Key to 25 Mushroom-Eating Mushrooms and Fungi (Mycotrophs)
by Michael Kuo
The mushrooms and fungi keyed out below are parasites on other mushrooms or saprobes on the remains of other mushrooms. Since so few commonly collected mushrooms play these ecological roles, their identification can be handily economized if you are sure your mushroom or fungus was growing on a mushroom. While mycotrophism is frequently obvious (as in Boletus parasiticus) it can also go unnoticed, since the "victim" mushroom can be blackened and nearly unrecognizable (as in Collybia cirrhata) or even hidden underground (as in Cordyceps ophioglossoides). For this reason most of the mushrooms below are also keyed elsewhere at the site, on the basis of their physical features.
|1.||Mushroom growing out of another mushroom that appears to be the same species (abnormal, "freak" fruitings are not uncommon in the mushroom world, and do not actually represent mycotrophism; click the link to the right to see some examples).|
|1.||Mushroom growing from a different mushroom species.|
|2.||Mycotroph not as above (though victim could still be Gymnopus dryophilus).|
|3.||Mycotroph a crust, fuzz, or mold covering the victim.|
|4.||Mycotroph prominently fuzzy or hairy.|
|4.||Mycotroph not prominently fuzzy or hairy.|
|5.||Mycotroph as scattered, spikelike hairs or dense whitish spike-fuzz on species of Mycena.|
|6.||Victim a bolete or a gilled mushroom.|
|7.||Victim a gilled mushroom.|
|11.||Mycotroph not a bolete; victims various.|
|12.||Mycotroph a club-shaped fungus, with or without a clearly distinct cap; victim an underground puffball.|
|12.||Mycotroph not a club fungus; victims various.|
|13.||Mycotroph with a vague head area but without a clearly distinct, separate cap structure; yellow cords attaching mycotroph to victim.|
|13.||Mycotroph with a clearly distinct cap; yellow cords absent.|
|14.||Mycotroph small (under 3 cm tall), with a purple-black cap and spore segments 2-5 µ long; rare.|
|14.||Mycotroph larger than above (up to 11 cm tall), with variously colored caps and spore segments slightly (3-8 µ) or substantially (8-50 µ) longer than above; fairly common.|
|15.||Mycotroph with cap and stem both dark brown throughout development; spore segments 3-8 µ long.|
|15.||Mycotroph with yellowish stem, at least when young; spore segments 8-50 µ long.|
|16.||Mycotroph with spore segments 8-30 µ long; widely distributed in North America.|
|16.||Mycotroph with spore segments 20-50 µ long; apparently limited to eastern North America.|
|17.||Mycotroph a whitish to pinkish mass of tissue near or among its victims, which are honey mushrooms--and/or among grayish gilled mushrooms with pink gills and mealy odor (which represent "normal" forms of the mycotroph).|
|17.||Mycotroph a gilled mushroom arising directly from its victim; victims various.|
|18.||Mycotroph without a volva; victims various.|
|19.||Spore print of mycotroph white; stem of mycotroph without a ring; victims various.|
|20.||Variously distributed; victims various gilled mushrooms (especially species of Russula).|
|21.||Found in the Pacific Northwest and California; stem of mycotroph long and rooting, with tiny, funky side-branches.|
|21.||Variously distributed; stem of mycotroph not as above.|
|22.||Mycotroph arising from a small mass of tissue (a sclerotium) or from copious white threads; stem of mycotroph about 1-2 mm wide; cap of mycotroph fairly smooth; gills of mycotroph well developed; spores of mycotroph produced only as basidiospores (on basidia located on the gills).|
|22.||Mycotroph not arising from a sclerotium or copious threads; stem of mycotroph wider than above (usually at least 5 mm wide when mature); cap of mycotroph smooth or becoming powdery; gills of mycotroph thick and distant, or poorly formed; spores of mycotroph produced primarily as asexual chlamydospores on the cap surface or gills.|
|23.||Mycotroph arising from sclerotia.|
|24.||Sclerotia pale yellow to orangish, round or nearly so.|
|25.||Cap of mycotroph becoming powdery with maturity; gills of mycotroph poorly formed from the beginning.|
|25.||Cap of mycotroph not becoming powdery; gills of mycotroph thick and well spaced, at least when young.|
Note: Jelly fungi in the genus Tremella (for example, Tremella mesenterica) are parasites on species of Stereum (like Stereum ostrea) and other wood-rotting fungi, but they parasitize the victim's mycelium and are therefore not usually recognized in the field as parasites. For more information, see Tremella mesenterica at Tom Volk's Fungi.
[See also the references on the Hypomyces page.]
Arora, D. (1986). Mushrooms demystified: A comprehensive guide to the fleshy fungi. Berkeley: Ten Speed Press. 959 pp.
Halling, R. E. (1997). A revision of Collyba s.l. in the Northeastern United States and adjacent Canada. Retrieved from the World Wide Web: http://www.nybg.org/bsci/res/col/colintro.html
Kovacs, R. L. & Sundberg, W. J. (1999). Syzygites megalocarpus (Mucorales, Zygomycetes) in Illinois. Transactions of the Illinois State Academy of Science 92: 181-190. Available online at: http://www.il-st-acad-sci.org/transactions/PDF/9217.pdf
Largent, D. L. & Baroni, T. J. (1988). How to identify mushrooms to genus VI: Modern genera. Eureka, CA: Mad River Press. 277 pp.
Mains, E. B. (1957). Species of Cordyceps parasitic on Elaphomyces. Bulletin of the Torrey Botanical Club 84: 243-251.
Smith, A. H., Smith, H. V. & Weber, N. S. (1979). How to know the gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 334 pp.
Smith, A. H., Smith, H. V. & Weber, N. S. (1981). How to know the non-gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 324 pp.
Cite this page as:
Kuo, M. (2006, October). Key to 25 mushroom-eating mushrooms and fungi (mycotrophs). Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/mycotrophs.html