Kuehneromyces mutabilis, commonly named for the different colors above and below the annulus.
Picture source: Wikipedia.
Agaricus mutabilis Schaeff.
Dryophila mutabilis (Schaeff.) Quél.
Galerina mutabilis (Schaeff.) P.D. Orton
Lepiota caudicina Gray
Pholiota mutabilis (Schaeff.) P. Kumm.
Brown Stew Fungus
(Adapted from Overholts, 1927)
Cap: 3-6 cm diameter; convex to plane; cinnamon/tan when moist, paler when dry, ochraceous-buff when dry, hygrophanous, glabrous.
Gills: adnate or slightly decurrent, medium-close, 2-4 mm broad, pallid then cinnamon.
Veil: forming a white or dark, superior, evanescent or persistent annulus.
Stem: 3-8 cm tall, 3-5 mm diameter, central, equal, concolorous with the cap above the ring; scaly below the ring, pruinose above, stuffed then hollow.
Spores: reddish ochre, ovoid or elliptic, slightly truncate at one end, smooth, 6-7.5 x 4-5 µm.
Habitat: on stumps and logs.
Edibility: Edible, although not recommended due to similar appearance to poisonous species Galerina marginata.
A long-term Finnish study on the occurrence of some common edible macromycetes describes how K. mutabilis was found at the same tree stumps for 13 years, suggesting an impressive mycelial longevity (Hintikka 1993).
The title of Mentel and associates' paper (1994) suggests that the two-toned pholiota has some anti-viral activity against influenza virus. I'll let you know more details once I get a hold of the paper.
Polysaccharides extracted from the mycelial culture of K. mutabilis and administered intraperitoneally into white mice at a dosage of 300 mg/kg inhibited the growth of Sarcoma 180 and Ehrlich solid cancers by 100% and 90%, respectively (Ohtsuka et al., 1973).
Ohtsuka S, Ueno S, Yoshikumi C, Hirose F, Ohmura Y, Wada T, Fujii T, Takahashi E.
Polysaccharides having an anticarcinogenic effect and a method of producing them from species of Basidiomycetes.
UK Patent 1331513, 26 September 1973.
Last modified: 13-Aug-2008