Summary:
Section Pluteus. The presence of this group in the Pacific Northwest has not been well established. Diagnostic characters are 1) small size, 2) cap color gray-brown, when old drab or more bluish gray or greenish gray, 3) cap surface dry and minutely scabrous over darker disc, often with minute appressed fine scales toward margin, 4) free close gills, 5) a stem developing bluish, bluish gray or bluish green stains over time, 6) a pinkish brown spore deposit, 7) hooked pleurocystidia of the P. cervinus type, and 8) abundant clamp connections on the hyphae of the cap cuticle. |The group designation is used because Justo(4) say that the species has not been confirmed for North America. It includes here those species in the Pluteus salicinus clade of Justo(4) which show green or blue color. Justo(4) elevates Pluteus salicinus var. americanus to species status as Pluteus americanus (P. Banerjee & Sundb.) Justo, E.F. Malysheva & Minnis, but say that is not recorded from western North America. The Pluteus salicinus group is therefore questionable for the Pacific Northwest. |Pluteus salicinus var. achloes lacks blue-green staining and is occasionally hygrophanous, the type variety according to Banerjee(3) being non-hygrophanous. |Pluteus salicinus var. americanus has a bald hygrophanous cap with a translucent-striate margin when moist, and pleurocystidia with compound apical ornamentation (almost never found in the other 2 varieties) - also the cap dries dark bluish - "fuscous" (Ridgway(1)) but this character is present to some extent in other varieties of P. salicinus, (Banerjee(3)). |In the Pluteus salicinus clade as described by Justo(4), there are two other species - blue-green colors are specifically mentioned for one of them called Pluteus saupei Justo and Minnis from Illinois. According to Justo(5), it differs from P. salicinus "in the poorly developed hooks on the pleurocystidia and the morphology of the cheilocystidia". Cheilocystidia of P. saupei are 45-85 x 9.5-19.5 microns, "mostly lageniform with elongated apices, some fusiform or ovoid", colorless, "thin-walled, crowded, forming a well-developed strip".

Cap:
2-5cm across, obtuse to bell-shaped when young, often becoming and remaining broadly convex to flat, rarely umbonate; not hygrophanous (but var. achloes is occasionally hygrophanous), color varying from near gray brown, "Hay's brown" to nearly "fuscous" at first and when old "drab" or a more bluish gray; typically dry and minutely scabrous over disc and with minute appressed squamules [fine scales] toward margin, margin even, translucent-striate, (Banerjee), 3-7cm across, convex to broadly convex, expanding when old to broadly convex to flat; gray to gray greenish to bluish gray, darker toward disc; smooth to finely scaly near center, (Stamets), up to 8cm across, sometimes with fine brownish, grayish or very pale erect scales in center, tinged greenish or quite dark green at least in the center; smooth to fibrillose, (Courtecuisse)

Flesh:
thin; dingy, gray to watery, (Banerjee), in stem [at least] often bruising bluish where injured, especially near base, (Stamets)

Gills:
free and fairly remote from stem, close, 1-2 tiers of subgills, gills moderately broad; whitish when young, pink when old, edges colored as faces; edges smooth to fimbriate, (Banerjee), free; pallid to cream, soon pinkish to salmon, (Stamets), somewhat notched; white, (Courtecuisse)

Stem:
2.5-7cm x 0.3-0.4(0.7)cm at top, equal or nearly so, hollow, somewhat fragile; whitish "but developing bluish, bluish gray or bluish green stains over lower part or at base"; bald, scant persistent mycelium at stem base, (Banerjee), 4-10cm x 0.2-0.6cm, white to grayish green, often with blue tones, base of stem bruising bluish, (Stamets), up to 10cm long and 0.8cm wide, white to faintly greenish below, bald to fibrillose, (Courtecuisse)

Veil:
[absent]

Odor:
"mild to rarely disagreeable (acid-like)", (Banerjee), none (Courtecuisse), faintly radish-like (Breitenbach)

Taste:
like Clitocybe nebularis (Banerjee quoting Smith), mild (Breitenbach)

Microscopic spores:
spores 7-8.4(10) x 5-6 microns, elliptic to oval, smooth, nearly colorless; basidia 4-spored, 30-35 x 7-8 microns; pleurocystidia very abundant, occasionally infrequent, (40)50-70(88) x (11)15-18 microns, "fusoid-ventricose with a crown of 3-5 acute or obtuse and uniformly to irregularly arranged horns around the apex", the distal wall (from ventricose part to tip) apparently quite rigid but not very thick (1.2-1.4 microns thick), cheilocystidia in fascicles, (20)35-50(85) x (9)15-21 microns, clavate to narrowly vesiculose, rarely similar to pleurocystidia in shape, colorless; cap cuticle composed of radial hyphae, end cells of some cystidioid but appressed, others narrowly cylindric, 90-120 x 9-20 microns, content gray-brown; clamp connections profuse on cap cuticle hyphae, (Banerjee), spores 7-8.5 x 5-6 microns, elliptic to oval, smooth; pleurocystidia "fusiform to lageniform, with or without hooked ends", 58-90 x 10-22 microns with apex 5-10 microns wide, cheilocystidia 30-85 x 8-20 microns, pear-shaped to clavate to cylindric or slightly lageniform, (Stamets)

Spore deposit:
pinkish (Stamets)

Notes:
Banerjee(3) examined collections of P. salicinus var. salicinus from MI, ON, CO, IL, NC, Switzerland. They cite 2 collections also from Washington, but both of them appear in the actual herbarium notes to come from Michigan. There are collections of var. achloes cited from Washington and MI but again the detailed herbarium notes make it evident that the Washington collections are actually from Michigan. They cite collections of var. americanus from MI and NC. |There are five other collections at the University of Washington designated as Pluteus salicinus. Two have no notes, one is Pluteus salicinus? in the notes, one is Pluteus (salicinus type...), and one is Pluteus (salicinus group...). The last mentions a blue-gray green stain halfway up the stipe. |Two collections from BC labeled as this species are deposited at the University of British Columbia, one of them from 2014. It is not known how these were differentiated from other blue-staining Pluteus species. |Justo(4) gives the range of Pluteus salicinus as widespread in western Europe and eastward into Siberia as far as the Novosibirsk region, and comments that all other collection in this species complex from the eastern parts of Eurasia and from North America have turned out to be different species. |For Pluteus americanus, Justo(4) give the distribution in Eurasia as known with certainty only from Russian Far East, and in North America as known with certainty from IL, MI, and NY, probably more widespread than that in the Eastern parts of North America, but not recorded from western North America. P. saupei was described from IL. |In California, Siegel(2) say that there are at least three species with blue discoloration on the stem, a species in the Pluteus salicinus group growing primarily on wood chips in urban areas, a species in the Pluteus nanus group growing on wood chips in urban areas, and Pluteus phaeocyanopus (cap cuticle different) on woody debris of Tanoak and live oak.

EDIBILITY

weakly to moderately hallucinogenic, 0.05-0.35% psilocybin, 0-0.11% psilocin, 0.008% baeocystin, edibility unknown, (Stamets)