Polyporus Brumalis

This small, dark brown polypore distinguishes itself from similar species by having a stem which does not become black, a smooth (rather than hairy) cap margin, and tiny circular pores. It fruits on the deadwood of hardwoods, and has a special affinity for birch. The tough fruiting bodies are persistent and can be found year-round, but it tends to come up fresh in fall and spring.
Cap: 2-8 cm; broadly convex with a tucked-under margin at first; becoming flat, or shallowly depressed; round in outline; dry; bald or very finely hairy; dark yellowish brown to dark brown.

Pore Surface: Running slightly down the stem; white; not bruising; with 2-3 round pores per mm; tubes to 3 mm deep.

Stem: Central or somewhat off-center; 2-4 cm long; 2-5 mm wide; equal; dry; bald or finely hairy; whitish to grayish or pale brownish; tough.

Flesh: Whitish; thin; very tough.
Spore Print: White.

Microscopic Features: Spores 6-7 x 1-1.5 µ; cylindric; smooth; hyaline in KOH. Hymenial cystidia not found. Hyphal system dimitic. Clamp connections present.