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Ochre Spreading Tooth - Steccherinum ochraceum

Good evening, friends,


This week we’re going to keep with the crust-like fungi and learn about the Ochre Spreading Tooth (Steccherinum ochraceum). This mushroom grows like a crust, similar to Peniophora incarnata from last week and even more similar to the winter fungus Irpex lacteus, but the tiny spines protruding from the underside actually distinguish this as a toothed mushroom (like lion’s mane). Classifications aside, this subtly handsome fungus serves an important ecological function and you can find it outside right now doing its job.


Steccherinum ochraceum

Fun Facts


The fungus has been the focus of a surprising amount of scientific studies (thirteen) compared to many of the other mushrooms we learn about. The main area of interest for researchers is S. ochraceum’s ability to produce unique enzymes which the fungus uses to digest wood. Studies have tried to examine different applications for these enzymes which range from bioremediation technologies to anti-cancer treatments - although none have shown much promise, unfortunately.


Extracts from the fungus also displayed antibacterial activity against Staphylococcus aureus, a bacteria harmful to humans (Reference 3). S. aureus has already displayed resistance to human antibiotics in the form of MRSA (Methicillin-resistant Staphylococcus aureus) so it’s always good to find potential alternative medicines.


The teeth are forked at the top, in theory, but even with a hand lens I had trouble seeing that.
The teeth are forked at the top, in theory, but even with a hand lens I had trouble seeing that.

For the life of me I couldn’t figure out what the etymology of Steccherinum means, but the fungus used to be in the genus Hydnum which comes from the greek udnon and means “truffle”. The species epithet, ochraceum, refers to the ochre color of the fertile surface which fades to a salmon color with age.


The fruiting bodies can start off as small, millimeter in diameter, circles before fusing together to form a large, contiguous surface.
The fruiting bodies can start off as small, millimeter in diameter, circles before fusing together to form a large, contiguous surface.

Ecology


The fungus is saprobic and decomposes dead hardwood trees (very seldom conifers). The fungus is also apparently a pathogen on sweetgum trees (Liquidambar styraciflua). I found this on black birch (Betula lenta) with Crimped Gill (Plicaturopsis crispa) and, perhaps next week’s mushroom, the Veiled Panus (Tectella patellaris), both growing nearby on the same branch.


P. crispa is considered a primary decomposer (one of the first fungi to digest recently dead wood), and S. ochraceum is considered a “secondary colonizing fungus”, so this duo is an example of ecological succession in real-time. The first fungus creates the optimal conditions for the second. Although, I imagine since they’re digesting different parts of the wood (not competing with each other), they’re both able to grow simultaneously on this branch. As a secondary decomposer, S. ochraceum is kind of like goldilocks in that the wood can’t be too fresh nor too old, it needs to be in just the right stage of decay.


Steccherinum ochraceum

The mushroom has an ochre (yellowish brown), toothed fertile surface (where spores are released). This is ringed by a white, infertile margin. The mushroom grows resupinate along the bottom of the substrate (as if its painted on), oriented with the pull of gravity, but can form small effused-reflexed caps at the margin of the branch. These caps can be white, ringed, and hairy (seen above).


S. ochraceum is more commonly found east of the Rockies in North America and can be found throughout temperate regions of the northern hemisphere. Apparently the mushroom grows summer through fall but can be found year-round with iNaturalist observations peaking October through January.


Steccherinum ochraceum

Thanks for reading. Full moon on Saturday,

Aubrey


References:

  1. Kuo, M. (2010, May). Steccherinum ochraceum. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/steccherinum_ochraceum.html

  2. Liu DZ, Luo MH. Two new chamigrane metabolites from fermentation broth of Steccherinum ochraceum. Fitoterapia. 2010 Dec;81(8):1205-7. doi: 10.1016/j.fitote.2010.08.004. Epub 2010 Aug 17. PMID: 20723585.

  3. Moiseenko KV, Glazunova OA, Shakhova NV, Savinova OS, Vasina DV, Tyazhelova TV, Psurtseva NV, Fedorova TV. Fungal Adaptation to the Advanced Stages of Wood Decomposition: Insights from the Steccherinum ochraceum. Microorganisms. 2019 Nov 5;7(11):527. doi: 10.3390/microorganisms7110527. PMID: 31694151; PMCID: PMC6921079.

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