The Ascomycetes

by Michael Kuo

The mushrooms in the Ascomycetes have spores that are produced in specialized holding cells called "asci." An ascus (singular of "asci") usually holds eight spores, as in the illustration, but the number may vary greatly. The spores are ejected through the end of the ascus, where an opening develops. A mushroom belonging to the Ascomycetes has a fertile surface that is covered with asci--in the morels, for example, this surface is the pitted surface of the cap.

The number of fungi belonging in the Ascomycetes is stunning (over 15,000!)--but, fortunately for mushroomers, most of these fungi are yeasts, mildews, molds, and so on. A smaller number of the Ascomycetes actually produce fruiting bodies that could be called "mushrooms," most notably the morels, false morels, saddles, and most of the cup fungi.

There is no definitive way to determine, without using a microscope, whether or not a mushroom belongs to the Ascomycetes or the Basidiomycetes. 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 Ascomycetes, 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. Our keys begin with the Key to Major Groups of Mushrooms.

Larsen, H. J. (1980). Key to the genera of the operculate cup-fungi (PEZIZALES) of the Pacific Northwest and Rocky Mountain region. Retrieved from the Pacific Northwest Key Council Web site: http://www.svims.ca/council/Peziza.htm

O'Donnell, K. O., et al. (1997). Phylogenetic relationships among ascomycetous truffles and the true and false morels inferred from 18S and 28S ribosomal DNA sequence analysis. Mycologia 89: 48-65.

Perry, B. A., K. Hansen & D. H. Pfister (2007). A phylogenetic overview of the family Pyronemataceae (Ascomycota, Pezizales). Mycological Research 111: 549-571.

Seaver, F. J. (1928). The North American Cup-fungi (Operculates). New York: Lancaster Press. 284 pp.

Seaver, F. J. (1951). The North American Cup-fungi (Inoperculates). New York: Lancaster Press. 428 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.

Tedersoo, L., K. Hansen, B. A. Perry & R. Kjoller (2006). Molecular and morphological diversity of pezizalean ectomycorrhiza. New Phytologist 170: 581-596.

Weber, N. S. (1997). Pez-Web: Western North American Pezizales. Retrieved from the World Wide Web: http://mgd.nacse.org/hyperSQL/pezweb/

Weber, N. S. et al. (1997). Studies on western American Pezizales. Collecting and describing ascomata--macroscopic features. Mycotaxon 61: 153-176.

Wicklow, D. T. & Hirschfield, B. J. (1979). Competitive hierarchy in postfire ascomycetes. Mycologia 71: 47-54.

Winka, K. (2000). Phylogenetic relationships within the Ascomycota based on 18S rDNA sequences. Ph.D. thesis, Umea University, Sweden. 25 pp. Retrieved from the Umea University Web Site: http://www.eg.umu.se/phdpdf/katarina_winka.pdf

Cite this page as:

Kuo, M. (2004, November). The Ascomycetes.Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/ascomycetes.html