That weird mushroom

Not foam rubber and not Geopora or Hydnocystis either but a Gyromitra (false morel) infected by another fungus.


That weird fungus I found last year in June turns out to be two fungi. It, or rather they, were growing from a mossy decomposed log in my woods. The whole thing looked a bit like a chunk of old foam rubber. Not being an expert in fungi I started searching images with queries like “globular fungus” and “tuberous fungus”. This soon led me to truffles and their kin. Then, after seeing cross sections of these globular fungi with their layered interiors, I was steered towards the truffle relatives Geopora and Hydnocystis. By that time I was way off the path to the right identification especially after I saw an exterior shot and cross-section of Geopora cooperi which has a fuzzy exterior and distinctly convoluted interior. (See more photos of Geopora and Hydnocystis here on the Asociacion Vallisoletana de Micologia web site. But G. cooperi, as far as is known, does not grow in Minnesota. Some species of Hydnocystis are reported to grow here, though. I was close, in the right family (Pezizales), but was looking at the wrong genera and missing a very important microscopic feature.

One night I was browsing the internet about another fungus (Datronia scutellata) and came across a very informative site called Weird and Wonderful Wild Mushrooms. Going through the archives I happened upon a post on false morels. The picture of Gyromitra gigas in cross section reminded me of what I had found last year. After some communication with the blogger it turned out that this foam rubber fungus is neither Geopora or Hydnocystis but a Gyromitra, most likely G. esculenta, very common here, that has been infected by another fungus called Sphaeronaemella helvellae. The fuzz over the fungus surface was S. helvellae and not, as I first thought, a coating soft hairs on its surface. So, this is another infected mushroom!

Infection by S. helvellae does more than coat the Gyromitra with fuzz. It also deforms it and this globular deformity and the layered interior led me in the direction of truffle relatives. There are many parasitic fungi that infect other fungi. One genus, Hypomyces, contains some 53 different species that infect a huge range of gilled mushrooms including Russula, Lactarius, Suillus, and Amanita. The mushroom Psathyrella epimyces infects Coprinus, the inky caps, and there are several species of Cordyceps that infect truffles.


Gyromitra esculenta
An uninfected Gyromitra esculenta showing its normal form which I found this year in the same woods.

4 thoughts on “That weird mushroom

  1. Fascinating and very cool, well, not for the poor infected mushroom, I guess. I have yet to really work on identifying the mushrooms and their kin I’ve been photographing and this one give me pause that I’ll be able to do it, but it should be an intellectually engaging activity. I appreciate that you link to the sources you use. I’m saving such links for all sorts of organisms.

    Liked by 1 person

    1. Thanks! It is a challenge to identify them and after this one I am going to use a 10x or greater hand lens more often. I just got a new book on the Ascomycetes (the other fungi group which includes morels and truffles) titled Ascomycete Fungi of North America by MW Beug, AE Bessette, and AR Bessette. Plenty of good color photos and descriptions. I think they cover 600 species. An old book I used to have (and must buy again) is Mushrooms Demystified by D. Arora.

      Gardens a re a great place to find fungi especially if you’ve got lots of mulch. Of course there is also potato blight which I hope will not show up.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s