Good evening, friends,
I took a stroll through Beebe Woods in Falmouth, MA last week on a day when temps were mild and we had just gotten a little rain the previous night. I wanted to see if there were any fresh mushrooms popping up after the rain. Unfortunately, the wind was a counter-force to my efforts that day; it dried up the little precipitation that had fallen and also made me regret wearing shorts.
I decided to cut the stroll short and take a different, shorter trail to get out of the woods. It seems to be that some mushrooms are only found after you’ve decided to call off the search, and that’s exactly how I stumbled upon these peculiar little polypores.
Fun Facts
The facts here might not be so fun, mostly because this fungus eats living tree roots. The economic impact of this fungus on the US timber industry is estimated to be over one billion dollars and the devastation is similar in Europe with an estimated €790 million in lost timber in 1998 (Reference 2). The ecological impact, however? Priceless. A dead tree can serve as habitat for insects, fungi, and bacteria that will both live in and eat the dead wood. Mammals and birds can den in the cavities or eat the organisms that eat the wood. In nature nothing occurs in a vacuum, death begets life.
As it were, this fungus is most problematic when it gets into the unnatural monocultures of a timber plantation because the fungus can spread directly from root to root without having to produce mushrooms.
These mushrooms used to all be classified as Heterobasidion annosum before a closer inspection (specifically DNA sequencing) revealed that there are several different species lumped into what is now the Heterobasidion Annosum complex.
In North America, Heterobasidion irregulare is known to digest pines and junipers across the continent, while Heterobasidion occidentale is only found west of the Rockies and prefers basically all conifers besides pines. A study looked at the secondary metabolites (special chemical compounds) that these two species produced while infecting Norway spruce (Picea albies). H. irregulare produced compounds geared toward detoxifying the spruce’s defense compounds while H. occidentale focused on producing enzymes to break down the sugar’s in the spruce (Reference 3). A neat realization that closely related fungal pathogens can infect the same host but use different chemical pathways to do so.
The etymology of the genus Heterobasidium breaks down to Hetero- which means “different” and -basidion which refers to the internal structure in basidiomycetes that produces spores , the basidium (pl. basidia.) Mushrooms in the genus Heterobasidion have uniquely structured basidia. The species epithet annosum comes from the Latin annōsus and means “long-lived”, which refers to the enduring nature of the pathogen in the wild.
Ecology
Heterobasidion are pathogenic on pine, spruce, fir, and cedar trees - basically any and all conifers - throughout the temperate and boreal forests of the northern hemisphere. In eastern North America specifically, tree species that are particularly susceptible are eastern white pine (Pinus strobus) and eastern red cedar (Juniperus virginiana). Per iNaturalist, the mushrooms grow in the fall but clearly those fruiting bodies can persist over winter.
The vector for infection comes either from spores landing on wounds in the tree or from direct root-to-root contact of infected trees. The fungal mycelium grows throughout the roots and butt of the tree, usurps the nutrients, and chokes out the tree’s vascular system. The mushrooms aren’t always apparent in afflicted trees, but when they are they’ll grow around the trunk or even within hollowed out cavities in the tree.
New York Winter Fungi Fest
I had a nice time on Saturday at Brooklyn Mushroom’s Winter Fungi Fest. It was a tight venue, but almost 1,000 people filtered in and out throughout the day. If you were in the business of promoting a mushroom newsletter and handing out stickers for said mushroom newsletter then you were in the right place. There were food vendors slinging mushroom meals, cultivators presenting on their process, and vendors selling medicinal extracts, teas, and other mushroom wares. Thanks to Zeke and Brooklyn Mushroom for hosting.
I also met a journalist there, Nina Roberts, who writes a Substack specific to small businesses in NYC. Check out her write up of the mushroom festival here.
A Meta Mistake
I made an Instagram account for Mushroom Monday this weekend to have another channel for mushroom pictures and education. I spent a good 90 minutes this morning thoughtfully selecting pictures and crafting my first post. Said post was live for a touch over three hours before the whole account was suspended.
I guess it’s cool for Zuckerberg to hop on Joe Rogan’s podcast, wear a chain and talk a big game about free speech and elk meat (post-presidential election, of course), but gosh forbid I post one picture (out of eight!) of a mushroom that contains psilocybin and we have to shut it all down.
The devil works hard but the content auditors at Meta work harder,
Aubrey
References:
Mellen-McLean, Kim, Bruce G. Marcot, Janet L. Ohmann, Karen Waddell, Elizabeth A. Willhite, Steven A. Acker, Susan A. Livingston, Bruce B. Hostetler, Barbara S. Webb, and Barbara A. Garcia. 2017. DecAID, the decayed wood advisor for managing snags, partially dead trees, and down wood for biodiversity in forests of Washington and Oregon. Version 3.0. USDA Forest Service, Pacific Northwest Region and Pacific Northwest Research Station; USDI Fish and Wildlife Service, Oregon State Office; Portland, Oregon. https://apps.fs.usda.gov/r6_DecAID
Hu Y, Elfstrand M, Stenlid J, Durling MB, Olson Å. The conifer root rot pathogens Heterobasidion irregulare and Heterobasidion occidentale employ different strategies to infect Norway spruce. Sci Rep. 2020 Apr 3;10(1):5884. doi: 10.1038/s41598-020-62521-x. PMID: 32246017; PMCID: PMC7125170.
https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5329398.pdf
https://www.fs.usda.gov/foresthealth/docs/fidls/FIDL-76-HeterobasidionRootDisease.pdf