Summary:
Features include a resupinate, woody fruitbody that has small, circular, reddish brown pores, a margin that is yellowish brown at first becoming blackened, flesh that is not zoned, perennial growth on dead wood of Prunus, and microscopic characters including abundant setae. Ginns(28) notes that significantly different spore sizes reported for this species suggests that two species have been labeled P. prunicola. The range given by Gilbertson(1) is 3.5-5 x 2.5-3.5 microns and the range given by Parmasto 2007 is 5.2-6.4 x 3.9-4.6 microns. The description here is derived from Gilbertson(1) except where noted.

Microscopic:
spores 5.2-6.4 x 3.9-4.6 microns (Parmasto 1987 according to Ginns(28)), 3.5-5 x 2.5-3.5 microns, oval to nearly round, smooth, inamyloid, colorless, (Gilbertson(1)); basidia 4-spored, 11-12 x 5-6 microns, without clamp connection at base; setae abundant, mostly ventricose, thick-walled, 15-18 x 5-6.5 microns; context hyphae mostly dark reddish brown in KOH, thick-walled to thin-walled, with rare branching, aseptate, 2.5-4 microns wide, some pale brownish to colorless, thin-walled, with frequent branching, 2-3 microns wide, septa without clamp connections; trama hyphae similar, arrangement of skeletals semiparallel, (Gilbertson(1)), generative hyphae 2-3 microns wide, thin-walled, "hyaline to pale brown", skeletal hyphae 2.5-4.0 microns wide, thin- to thick-walled, dark reddish brown; setae abundant, mostly ventricose, 16-22 x 4.5-6.8 microns, (Ginns(28)).

Notes:
A collection from BC at DAOM in Ottawa was reidentified by Parmasto while studying the Phellinus laevigatus group as Phellinus prunicola, (J. Ginns, pers. comm.). Collections are noted on the range map from NL, MT and PA, but it probably occurs throughout the northern U.S. and southern Canada without being reported, perhaps because of its similarity to Phellinus laevigatus, (Gilbertson).

Synonyms and Alternate Names:
Cheilymenia coprinaria (Cooke) Boud.
Patella coprinaria (Cooke) Seaver