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Birch polypore is a common fungus that grows from birch trees. Photo by Emily Stone.

The rocky trail led up and over and around tree roots and boulders, and we hiked steadily to stay warm. As we navigated the stairs of a birch tree’s roots, my friend pointed out a pale grayish fungus poking out from the trunk like a small, fat Frisbee.

“Birch polypore,” I offered reflexively, not needing to think at all about the name of this common and easily recognized species. Not having been on very many hikes with me, they were startled by this casual identification, and burst out in surprised laughter. This made me chuckle, and soon we were both giggling down the trail.  

That laughter was good medicine, and fitting that it came from a mushroom with so many uses. Birch polypore, or Fomitopsis betulina is a bracket fungus who grows on birch trees around North America, the British Isles, Europe, and Asia.

This fungi’s big moment of fame came with the discovery of Otzi the Iceman, a 5,300-year-old man frozen in the Italian Alps. Otiz was carrying two small lumps of birch polypore on a goat-skin thong around his neck.  

Initially, some researchers put forth the idea that the fungus contains a laxative compound that Otzi was using to treat whipworms in his gut. While this sounds logical  and interesting, and spread quickly throughout the internet, other scientists found no cultural or experimental evidence that chemicals in the fungus have that particular effect.  

There are far more reliable reports in traditional medicine, especially in Europe, of birch polypore being used as an antimicrobial, anticancer, and anti-inflammatory agent. In Canada, a paper on Traditional Dene Medicine based on collaborative research with Indigenous knowledge holders, reports that the fungus was boiled into tea that could heal internal bleeding, ease heart pain, and more.  

Traditional medicine, like those examples, is based on Indigenous science. While Western science uses short-term experiments that generally test one thing at a time, Indigenous science is practiced using trial and error through centuries, and is integrated into daily living. The knowledge gained through Indigenous science is valid and valuable. It can lose significance when taken out of its cultural context, though, such as by anthropologists without the full picture or a game of telephone on the internet.  

While Indigenous science doesn’t need to be vetted by Western science to be valid, it often spurs research questions that lead to that outcome. In the case of birch polypore, pharmacological studies provide evidence for antiviral, anti-inflammatory, anticancer, neuroprotective, and immune tonic properties in the tea, and especially in an alcohol extraction of the fungus.

Of course, none of those experiments contain the cultural context of how to treat a patient with this medicine.   Birch polypores aren’t just used for internal medicine. Slices of the fungi have been used as band-aids with built in styptic properties by people in Great Britain.

Recently, this versatile fungus has proved useful for sharpening razors, polishing Swiss watches, soaking up sweat in hat bands, and by entomologists for mounting insects.   Insects who haven’t been killed and mounted yet, mites, and even white-tailed deer, also rely on birch polypore as a source of food. Fungi are high in protein.

The first time birch polypore caught my attention, it was because a deer had taken a nibble out of one right at my eye level in the Museum’s Wayside Wanderings Natural Play Area.  

The fungus is an active player in the food web as well. Birch polypore may infect a wound in a birch tree and then just hang out for years, held at bay by the tree’s immune system, until the tree is weakened by other factors. Then the fungus begins to spread and eventually contributes to killing the tree.  

As a brown rot fungi, birch polypore breaks down cellulose in the tree cells and turns it to sugar, but leaves the dark, woody lignin behind. According to Tim Adam’s PhD thesis, published the year I was born, wood being decomposed by birch polypore smells like green apples. Naturally I had to see for myself, so I set out on another hike, this time with a small folding saw in my pocket. Slicing a notch out of a birch trunk riddled with young polypores, I sniffed deeply. While the scent was a bit sour, I don’t believe I agree with Tim.

Still, he spurred curiosity that got me outside on a sunny day.   From laughter, to curiosity, to other forms of internal medicine, birch polypore is a common fungus with a lot to offer.   

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.   For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our exhibit: “The Northwoods ROCKS!” is open through mid-March. Our Fall Calendar of Events is ready for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.