N. Amer. Fl. 10(4): 252. 1924.
Common Name: none
Misapplied name: Inocybe geophylla (Sowerby: Fries) Kummer
Cap 2-4 cm broad, conic, then convex, finally nearly plane in age with a low umbo, the margin tending to split in dry weather; surface moist, innately (silky) fibrillose, white to pallid, often spotted brown in age; flesh thin, pallid, unchanging; odor spermatic; taste indistinct.
Gills adnate to adnexed, moderately broad, close, pallid turning drab light-brown in age.
Stipe 2.5-5.0 cm tall, 0.3-0.6 cm thick, equal to tapering downward, sometimes with a small basal bulb; surface white to pallid, moist, finely tomentose at the apex, appressed fibrillose below; flesh pallid unchanging; veil fibrillose, forming a superior, hairy annular zone, soon disappearing.
Spores 7.5-9 x 4.5-5 µm, elliptical, smooth; spore print brown.
Scattered to gregarious in conifer woods, especially common under pine & Douglas fir (Pseudotsuga menziesii); fruiting from late fall to mid-winter.
Unknown, but the similar I. geophylla is toxic, containing Muscarine.
Inocybe insinuata belongs to a complex of similar species that has historically been recognized as Inocybe geophylla, a European species. The real I. geophylla probably does not occur in California. Inocybe insinuata was described from under pines from Berkeley and is one of the more common species of this complex. Inocybe multifolia is a similar whitish species, known from the Sierra Nevada mountains. A similar but undescribed species is more robust and grows with oaks in coastal California. Inocybe pudica is also similar, but it stains red when bruised. There are a number of other small white mushrooms that it could be confused with I. insinuata, including Alboleptionia sericella, Marasmiellus candidus and some species of Hygrohorus. None, however, have the above combination of characters along with brown spores and a spermatic odor. Inocybe lilacina, also found in our area, is a lilac-colored cousin considered by some mycologists to be a variety of I. geophylla.
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Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Kauffman, C.H. (1924). Inocybe. N. Am. Flora 10(4): 227-260. (Protologue)
Kobayashi, Takahito (2002). The taxonomic studies of the genus Inocybe. Nova Hedwigia Beiheft 124. J. Cramer: Berlin. 246 p.
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