Asterophora lycoperdoides, the star bearing powder cap mushroom         

Tom Volk's Fungus of the Month for December 2005

by Jon Palmer and Tom Volk

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For a special holiday treat click on "Fungi that are necessary for a merry Christmas"

Fruiting bodies of Asterophora lycoperdoides, photo by Sean Westmoreland

This month's Fungus is Asterophora lycoperdoides, is a relatively rare and interesting fungus that parasitizes other mushrooms in the Russulales (Russula and Lactarius). Although it occasionally found in great abundance in special locations in the fall, we certainly don't find this mushroom here during the holiday season; in fact we don't find anything here during this time of the year except snow and ice! However, Asterophora has star-shaped spores, so it is quite appropriate for Christmas. The genus name Asterophora means "star bearer," and the epithet lycoperdoides means "like Lycoperdon," the wolf-fart puffball.

Here in Wisconsin, on the rare occasion that we find A. lycoperdoides, it is usually growing on old fruiting bodies of Russula nigricans, which is part of a cluster of similar species (a "species complex"). David Arora refers to this species complex as the Russula densifolia group, you may call it whatever name you prefer, keeping in mind that Russula species are notoriously hard to identify. This particular species complex tends to turn dark brown to black quite early in age, as its flesh turns a pink or red color. When you stumble upon this parasitic duo in nature, you assume that it is well past its prime and definitely not something you would want to collect. In fact you may even pretend that you didn't even see it, much like some "regular" people miss all the mycologically interesting things around them. Remember that even the smallest and/or the "ugliest" of mushrooms may be the most interesting.

Although Asterophora lycoperdoides is a member of the Basidiomycota, it rarely produces basidiospores. Remember that fungi are classified by their method of producing sexual spores. (For a refresher see here.) Instead of producing basidiospores, the "powder cap" makes abundant asexual chlamydospores on top of the mushroom cap. The spores are sometimes so abundant that you seem to be covered in them after handling this mushroom. This is a very unusual mode of spore production for a member of the Basidiomycota, which usually don't have an asexual state at all. Immature basidiocarps are all white in color before the hyphae on the cap cuticle form the brown chlamydospores (A - see picture below).

chlamydospores of A. lycoperdoides

Asterophora is a small genus that contains only two species, A. lycoperdoides and A. parasitica. The gills of Asterophora lycoperdoides are often absent or deformed looking. You are sometimes able to see striations that appear that they once might have been gills (C - click here or on the picture on the right to take a closer look). Although it also grows on mushrooms, A. parasitica interestingly does not produce a chlamydospore stage, but rather forms a conventional fruiting body with gills and basidiospores.

Like most fungal names, Asterophora has been through taxonomic flux. For the past 175 years two names have been used interchangeably to describe this genus, Asterophora and Nyctalis. Initial confusion of which name to use was due to not fully understanding the biology of this unique mushroom. Recent arguments were focused on whether Asterophora was first described as the anamorphic state (asexual) or the teleomorphic state (sexual). Redhead and Siefert (Redhead, S. A. and K. A. Seifert. 2001. Asterophora Ditmar ex Link 1809 versus Nyctalis Fries 1825 and the status of Ugola Adanson 1763. Taxon 50: 243-268) came to the conclusion that Asterophora should be the correct name because it was described as the teleomorph (sexual) in 1809 by Ditmar ex Link, which is before Fries's description of Nyctalis in 1825. The asexual state (anamorph) name is Ugola and it appears to be in a yeast form. Remember that if both the anamorph and teleomorph names are known that the correct name to use is the teleomorph.

Chlamydospores are thick-walled asexual spores produced by fungal hyphae (B - shown on the right). These spores are formed by the hyphae swelling or coiling up into sort of a ball of hyphal tissue. These spores are used by some fungi as long-term resting spores and by others, such as Asterophora, as the main reproductive spore. Most fungi in lab can be induced to form chlamydospores but some of them demonstrate a prominent chlamydospore stage-- for example the dermatophytessuch as the cause of athletes foot,, and Candida albicans, the cause of most yeast infections,

Although chlamydospores and conidia are both forms of asexual reproduction in fungi, they are distinguished from one another by how they are made. Conidia are asexual spores that are borne from a conidiophore, or a reproductive cell, and the spores are usually formed at the tip of this cell. This is called blastic conidiation, as you can see in Penicillium or Aspergillus. Notice how these conidia are different than the chlamydospores shown on the right, in panel B. Technically, chlamydospores aren't actually spores at all; rather they are formed by hyphae swelling or coiling up into a ball of hyphal tissue, followed by the laying down of a thick wall that prevents drying out. This is why the ornamentation of the chlamydospore wall appears to be somewhat chaotic, meaning there isn't a regular form of ornamentation that is seen in all of the chlamydospores. We sometimes refer to them as "spores." for lack of a better term and because of tradition. We're stuck with a lot of terms that have been misapplied. Remember that the cereal Grape NutsTM contains neither grapes nor nuts.

Jon PalmerThis month's co-author is one of my graduate students, Jon Palmer. Jon is doing his thesis work on (mostly mycorrhizal) fungi associated with the American chestnut (Castanea dentata). He is one of the best field mycologists I have trained, and he backs this up with excellent laboratory skills. You should offer him a job.

We both hope you enjoyed learning about a strange looking fungus with interesting spores. Sometimes the most overlooked fungi are the most interesting.

If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at

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