. Like the turkey tail, the brackets of Bjerkandera adusta are tomentose-velvety and zonate, but the banding is muted, in shades of brown and grey, while those of Trametes versicolor are distinctly zoned and often multicolored (white, brown, rusty brown, yellow, blue and black). In the field Bjerkandera adusta can easily be distinguished from Trametes versicolor by a greyish to blackish (not white) finely pored hymenial surface. A closely related species, Bjerkandera fumosa differs only in slightly larger, thicker fruitbodies, the pore surface not as dark, and the presence of a black line separating the tube layer from the context. Another bracket fungus, Cerrena unicolor, uncommon in California, has a cap similar to Bjerkandera adusta, also occurs on hardwoods, but has a two layered context with a blackish line separating the layers. More significantly, the pores, although greyish, become labyrinthoid to dentate in age. Less likely to be confused with Bjerkandera adusta are Trametes betulina, until recently known as Lenzites betulina, which has a hymenium of gill-like plates, and Stereum species which have a smooth hymenial surface.
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