Mycologia 36: 252. 1944.
Common Name: none
Misapplied name: Melanoleuca graminicola
Cap 3.0-9.0 cm broad, convex, in age plane to plano-depressed, sometimes with a low umbo; margin at first incurved, then decurved, occasionally wavy; surface moist, glabrous, grey-brown, streaked with darker fibrils; at maturity the cap fading to greyish-tan; context pale-grey, firm, up to 1.0 cm thick, unchanging, watery-grey just above the lamellae; odor and taste mild.
Gills notched, sometimes with a decurrent tooth, close to crowed, at first greyish-tan, in age ash-grey to dingy-cream; lamellulae in four to five series.
Stipe 3.0-5.0 cm long, 0.5-1.5 cm thick, more or less equal to enlarged at base, stuffed at maturity; surface fibrillose-striate, the fibrils whitish over a greyish-brown background in youth, then darkening and becoming concolorous with the underlying stipe; sparse, white mycelium at stipe base; partial veil absent.
Spres 8.0-10.5 x 5.5-6.5 µm, more or less elliptical in both face-view and profile, finely warted, contents granular, hilar appendage inconspicuous, amyloid; spores white in deposit; pleurocystidia and cheilocystidia absent.
Solitary to scattered under montane conifers; fruiting in the spring near melting snow; common.
This nondescript, montane mushroom is often confused with an unrelated snowbank species, Clitocybe glacialis (=Lyophyllum montanum). Both are greyish to greyish-brown mushrooms which at maturity are remarkably similar. Young specimens, however, are more distinctive. The caps of Clitocybe glacialis have a silvery-grey bloom, a feature lacking in Melanoleuca angelesiana. Additionally, Clitocybe glacialis has a dense mycelial mat at the base of the stipe, while in Melanoleuca angelesiana the mycelium is comparatively sparse. These features become less obvious in age at which time a microscope may be needed to confirm an identification. The spores of Melanoleuca angelesiana are warted and amyloid, while those of Clitocybe glacialis are smooth and inamyloid. Another Melanoleuca sometimes found with M. angelesiana is Melanoleuca evenosa. This is a larger species with a paler grey cap in age. Microscopically it differs from M. angelesiana in having both pleurocystidia and cheilocystidia.
Gillman, L.S. & Miller Jr., O.K. (1977). A study of the boreal, alpine, and arctic species of Melanoleuca. Mycologia 69: 927-951.
Smith, A.H. (1944). New North American Agarics. Mycologia 36: 242-262. (Protologue)