somewhat similar to the common Ganoderma applanatum but with larger spores and yellow pore surface; description derived from Gilbertson(1); found in CA (Gilbertson), BC (Brenda Callan)
up to 20cm x 10cm x 5cm, stemless, semicircular, flattened horizontally to hoof-shaped, cap surface "finely tomentose and yellowish at the growing margin, quickly becoming crustose" with a hard, horny crust up to 0.1cm thick; pale vinaceous to grayish brown; shallowly to deeply sulcate (grooved) and faintly zoned
up to 4cm thick, firm-fibrous; dark purplish brown; concentrically zonate
4-5 per mm, rounded, with very thick entire walls; "with a bright yellowish cast, bruising dark brown, the yellowish cast remaining on dried specimens"; tube layer "purplish brown, sharply differentiated from the context, tubes whitish within, up to 1.5cm thick"
spores 11-12 x 7-8 microns, broadly elliptic, inamyloid, brown in KOH, with a truncate apex and an apical germ pore, wall two-layered with interwall pillars; basidia 4-spored, about 23-11 microns, "collapsed and difficult to discern in type specimen, apparently broadly clavate with a sharply narrowed base"; cystidia absent; hyphal system trimitic: context generative hyphae 2.5-3.5 microns wide, obscure, colorless, thin-walled, with clamp connections, context skeletal hyphae 2-10 microns wide, pale brown in KOH, thick-walled, nonseptate, with occasional branching, context binding hyphae "rare to apparently absent in crushed mounts of context tissue", trama generative and skeletal hyphae similar, trama binding hyphae 2-5.5 microns wide, colorless to pale brown, "thick-walled, nonseptate, much branched", "often dendritically branched with tapering, pointed tips"