March 28, 2022
Good evening, friends,
We’re staying on island (electronically, not physically unfortunately) for this week’s mushroom: Hexagonia hydnoides, commonly known as hairy hexagonia. We were quite bewildered when we found this bewhiskered beaut, but this bristly polypore isn’t just a relic of the tropics – it can be found in the continental US too!
Extracts of H. hydnoides in ethyl acetate inhibited the growth of the bacteria Bacillus cereus. B. cereus is a foodborne pathogen that causes gastrointestinal distress in humans (food poisoning).
The fourth reference is a newsletter from MushRumors, the newsletter of the Northwest Mushroomers Association, in which Buck Mcadoo postulates that the hirsute (hairy) cap of H. hydnoides acts as a sponge to retain moisture after rain. This would allow the pore surface to keep producing spores well after the moisture in the air has dissipated.
Kurt mentioned that the mushroom can also come in handy as a natural Brillo pad to clean pots and pans while camping. While more research is needed to identify how some of the compounds in the mushroom can serve as an antibiotic/anti-bacterial, this is a practical application that can be used without any further manipulation. Imagine using it as a sponge for your own dishes, and instead of soap you simply rely on the anti-bacterial compounds naturally produced within the mushroom…now we’re thinking big, folks.
H. hydnoides is saprobic on hardwoods – and it doesn’t seem discriminate between hardwood species – but it has not been found on conifers (…yet). In H. hydnoides’ three sentence description on Wikipedia, it’s listed as a plant pathogen, but my hypothesis is that it creates a heart rot in living trees – consuming the dead xylem cells in the center of the tree – and then fruits on these trees. As the mushrooms age, the conspicuous hairs on the top of the cap fall weather away which would make identification of this species more difficult.
It’s found primarily in the tropics, ranging from Puerto Rico down through Brazil, across to Madagascar, Thailand, and Australia. In the US it’s primarily found in the gulf states, but has been seen as far north as Kansas. There are hundreds of observations on iNaturalist further north than Kansas, but a lot of them are the iNaturalist AI giving a faulty recommendation for a one picture observation of a desiccated polypore. I didn’t purse through all of them to determine the furthest northern most occurrence in the US but I don’t think this species is occurring in Maine and Canada as iNat would lead you to believe.
There is a bruising on the pore surface of white to brown when rubbed/damaged. This, along with the black, hairy top are helpful identification characteristics.
April fool’s is on Friday (as is the new moon) – so stay sharp!
PS. Here are some oyster mushrooms, Pleurotus ostreatus, I found this past week growing on downed hardwood – the first gilled mushrooms of 2022 up here:
1) Kuo, M. (2019, January). Hexagonia hydnoides. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/hexagonia_hydnoides.html
2) Grumezescu, A. M., & Holban, A. M. (2018). Chapter 5: Prebiotics and Their Production From Unconventional Raw Materials (Mushrooms). In Therapeutic, probiotic, and Unconventional Foods (p. 93). https://books.google.com/books