E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include a hygrophanous gray brown to dark brown bald moist cap, blackening flesh, pale brownish to grayish gills that blacken where bruised, a pale gray fibrillose stem, a rancid-farinaceous odor and taste, and elongate spores. Lyophyllum semitale is "difficult to recognize immediately in nature, since the blackening of the frbs. is noticeable at most in age or when they are left to lie around for a fairly long time", (Breitenbach(3)). It is common in the western mountains of North America, but also found elsewhere in the Pacific Northwest.

Kauffman lists it for OR. There are collections from BC at the Pacific Forestry Centre and the University of British Columbia. There is a collection by T. O''Dell from WA at Oregon State University. Breitenbach(3) illustrate it from Switzerland.

Cap:
(3)4-10cm across, convex to expanded-umbonate; stains dark gray to black eventually where injured; bald, opaque when moist, (Smith), 2-5cm across, hemispheric becoming convex, "margin incurved for a long time, acute"; "hygrophanous, beige-brown when moist, gray-beige when dry"; "smooth, dull, somewhat butyraceous", (Breitenbach), 2.5-8cm across, convex to depressed; hygrophanous, gray brown to dark bister brown when moist, drying gray; bald, translucent-striate at margin, (Hansen), 5-7cm across, brown-black, drying gray-blackish; moist, (Moser), fuliginous; margin translucent-striate, (Clemencon(1))

Flesh:
whitish to watery gray-brown, blackening, (Breitenbach), thin (Hansen)

Gills:
adnate to somewhat decurrent, close; gray at first, "staining yellowish then bluish and finally black", (Smith), "broadly adnate to slightly decurrent", 65-72 reaching stem, broad, 3 subgills between neighboring gills; cream, blackening after several hours; edges smooth, (Breitenbach), pale brownish to grayish, blackening where bruised, (Hansen), pale gray becoming black-spotted, blackening when pressed, (Moser), pallid or grayish (Clemencon(1))

Stem:
6-10cm x 0.9-1.5cm, pale gray; longitudinally striate and/or fibrillose, (Smith), 4-6cm x 0.8-1.5cm, cylindric, at times somewhat widened toward base or also slightly fusiform [spindle-shaped], "solid, pithy, corticate"; white becoming dingy ocherish, blackening when old; longitudinally fibrillose, (Breitenbach), 4-9cm x 0.3-1.5cm, cylindric, soon hollow; whitish then grayish; fibrillose, base with white tomentum, (Hansen), 5-9cm x 0.8-1.5cm, +/- cap-colored; fibrous-cracking, (Moser)

Odor:
farinaceous (Smith), slightly unpleasant, somewhat rancid, (Breitenbach), rancid (Moser)

Taste:
farinaceous (Smith), mild, somewhat unpleasant, (Breitenbach), rancid (Moser)

Microscopic spores:
spores 7-9 x 4-4.5 microns, smooth; clamp connections present, (Smith), spores 6.5-8.6 x 3.2-4.5 microns, narrowly elliptic, smooth, iodine negative, some with droplets; basidia 4-spored, 23-30 x 6-8 microns, clavate, with siderophilic granules, with basal clamp connection; pleurocystidia and cheilocystidia not seen; cap cuticle of +/- parallel hyphae 2.5-4.5 microns wide, "occasional hyphal ends somewhat exserted", septa with clamp connections, (Breitenbach), spores 6.5-9.5 x 3.5-5 microns, elliptic with attenuated base and suprahilar flattening or depression (illustrated), (Hansen), 8-9 x 4-4.5 microns, "spindly-elliptical", (Moser), spores predominantly uninucleate; gelatinous layer of the cap cuticle absent or under 10 microns thick, hyphae 2-4 microns thick, (Clemencon(1)), spores 6.7-9.3 x 3.3-5.0 microns, "inequilateral with well marked supra-apicular depression", base of spore attenuated, pointed when juvenile, rounded at maturity, uninucleate, rarely binucleate, smooth, inamyloid, strongly cyanophilic and siderophilic; basidia 4-spored, 30-34 x 6-8 microns, with basal clamp connection, with abundant siderophilic granules; marginal cells on gills infrequent, small and easily overlooked, scattered, 10-16 x 1.5-4 microns, cylindric to fusoid, (Clemencon(2))

Spore deposit:
white according to literature (Breitenbach)