The Genus Inocybe  

[ Basidiomycetes > Agaricales > Cortinariaceae . . . ]

by Michael Kuo

So I'm sitting at the collection tables after a day of fungus hunting, surrounded by mushrooms, microscopes, keys, drying equipment, and mycologists. One mycologist pokes around in another mycologist's collection basket, inspecting, then holds up a little brown mushroom. "You brought in an Inocybe? Why?"

No one cares about Inocybes. With a few purple exceptions, they epitomize the label LBM (Little Brown Mushroom), and are characterized by their brown spore prints, their often conical and usually silky-to-hairy-to-scaly or lacerated caps, and their frequently characteristic odors. There are hundreds of them, and probably hundreds of undocumented, "cryptic" species. In fact Inocybe is often treated less as a genus of mycorrhizal mushrooms than as a mycological rite of passage; if you have not "put a name on" a few Inocybes at some point in your life, good luck getting your (Myco-) Country Club membership. To me, all of this suggests that Inocybe is a prime candidate for demystification. Using a microscope isn't that hard, for crying out loud--and acquiring obscure mycological literature is a relatively simple matter of Interlibrary Loan, even from your public library.

So let's grab our pitchforks and headed for the gated community known as Inocybe Heights. The key below has been under development since 2005; it covers the species that demonstrate purplish shades (anywhere on the mushroom), and the white species (added in 2007). Yes, I am delaying the hard ones with brown and yellowish caps. If you absolutely cannot wait to identify your little brown or yellow Inocybe (it may be several years until I finish the key--and by then some enterprising molecular biologist may well have determined that many or most of the current morphology-defined species are invalid), a list of technical and semi-technical Inocybe sources can be found at the bottom of the page.

The concept of Inocybe has held up amazingly well under DNA scrutiny, which has even supported many of the traditional divisions within the genus (subgenera, sections, and so on). There are some exceptions, of course, but the overall picture, originally painted on the two-dimensional canvas of morphology (physical features as determined with and without a microscope), has been given depth by DNA studies and is beginning to become a three-dimensional sculpture. Since the mushrooms are mycorrhizal, they have obviously evolved in close association with their symbiotic tree partners. While mycologists have not traditionally paid much attention to the documentation of mycorrhizal associations (the paper listed below by Cathy Cripps on "[t]he genus Inocybe in Montana aspen stands" [1997] is a notable exception), it may be the case that this kind of information will help to further elucidate speciation and evolution in Inocybe.

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Unlike most keys at MushroomExpert.Com, this key is frequently microscope-based. There is just no escaping the need for microscopic analysis with Inocybe. Source abbreviations refer to the references list below the key.

References

Abbreviations correspond to those in the key above.

[A] Arora, D. (1986). Mushrooms demystified: A comprehensive guide to the fleshy fungi. Berkeley: Ten Speed Press. 959 pp.

[ATK] Atkinson, G. F. (1918). Some new species of Inocybe. American Journal of Botany 5: 210-218.

[C] Cripps, C. L. (1997). The genus Inocybe in Montana aspen stands. Mycologia 89: 670-688.

[GS1] Grund, D. W. & Stuntz, D. E. (1968). Nova Scotian Inocybes. I. Mycologia 60: 406-425.

[GS2] Grund, D. W. & Stuntz, D. E. (1970). Nova Scotian Inocybes. II. Mycologia 62: 925-939.

[GS3] Grund, D. W. & Stuntz, D. E. (1975). Nova Scotian Inocybes. III. Mycologia 67: 19-31.

[GS4] Grund, D. W. & Stuntz, D. E. (1977). Nova Scotian Inocybes. IV. Mycologia 69: 392-408.

[GS5] Grund, D. W. & Stuntz, D. E. (1980). Nova Scotian Inocybes. V. Mycologia 72: 670-688.

[GS6] Grund, D. W. & Stuntz, D. E. (1981). Nova Scotian Inocybes. VI. Mycologia 73: 655-674.

[GS7] Grund, D. W. & Stuntz, D. E. (1983). Nova Scotian Inocybes. VII. Mycologia 75: 257-270.

[GS8] Grund, D. W. & Stuntz, D. E. (1984). Nova Scotian Inocybes. VIII. Mycologia 76: 733-740.

Hansen, L. & Knudsen, H., eds. (1992). Nordic macromycetes Vol. 2: Polyporales, Boletales, Agaricales, Russulales. Copenhagen: Nordsvamp. 474 pp.

[K1] Kauffman, C.H. (1918). The gilled mushrooms (Agaricaceae) of Michigan and the Great Lakes region, Volumes I and II. New York: Dover. 924 pp. (1971 Reprint.)

Kauffman, C. H. (1920). Studies in the genus Inocybe. The species of Inocybe in Peck's collections. Bulletin of the New York State Museum 233-234: 43-60.

[K2] Kauffman, C. H. (1924). Inocybe. North American Flora 10: 227-260.

[MK] Matheny, P. B. & Kropp, B. R. (2001). A revision of the Inocybe lanuginosa group and allied species in North America. Sydowia 53: 93-139.

Matheny, P. B., Liu, Y. J., Ammirati, J. F. & Hall, B. D. (2002). Using RPB1 sequences to improve phylogenetic inference among mushrooms (Inocybe, Agaricales). American Journal of Botany 89: 688-698.

Matheny, P. B. (2005). Improving phylogenetic inference of mushrooms with RPB1 and RPB2 nucleotide sequences (Inocybe; Agaricales). Molecular Phylogenetics and Evolution 35: 1-20.

Nishida, F. H. (1989). Key to the species of Inocybe in California. Mycotaxon 34: 191-196.

Phillips, R. (2005). Roger's Mushrooms. Retrieved from the World Wide Web: http://www.rogersmushrooms.com (see links below).

Smith, A. H. (1949). Mushrooms in their natural habitat. New York: Hafner Press. 626 pp.

[SS] Smith, A. H. & Stuntz, D. E. (1950). New or noteworthy fungi from Mt. Rainier National Park. Mycologia 42: 80-134.

[SSW] Smith, A. H., Smith, H. V. & Weber, N. S. (1979). How to know the gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 334 pp.

[S47] Stuntz, D. E. (1947). Studies in the genus Inocybe I. New and noteworthy species from Washington. Mycologia 39: 21-55.

Stuntz, D. E. (1954). Studies in the genus Inocybe II. New and noteworthy species from Michigan. Papers of the Michigan Academy of Science, Arts, and Letters 21: 163-197.

[S78] Stuntz, D. E. (1978). Interim skeleton key to some common species of Inocybe in the Pacific Northwest. Notes and species descriptions by Gibson, I. (2004). Retrieved from the Pacific Northwest Key Council Web site: http://www.svims.ca/council/Inocyb.rtf