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White Cheese Polypore - Tyromyces chioneus

Good morning, friends,

Nice to publish MM in the AM, finally. This week's mushroom is Tyromyces chioneus, commonly known as the white cheese polypore. This mushroom was found on 6/9/2022 up in Manitou. I thought I was selecting a fairly straightforward mushroom for today's publication (between you and me, I was looking to get out in the sun as early as possible today) but there are actually a lot of neat aspects to this rather mundane looking polypore - thus reiterating the sentiment that all mushrooms are magic.

Tyromyces chioneus

Fun Facts

A novel sesquiterpene found in a specimen of T. chioneus from the Yunnan Province in China showed strong anti-HIV-1 properties. Interesting not just because of the potential medicinal benefits for HIV-afflicted individuals, but also because a lot of the fungi we have looked at possess documented anti-microbial and antibacterial properties - while this mushroom has a natural anti-viral compound. That's just one of the isolated compounds, the medicinal potential of the other compounds in this mushroom, and in all the under-studied mushrooms, is hard to fathom.

The etymology is fun. Derived from Ancient Greek, Tyromyces means "cheese fungus" or "with a cheesy consistency" while Chioneus means "snow white" - in reference to the color of the mushroom, not the princess.

On my first day up in Manitou last December, I found this orange mushroom below:

Infected Tyromyces chioneus

Turns out it was a white cheese polypore infected by a parasitic ascomycete fungus - perhaps Hypomyces aurantius or Hypocrea pallida. Regardless of the parasite's identity, that's still two fungi for the price of one, folks. T. chioneus isn't necessarily edible - not that it's toxic but it has a wonky, tough texture. However, a species of Hypomyces is responsible for turning a less than desirable Russula mushroom into a choice edible, known as a lobster mushroom, so I wonder if that may be the case here with the parasitized polypore above.

Tyromyces chioneus


T. chioneus is saprobic, growing from hardwoods - particularly birch. Both the specimens showed in this edition of MM were found on sweet birch (Betula lenta). It has pores and white spores. It's found throughout temperate forests in the northern hemisphere - ranging from North America through Europe and into Asia. The mushroom will grow individually, like in the first picture, or in clusters with multiple fruiting bodies as seen below.

A helpful identifying characteristic is that, when squeezed, a fresh mushroom will ooze droplets of water/guttulate (a liquid byproduct of digestion). Additionally, when fresh, it has a fragrant odor that has been described as a sweet, cilantro-like aroma.

Mushroom News

At the beginning of the month, the Fungal Diversity Survey released their Northeast Rare Fungi Challenge. Consisting of 20 seldom seen mushrooms, FunDis released a wonderful booklet you can thumb through, along with instructions on how to participate in the challenge here. Some of these mushrooms are mesmerizing visually, like the indigo blue entoloma and the branched shanklet, while others inhabit unique ecological niches, like the parasitic psathyrella that only grows exclusively on shaggy mane mushrooms, so you'd be remiss not to give the online version of the booklet a study.

I was also pushed an article from Harper's Bazaar, Mommies Who Mushroom, regarding the use of psilocybin to assist with parenting. The connotation may be that it's a vogue and swanky publication, but the article does a nice job summarizing some of the current research and cultural perception pertaining to psychedelics. The pictures are also flashy.

Next weekend I'll be heading out to Castile, NY for the Rochester Area Mycological Association's Both Bolete Foray. I'm anticipating next week's edition of MM will be a robust picture round-up so we can look forward to that.

Happy Independence Day to everyone in the US,


PS. Last week I included a picture of what I thought was Eutypa spinosa from the walk in Central Park. Ethan, from NYMS, was astute enough to point out that it was, instead, Peroneutypa scoparia (Eutypella scoparia) - one of the first ascomycetes that got him interested in that phylum of fungi. Thanks, Ethan, and as always if anyone sees anything wrong or awry do let me know.


1) Kuo, M. (2010, March). Tyromyces chioneus. Retrieved from the MushroomExpert.Com Web site:

2) Liu, DZ., Wang, F., Yang, LM. et al. A New Cadinane Sesquiterpene with Significant Anti-HIV-1 Activity from the Cultures of the Basidiomycete Tyromyces chioneus. J Antibiot 60, 332–334 (2007).


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