Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Pluteaceae
Genus: Pluteus

Cap: 2 — 5(8) cm in diameter, convex becoming broadly convex to plane, silver-gray to brownish-gray, often with blue or greenish tint in age, smooth, with tiny scales near the center, darker at the margin, slightly translucent-striate when moist, unlined cap margin, flesh white with a grayish tinge, thin to moderate. Cap skin fibrous.

Gills: Crowded, broad, free, at first white, becoming pink-flesh colored; ventricose. Edges discoloring or bruising grayish.

Stipe: 3 — 5(10) long, 0.2 — 0.6 cm thick, more or less equal or slightly swollen at the base, flesh white with grayish-green to bluish-green tones, especially near the base. Ring absent. Firm, full or stuffed.

Taste: Unpleasant, indefinite or somewhat raphanoid (like radish).

Odor: Unpleasant, indefinite or somewhat raphanoid.

Flesh: Insubstantial; pale.

Spores: pink, smooth, 7 — 8.5 × 5 – 6 µm. Spore print pink-flesh colored to brown-pink.

Microscopic features: Pleurocystidia fusiform with slightly thickened walls 50 — 70 × 11 — 18 µm; with 3 — 5 horn-like projections.

http://www.mushroomexpert.com/pluteus_salicinus.html

Widely distributed across Europe and the United States.

Solitary or gregarious, Saprobic on decaying hardwood logs and debris, in damp forests on flood-plains.
Often found on alder and willow. It is always found growing on wood. Summer-fall

Pluteus cervinus and Pluteus magnus may be misidentified as Pluteus salicinus.

Contains the psychoactive alkaloids, psilocybin and psilocin. Some people use mushrooms with these alkaloids in them to have spiritual or healing experiences.

Stamets, Paul (1996). Psilocybin Mushrooms of the World. Berkeley: Ten Speed Press. ISBN 0-9610798-0-0.

Ohenoja E, Jokiranta J, Mäkinen T, Kaikkonen A, M. Airaksinen MM. (1987). The occurrence of psilocybin and psilocin in Finnish fungi. Journal of Natural Products 50(4): 741-744.

Christiansen AL, Rasmussen KE, Hoiland K. (1984). Detection of psilocybin and psilocin in Norwegian species of Pluteus and Conocybe. Planta Medica 51(4): 341-343.

Kuo, M. (2004, December). Pluteus salicinus. http://www.mushroomexpert.com/pluteus_salicinus.html

Synonyms

Agaricus salicinus
Pluteus Petasatus
Pluteus salicinus var. beryllus

Common names include ‘Knackers Crumpet’ and ‘Willow Shield’.

Several varieties of Pluteus salicinus have been described, including Pluteus salicinus var. achloes, which does not stain blue according to Singer (1956), but does according to Smith, Smith & Weber (1979).