The Basidiomycetes

by Michael Kuo

The mushrooms in the Basidiomycetes have spores that are attached to basidia, which are specialized cells on the spore-bearing surface (for example, the gills). When the spores mature they are flung from the basidia (by means of a nifty trick involving a tiny water droplet and gravity), catching the slightest air currents and, unlike the proverbial acorn, often falling far from the "tree."

Basidia are typically "four-spored" or "two-spored." Tiny projections from the end of the basidium, called sterigmata, bear the spores. Illustrated to the right are a two-spored basidium and a four-spored basidium. Basidia are typically somewhat club-shaped, as in the four-spored example, but some groups of mushrooms (like the Hygrophoraceae) have narrow basidia, as in the two-spored example.

The rusts, smuts (and so on) producing spores on basidia are not treated at this Web site. You are welcome to try finding RustExpert.Com or SmutExpert.Com--but my suspicion is that neither site would be quite what you're looking for.

Basidia holding spores

There is no definitive way to determine, without using a microscope, whether or not a mushroom belongs to the Basidiomycetes or the Ascomycetes. However, all the gilled mushrooms are Basidiomycetes, as are all of the mushrooms with pores, including the polypores and boletes. This narrows things down considerably, and after you have collected and observed a good many mushrooms, you are likely to acquire a sense of which mushrooms are Ascomycetes and which are Basidiomycetes--though some groups (especially the mushrooms shaped like clubs) will forever remain confusing until you quit your job and learn the mushrooms one by one.

To see how mycologists currently separate the various families and genera in the Basidiomycetes, click here. However, if you are trying to identify a mushroom, such a taxonomical arrangement is not likely to help much, unless you have access to a microscope and, in many cases, a DNA laboratory. For this reason the identification keys at this site are not arranged taxonomically, and are based on features that amateur mushroomers can observe. The site's keys begin with the Key to Major Groups of Mushrooms.

References for Basidiomycetes

Note: The sources below treat the evolution and phylogeny of the Basidiomycetes, as a group. For identification of Basidiomycetes, see individual genus and family pages, as well as the References page.

Hibbett, D. S. et al. (1997). Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of Homobasidiomycetes. American Journal of Botany 84: 981-991.

Hibbett, D. S. et al. (1997). Evolution of gilled mushrooms and puffballs inferred from ribosomal DNA sequences. Proceedings of the National Academy of Sciences 94: 12002-12006.

Hibbett, D. S. et al. (2003). Another fossil agaric from Dominican amber. Mycologia 95: 685-687.

Larsson, E. & Larsson, K. H. (2003). Phylogenetic relationships of russuloid basidiomycetes with an emphasis on aphyllophoralean taxa. Mycologia 95: 1037-1065.

Moncalvo, J. M., et al. (2002). One hundred and seventeen clades of euagarics. Molecular Phylogenetics and Evolution 23: 357400. An online version of this paper is available at:

Cite this page as:

Kuo, M. (2007, February). The Basidiomycetes. Retrieved from the MushroomExpert.Com Web site:

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