Toadstool Tuesday
False turkey tail (Stereum ostrea complex)
Good evening, friends,
The mystery of mushrooms is what draws a lot of people into the study of mycology. When I started learning about mushrooms a mere five years ago, I was surprised that we don’t even have a good grasp on some of the most common mushrooms in the woods.
False turkey tail in North America used to all be called Stereum ostrea and that’s how you’ll see these crusts labeled in your identification books. However, a master’s thesis by Sarah DeLong-Duhon and Robin K. Bagley revealed that there are (at least) three genetically unique species in eastern North America. One better, you can even differentiate between the three in the field using a few diagnostic characteristics. I should note that this paper has not been formally peer-reviewed, and while I may not be a peer in the academic sense, I certainly did some review and learned a whole lot.
The paper starts off by noting that there are somewhere between 2.2 and 3.8 million species of fungi in the world (a modest range of 1.6 million) and only 120,000 have been described. Most fungi don’t produce mushrooms so finding and identifying filamentous strands of hyphae in wood and soil isn’t particularly accessible for everyone, which could explain the lag in identifications to this point. Forget filamentous strands for a second though, these false turkey tails are one of - if not the - most common mushrooms in the woods and we didn’t formally realize there were differences in them until a couple years ago. The further we go, the less we know.
Stereum
Stereum are crust fungi that don’t have pores, gills, nor teeth, and instead have a smooth underside (fertile surface, hymenium) from which their spores are released. That was news to me, I thought Stereum were polypores like turkey tail (Trametes versicolor) because they form shelves on wood like other polypores. Both are decomposers of wood, but the biggest observable difference between the false turkey tail and the real turkey tail is the underside. While both have concentric bands of color on the top of the cap, Trametes versicolor has a white, pored underside.
Stereum comes from the Greek stereos which means solid, and these scallop-shaped crusts can persist on wood for over a year after they originally fruit. This means you can find them year-round and right now in the midst of a drought they’re some of the only mushrooms you’ll find.
The Three Stereum Species
The Stereum Ostrea complex in eastern North America can be broken up into three different species: Stereum fasciatum, Stereum lobatum, and Stereum subtomentosum. If the underside of the mushroom darkens when you wet it, but does not turn yellow, then you have Stereum fasciatum. You can use your saliva to wet the mushroom so this is something you can do right in the field.
If the mushroom’s underside does turn yellow, then you have either Stereum lobatum or Stereum subtomentosum. S. lobatum has matted hairs (tomentum) so dense that you can’t see the individual hairs. S. lobatum also has more chestnut-colored bands that widen as that white tomentum is worn away with age.
S. subtomentosum on the other hand, referred to as the Yellowing Curtain Crust on iNaturalist, tends to have fewer chestnut-colored bands. You can also parse out the individual hairs on the cap. I picked up a trick from the New York Mycological Society that if you bend the cap, and the hairs are sticking up vertically then you’ve got S. subtomentosum. If they’re matted down, S. lobatum. Unfortunately, a lot of the specimens I found were so old and dry they just broke in half. No bend at all. In my mushrooming I didn’t find any S. subtomentosum, but I’m going to examine all these Stereum a lot more closely now.
The author of the study also created a key to help differentiate between the three species here. I took a shot at identifying the mushrooms in the pictures today, but like always I could be wrong. I’ve previously written about crowded parchment (Stereum complicatum), but the three species we learned about today are all larger. Counterintuitively, S. complicatum might be the least complicated to identify.
There are dozens of studies on the potential antioxidant and antibacterial activity in different species of Stereum. Coincidentally, I stumbled on two different studies from the same school in Serbia, shoutout to the University of Novi Sad. One study looked at Stereum hirsutum’s acetylcholinesterase inhibition and the potential of the mushroom for use in treating Alzheimers, just like last week’s blue cheese polypore. I guess if you want a good grasp on Stereum you’ve got to get out to Serbia.
Looks like we’ll finally get some substantial rain later this week. Much, much needed. My soil science class is finally over, so we’ll be back on Monday next week. That’ll be my last traditional MM before I take a break in December to work on a longer project.
Stay tuned, lots in the works,
Aubrey
References:
DeLong-Duhon, Sarah G, and Robin K Bagley. “DNA, Morphology, and Ecology Resurrect Previously Synonymized Species of North American Stereum and Suggest Extensive Undescribed Global Diversity.” BioRxiv (Cold Spring Harbor Laboratory), 16 Oct. 2020, https://doi.org/10.1101/2020.10.16.342840.
https://www.inaturalist.org/posts/97401-sarah-delong-duhon-s-stereum-ostrea-group-key#summary
Mišković J, Rašeta M, Čapelja E, Krsmanović N, Novaković A, Karaman M. Mushroom Species Stereum hirsutum as Natural Source of Phenolics and Fatty Acids as Antioxidants and Acetylcholinesterase Inhibitors. Chem Biodivers. 2021 Nov;18(11):e2100409. doi: 10.1002/cbdv.202100409. Epub 2021 Oct 20. PMID: 34467660.
Rašeta M, Popović M, Knežević P, Šibul F, Kaišarević S, Karaman M. Bioactive Phenolic Compounds of Two Medicinal Mushroom Species Trametes versicolor and Stereum subtomentosum as Antioxidant and Antiproliferative Agents. Chem Biodivers. 2020 Dec;17(12):e2000683. doi: 10.1002/cbdv.202000683. Epub 2020 Nov 17. PMID: 33058392.