Summary:
Also listed in Polypores category. Features include 1) resupinate growth on coniferous and hardwood structural timbers, 2) a whitish to buff to ochraceous gray finely pored surface that appears merulioid, this layer distinct from the thin, soft, buff subiculum, and rhizomorphs present, 3) spores that are broadly elliptic, smooth, dextrinoid, and pale brown, the inner spore layer cyanophilic, 4) a monomitic hyphal system, the hyphae with clamp connections. This species is an important cause of decay in houses and other wooden structures: masses of mycelium in walls and under floors give rise to coarse rhizomorphs that transport water from wet areas to structural wood far removed from the wet area.

Microscopic:
SPORES 10-16 x 5-8 microns, broadly elliptic, rather variable in size and shape, smooth, dextrinoid, pale brown in KOH, spore print rusty brown; BASIDIA 4-spored, 30-60 x 7-9 microns, narrowly clavate; CYSTIDIA and other sterile hymenial elements absent; HYPHAE monomitic, subicular hyphae 2.5-9 microns wide, colorless in KOH, thin-walled, often branched, with simple septa and clamp connections, hyphae of trama 3.5-4.5 microns wide, colorless, parallel, thin-walled, with simple septa and clamp connections, (Gilbertson), SPORES 9-12 x 5-7 microns, ovate, somewhat flattened on one side, smooth, greenish to olive-brown or dark brown, walls 0.7-1 micron thick, in Melzer''s reagent brown with faint blue halo, in lacto-phenol cotton-blue, blue with no colored walls or contents visible, apiculate; BASIDIA 4-spored, 20-25 x 5-6 microns; hymenium simple, composed exclusively of basidia; CYSTIDIA not seen, CONTEXT formed of generative hyphae 2.5-5 microns wide, rather loosely interwoven to parallel-arranged, colorless, when old with yellowish coloring material on surface, more or less parallel with substrate, branching irregularly, with rare clamp connections, (Cooke), SPORES 9.6-13.6(16.8) x 5.6-8.0(8.8) microns, oval to broadly oval, adaxially flattened, smooth, dextrinoid (red-brown), pale yellow brown, rather thin-walled, the wall colorless in lactic-blue with a dark blue zone immediately inside; BASIDIA and CYSTIDIA not found; HYPHAE monomitic, tramal hyphae 3.2-4.8 microns wide, "parallel, closely packed, not readily separating even in squash mounts", colorless, thin-walled, septate with clamp connections, (Ginns(17))

Notes:
Meruliporia incrassata has been found in BC, WA, OR, ID, NB, ON, AL, CA, CT, DC, FL, GA, IL, KY, LA, MI, MS, NC, NE, NY, OK, PA, SC, TN, TX, and VA, (Ginns(5)). It was not yet reported in Europe (Davidson, R.W.(1) 1953).