Summary:
Features include 1) resupinate growth on bark and wood of coniferous logs, 2) a yellowish fruitbody that is fleshy-membranous, firmly attached, the surface usually turning green to greenish black in KOH, the margin white or colored as the rest of the surface, sometimes reddish brown, usually fringed to fibrillose, the subiculum colored as the spore-bearing area or paler, 3) spores that are narrowly elliptic, smooth, inamyloid, and colorless, 4) abundant cystidia that are tapered or awl-shaped, projecting, smooth or with occasionally granules on apex, and 5) a monomitic hyphal system, the hyphae mostly encrusted with granules that dissolve in KOH, mostly without clamp connections.

Microscopic:
SPORES 4.5-6 x 2-3 microns, narrowly elliptic, smooth, inamyloid, acyanophilic, colorless, thin-walled; BASIDIA 4-spored, 25-45 x 5-6.5 microns, narrowly clavate, colorless, thin-walled, sterigmata 3-5 microns long; CYSTIDIA 40-60 x 4-6.5 microns, tapered to apex or subulate [awl-shaped], (sometimes somewhat flexuous), thin-walled or rarely with thickened walls, "smooth or with scattered granules on apex", projecting 25 microns beyond the hymenium, "mostly aseptate but with occasional secondary septa"; HYPHAE monomitic; SUBHYMENIUM a compact textura intricata-porrecta, "thickening, sometimes more or less layered due to interrupted growth", hyphae 3-4.5 microns wide, thin-walled, colorless, "encrusted with yellow granules that dissolve in KOH", simple-septate, "with frequent and regular branching, often at nearly right angles"; SUBICULUM a textura intricata, hyphae 4-9 microns wide, walls slightly thickened or up to 2 microns thick, colorless with frequent branching in most specimens, "mostly simple-septate, multiple clamp connections rare", "mostly encrusted with fine granules that dissolve in KOH" and often with persistent colorless crystals, (Burdsall), SPORES 4-5 x 2-2.5 microns, smooth, spore collection white; BASIDIA 4-spored; CYSTIDIA numerous in hymenial surface, 4 microns wide at base, "protruding up to 30 microns beyond the basidia", hair-like, not encrusted, tapered to a sharp tip, gloeocystidia absent; IN SECTION 400-700 microns thick, colored like hymenium in thick sections but very thin sections colorless, "somewhat zoned, composed of a very broad hyphal layer bearing a hymenial layer 50-60 microns thick", the hyphae colorless, (Burt), SPORES 4-5 x 2-2.5 microns, narrowly elliptic; BASIDIA 25-45 x 4.5-6 microns; CYSTIDIA abundant, 45-60 x 3-5 microns, projecting, cylindric, thin-walled; hyphae 2-8 microns wide, thin-walled to slightly thick-walled, (Julich), SPORES 4-5.5 x 2-2.5 microns, short-cylindric, smooth, inamyloid, colorless; BASIDIA 4-spored, 5-6 microns wide, clavate; CYSTIDIA abundant, projecting up to 20 microns, 3-8 microns wide, tapering to the tip, thin-walled, not encrusted, often septate; SUBICULAR HYPHAE 3-9 microns wide, thin-walled to thick-walled, "simple-septate, with some simple and double clamp connections, these more numerous in the marginal strands", hyphae loosely arranged in lower subiculum, (Gilbertson)

Notes:
Phanerochaete carnosa has been found in BC, WA, OR, ID, MB, NF, NS, ON, PQ, AK, AZ, CA, CO, MA, ME, MI, MN, MT, NH, NM, NY, SD, and VT, (Ginns). It is common in Rocky Mountain forests (Burt). It also occurs in Russia (Burdsall).