Good evening, friends,
This week we’re looking at a very attractive genus of fall mushrooms, the Scaly Caps (Pholiota spp.). We found these mushrooms up in the Catskills during the Friends of Fungi weekend and you’ll see them popping up throughout the northeast all fall. These are great mushrooms if you like aesthetics and fun facts, not so fun if you like definitive identifications and taxonomy. There are two species - Pholiota squarrosa and Pholiota squarrosoides - that are pretty difficult to tell apart, and we’ll talk about that, but there’s also a lot of promising medicinal properties in these charismatic mushrooms as well.
Fun Facts
There’s some pretty interesting research regarding P. squarrosa, but we’re going to have to decipher a little science-speak to understand. The study out of Japan titled Core fucose-specific Pholiota squarrosa lectin (PhoSL) as a potent broad-spectrum inhibitor of SARS-CoV-2 infection, isn’t exactly self-explanatory. There’s really no need to go that hard in the title.
A lectin is a protein that binds to carbohydrates. There’s a lectin named PhoSL found in Pholiota squamosa which has been researched for a variety of medical uses, varying from the inhibition of COVID and Hepatitis to an early detector for cancer. The idea is that the spike proteins in COVID, and the Hepatitis virus itself, bind to PhoSL instead of human cells. These studies (Reference 3 & 4) were conducted in a lab, not in actual humans. Both hepatitis and COVID are viruses, so this is a little different than other fungi we’ve looked at which have antibacterial compounds.
If you’ve eaten chestnut mushrooms, those are cultivated Pholiota adiposa. Apparently this species also grows in the wild in North America and Europe. The latin Pholiota means “scaly” while squarrosa means “scurfy”. The scurfy scales you see on the cap and stipe are remnants of a universal veil - a membrane that covers the immature mushroom (primordium). The suffix “-oides” in the species squarrosoides denotes likeness and resemblance, as in physically P. squarrosoides looks like P. squarrosa.
Ecology
The fungus is saprobic and decomposes dead wood, but there is also a thinking that some species could be parasitic in instances. P. squarrosa apparently grows on both hardwoods (deciduous) and softwoods (conifers), while P. squarrosoides grows on just hardwoods. It’s not often you see a species as a decomposer of both conifers and hardwoods, so that makes me wonder how often P. squarrosa is confused with other Pholiota species. Both species are widely distributed across the northern hemisphere and grow summer through fall (though I typically only see Pholiota in the fall).
Pholiota species all exhibit a cespitose growth pattern which means their stipes are all tightly packed and sometimes even fused together at the base of the mushrooms.
There are supposedly three markers for determining the difference between P. squarrosa and P. squarrosoides in the field. The gills on P. squarrosa turn from white to green to brown (because of the brown spores) whereas on P. squarrosoides they go right from white to brown, no green. Secondly, underneath those pronounced scales P. squarrosoides has a sticky cap while P. squarrosa is theoretically drier. Lastly, P. squarrosa can at times smell like garlic, while P. squarrosoides is odorless. If you do have a microscope, P. squarrosoides has much smaller spores.
Of course then there’s Pholiota alnicola and Pholiota limonella which grow on conifers, Pholiota aurivella which grows in New Zealand and North America (?), and the edible Pholiota adiposa mentioned earlier. They all look pretty similar and are begging for someone with a little extra time on their hands to decipher their nuances.
It’s been a bit slow for mushrooms on the preserve. The September drought definitely ground most of the above-ground fungal growth to a halt, but I’m hoping another rain early next week will reinvigorate the fall mycorrhizals.
My schedule was a little wonky this past week, that’s why we’re here on a Wednesday, but I’ll be back to Tuesday next week. Soil class runs until mid-November so it’s Toadstool Tuesday until then.
New moon tonight,
Aubrey
References:
Kuo, M. (2007, November). Pholiota squarrosoides. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/pholiota_squarrosoides.html
Kuo, M. (2007, November). Pholiota squarrosa. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/pholiota_squarrosa.html
Yamasaki K, Adachi N, Ngwe Tun MM, Ikeda A, Moriya T, Kawasaki M, Yamasaki T, Kubota T, Nagashima I, Shimizu H, Tateno H, Morita K. Core fucose-specific Pholiota squarrosa lectin (PhoSL) as a potent broad-spectrum inhibitor of SARS-CoV-2 infection. FEBS J. 2023 Jan;290(2):412-427. doi: 10.1111/febs.16599. Epub 2022 Sep 5. PMID: 36007953; PMCID: PMC9539343.
Ouchida T, Maeda H, Akamatsu Y, Maeda M, Takamatsu S, Kondo J, Misaki R, Kamada Y, Ueda M, Ueda K, Miyoshi E. The specific core fucose-binding lectin Pholiota squarrosa lectin (PhoSL) inhibits hepatitis B virus infection in vitro. Sci Rep. 2023 Apr 15;13(1):6175. doi: 10.1038/s41598-023-28572-6. PMID: 37061516; PMCID: PMC10105536.
https://www.mobot.org/mobot/latindict/keyDetail.aspx?keyWord=squarrosus
https://www.inaturalist.org/taxa/157728-Pholiota-squarrosoides