Tom Volk's Fungus of the Month for May 2004

Coprinus comatus, the shaggy mane

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Coprinus comatus, photo by Hal Burdsall This month's fungus is Coprinus comatus, the shaggy mane mushroom, also known as the "lawyer's wig." It is a delicious edible mushroom, one of Clyde Christensen's "Foolprof Four," which also includes Morchella species, the morels, Calvatia gigantea, the giant puffball, and Laetiporus sulphureus, the chicken of the woods, or sulfur shelf mushroom. Clyde Christensen was a professor at the University of Minnesota who published the "Foolproof Four" in 1943 in a book called "Common Edible Mushrooms" in 1943. His intention was to popularize mushroom hunting by educating the generally mycophobic public that there are in fact some edible mushroom that are easily identified. However, as I said in my lecture on the "Foolproof Four" at the NAMA foray in Minnesota in 2001, many things have changed in mycology in the past 60 years. Dr. Christensen (or anyone else) could not have predicted what would become of what seemed like straightforward taxonomy. Many of your favorite mushrooms have undergone several name changes and splitting of species. For example, we still don't know how many species of morels there are throughout the world, nor how to go about identifying the many species. According to molecular data, the giant puffball now appears to be closely related to Agaricus! And perhaps not too surprisingly, Laetiporus sulphureus has been split into about 7 species, most of which are easy to identify by color, host species, position on the tree, and geography. You can read more about the changes to those three fungi on their respective pages. I will tell you a lot more about Coprinus here -- and you mushroom identifiers are probably not going to like it.

inky gills of CoprinusMembers of the genus Coprinus have been collectively known as the "inky caps" because of the curious character of autodeliquescence of their gills-- in other words self-digestion to release their basidiospores. Most of these species have gills that are very thin and very close to one another, which does not allow for easy release of the spores. Moreover the elongated shape of mushroom does not allow for the spores to be shot off the basidia and get caught in air currents as in most other mushrooms. Coprinus species "compensate" for this by a sequential maturation of the spores from the bottom of the gill towards the top. After the spores have matured and been released, the gill tissue digests itself and begins to curl up, allowing easy release of the basidiospores above. In other words, the digestion opens up the fruiting body so that spores from further up the gills become exposed to the air and a clear path of spore release. The self-digestion continues until the entire fruiting body has turned to black ink. In the olden days this ink was actually used for writing. The self-digestion is also a way of releasing the spores over a longer period of time, and allowing the release of spores from very closely spaced narrow gills borne inside a longitudinally tall pileus. If any Coprinus species are collected for eating or for scientific study, they must be cooked or dried right away, since the self-digesting enzymes seem to kick into high gear after the mushroom is removed from its substrate. They're pretty easy to find too-- the genus name Coprinus gives you a pretty good idea where to look for these mushrooms-- in dung or very rich organic soil.

Coprinus species turning inkyCoprinus used to be the one of the easiest mushroom genera to identify. All you had to do was look for the self-digestion of the gills. But what was once considered an "easy" genus is now a little trickier. In 1994 graduate student John Hopple did some PCR-based systematics experiments in Rytas Vilgalys' lab at Duke University. He sequenced a certain gene and found that the self-digesting fungi actually belonged to four different groups. There was significant controversy when he presented his data at the Mycological Society of America meeting. How could such a distinctive group be so diverse? The proposal to split the genus up was met with such outrage that this was not published until about 8 years later. Also controversial was the assertion that the species could not be classified into the same family.

Based on DNA studies and morphological data, there does not appear to be much question among mycologists that there are indeed four distinct genera of fungi that have self-digesting gills. The only controversy is what to call the four groups. Are they indeed different enough to be called genera? The data surely point that way, so mycologists were given the task of naming the four groups. So which taxon should retain the name Coprinus?

Scott Redhead, one of North America's most prominent extant agaricologists, has published several papers on this problem and has proposed names for the four genera after careful morphological study of the fungi involved. One major contribution of molecular techniques is that they force mycologists to go back and more closely examine the morphology. Maybe the characters that we used to separate genera and species in the past were not really valid. There are very specific rules called the "International Code of Botanical Nomenclature"(or simply "the Code") that govern how species should be named.

cottony string extracted from the center of the C. comatus stipeUnfortunately, as is many times the case, the oddball species is the type species of the genus. With Coprinus comatus as the type species, the genus becomes more narrowly defined: very close think gills, floccose scales, stipe with central extractable cottony yarn-like string. That means that there are only 3 species are left in Coprinus: Coprinus comatus, C. sterquilinus, and C. spadiceosporus. The latter two species are nearly identical in appearance to C. comatus. Even more surprising is that molecular data places C. comatus belongs in the Agaricaceae! Since Coprinus is also the type genus of the Coprinaceae (formerly defined as having brown/black spore print; gills attached; saprophytes on ground or on wood), this inclusion of Coprinus in the Agaricaceae means that Coprinaceae becomes a later synonym of the older name Agaricaceae, and is thus invalid.

A=Coprinus comatus, B=Coprinopsis variegata (=C. quadrifidus) , C=Coprinellus micaceus, D=Parasola plicatilisSo where do the rest of the species go? Molecular data places the other three genera with the genus Psathyrella, so the family Psathyrellaceae (Singer) Vilgalys, Moncalvo & Redhead (Taxon 2001) was erected. Besides the genus Psathyrella, three new genera were recognized: Coprinopsis, Coprinellus, and Parasola.

Coprinopsis (B) means "like Coprinus" and was recognized by Karsten in 1881-- veil present, often leaving ephemeral (i.e. easily removed) shaggy scales or broad membranous patches on the pileus, lamellae (gills) always deliquescent. This includes the familiar species Coprinopsis atramentaria, Coprinopsis lagopus, Coprinopsis cinerea, Coprinopsis variegata , (=C. quadrifidus), plus about 100 other species

Coprinellus (C) means "little Coprinus" and was recognized by Karsten in 1879. Members of this genus also have a veil present, but lack the ephemeral scales of Coprinopsis. The lamellae and pileus are fully, partially or non-deliquescent. This genus includes the familiar species Coprinellus micaceus, Coprinellus disseminatus, Coprinellus domesticus, Coprinellus radians, plus about 45 others.

Parasola (D) means "parasol (shaped)" and was newly described in the Redhead et al. (2001)Taxon paper below. Members of this genus have no veil and are very fragile. The gills are non-deliquescent, and pleurocystidia always present; differences in pileipellis (cap cuticle) also. This includes the familiar species Parasola plicatilis plus about 17 others.

So is this the final word on Coprinus and its segregate genera? No! Some Europeans want to accept a different type species for Coprinus, making fewer name changes necessary. However, there is not much dispute as to whether four genera are represented; the only real controversy is what we should call them. Fungus names should reflect evolutionary relationships and give an indication of characters in common, and these almost certainly represent distinct genera based on these criteria.

Should the type of Coprinus be changed? Read what Lorelei Norvell has to say about it here.

For more information on Coprinus and its systematics, you can read the following papers:

Scott Redhead (2001) "Bully for Coprinus - - a story of manure, minutiae, and molecules" McIlvainea 14(2): 5 - 14

Coprinus Persoon and the disposition of Coprinus species sensu lato (2001) . Scott A. Redhead, Rytas Vilgalys, Jean-Marc Moncalvo, Jacqui Johnson & John S. Hopple, Jr. Taxon 50:203-241

You can read LOTS more about Coprinus and related genera at Kees Uljé's "All about Inkcaps."

I hope you enjoyed learning something about Coprinus comatus and friends. Try out your new found knowledge at your next foray or mycological event! But be prepared to get the rolling eye treatment, or even some cursory cursing, from your mycological friends.

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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