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Polyporales: The Polypores [ Basidiomycetes . . . ] by Michael Kuo The Polyporales form a large group of diverse mushrooms. Most of these are "polypores" in the widely used sense of the word: they are wood decomposers whose spores are held in tubes (rather like the tubes of the boletes). Many lack fully developed stems, and grow shelf-like or crust-like on wood, while some have more or less central stems and grow at the bases of trees, and a few appear to actually grow terrestrially. Aside from the fact that many of them are attractive and interesting mushrooms, polypores are of special interest to humans because they are wood rotters, assisting in the decomposition of dead wood--and, in many cases, causing rot as pathogens on living wood. Thus the appearance of Laetiporus sulphureus on a living tree, for example, probably signifies the beginning of the end for the tree; inspection of the wood would reveal a reddish brown rot of the heart wood, caused by the mushroom's mycelium. Taxonomically, the polypores are complicated, and not completely understood. Fifty years ago, when L. O. Overholts' thorough study of polypores in North America (1953) was published, nearly all the species of polypores went under the genus name Polyporus. Today, Polyporus is a comparatively small genus, and many separate genera (and families to hold the genera) have been erected. Current DNA studies shift the polypores around on what seems like a daily basis, and a few have been moved out of the polypore order entirely--like Bondarzewia berkeleyi, which is currently placed in the Russulales. See the page on mushroom taxonomy for the most current portrait of polypore taxonomy. Identification of polypores is not an insurmountable task--as is the case, say, in Cortinarius. Careful analysis of the mushroom's macrofeatures is often sufficient to reach a reasonably secure identification decision. The pore surface of a polypore is often distinctive; for example, Daedaleopsis confragosa has a maze-like pore surface, easily distinguished from the pore surfaces of the many polypores with tiny, round pores. Be sure to pay careful attention to the "host" of your polypore, since identification can sometimes hinge on this information. When polypores grow on living trees, this is a matter of identifying the tree. But the more common scenario involves dead wood--in which case one must make assumptions about what kind of dead wood is involved. Notice, at the very least, whether your mushroom grows in conifer woods or among hardwoods. However, if your mushroom is on a very large stump in the midst of a forest full of small trees, it may take some research or guesswork to determine what kind of tree the stump may represent. Other features often important in the identification of polypores include the reaction of the flesh in KOH, and sometimes, microscopic features. I highly recommend Tom Volk's polypore primer for more information on the identification of polypores. Volk is a prominent mycologist who has done significant work with the polypores, including co-authoring the species Laetiporus cincinnatus. |
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(Incomplete) Key to North American Polypores 
I have not yet completed a key to North American polypores, but I have started the ball rolling with a key to the pale-fleshed, stemmed polypores, linked below.
Polypore Sources: Burdsall, H. H. Jr. & Banik, M. T. (2001). The genus Laetiporus in North America. Harvard Papers in Botany 6: 43-55. An online version of this paper can be downloaded here. Gilbertson, R. L. (1980). Wood-rotting fungi of North America. Mycologia 72: 1-49. Gilbertson, R. L. & Ryvarden, L. (1986). North American polypores. Vol. 1. Oslo: Fungiflora. Gilbertson, R. L. & Ryvarden, L. (1987). North American polypores. Vol. 2. Oslo: Fungiflora. Hibbett, D. S. & Donoghue, M. J. (1994). Progress toward a phylogenetic classification of the Polyporaceae through parsimony analysis of mitochondrial ribosomal DNA sequences. Canadian Journal of Botany 73: S853 Krueger, D. (2002). Monographic studies in the genus Polyporus (Basidiomycotina). Ph. D. thesis, The University of Tennessee. Knoxville, TN. 165 pp. Moncalvo, J. M., et al. (1995). Phylogenetic relationships in Ganoderma inferred from the internal transcribed spacers and 25S ribosomal DNA sequences. Mycologia 87: 223-238. Overholts, L. O. (1953). The Polyporaceae of the United States, Alaska and Canada. Ann Arbor: University of Michigan Press. 466 pp. I am particularly fond of this source, though it is outdated in some ways. The keys are well constructed, and Overholts always provides interesting and relevant commentary in his descriptions of species. He is especially attentive to the kinds of rots and decays produced by polypores. Smith, A. H., Smith, H. V. & Weber, N. S. (1981). How to know the non-gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 324 pp. Volk, T. J. (2000). Polypore primer: An introduction to the characters used to identify poroid wood decay fungi. McIlvainea 14: 74-82. (This article can be found online at Tom Volk's Fungi.) Wagner, T. & Fischer, M. (2002). Proceedings towards a natural classification of the worldwide taxa Phellinus s. l. and Inonotus s. l., and phylogenetic relationships of allied genera. Mycologia 94: 998-1016. Polypore Species Pages Abortiporus biennis Cite this page as: Kuo, M. (2004, November). Polyporales: The polypores. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/polyporales.html © MushroomExpert.Com |