Fomes fomentarius (L. : Fr.) J.J. Kickx.

Syn: Polyporus fomentarius L. : Fr. Profile Group: Basidiomycota, Polyporales

Macroscopic characters	shape	ungulate; sessile
	size	2–15 cm wide
	texture	tough to woody, even when fresh
	pileus	smooth; zonate; hard crust; brownish gray to nearly black
	stipe	N/A
	context	brown; up to 1 cm thick; yellowish brown granular core
	pore surface	brown to grayish brown; concave
	pores	round; 4–5 per mm
	tube layer(s)	stratified; each layer up to 1 cm long
Microscopic characters	hyphal system	trimitic
	clamp connections	present on generative hyphae, but sparse
	sterile elements	none
	basidiospores	cylindric; hyaline; smooth; nonamyloid; 12–18 x 4–7 µm
Habitat characters	substrate/host	living and dead deciduous trees; common on birch and beech
	seasonality	perennial; can be found throughout the year
	type of decay	white mottled heart rot of living trees
	range	North Carolina north to SE Canada, transcontinental to the Pacific Northwest, north to Alaska. Southern limit appears to be in the southern Appalachian Mountains in North Carolina and Tennessee.
Compare with		Fomes fasciatus, a southeastern US species that is applanate, seldom ungulate, with a convex pore surface, and found chiefly on oaks. The ranges of F. fasciatus and F. fomentarius overlap in Tennessee and North Carolina.
References		Overholts, 1953; Gilbertson & Ryvarden, 1986.