About
Fomitopsis betulina, commonly known as the Birch Polypore or Razor Strop Fungus, is a bracket fungus that exclusively grows on birch trees. Recognized for its smooth white cap and leathery texture, it has a long history of use in traditional medicine, wilderness survival, and even tool sharpening. While inedible in a culinary sense, it is highly regarded for its antibacterial, anti-inflammatory, and immune-boosting properties.
History
The Birch Polypore has been utilized since ancient times. Notably, it was found among the belongings of Ötzi the Iceman, a 5,000-year-old mummy discovered in the Alps. It is believed he used it for both medicinal purposes and as a fire-starting aid. Historically, barbers and craftsmen used dried slices of the fungus as a leather-like strop to sharpen razors and knives—hence the nickname "Razor Strop Fungus."
In folk medicine, it has been brewed as a tea to treat gastrointestinal issues, parasitic infections, and inflammation.
Overview
F. betulina produces hoof-shaped, shelf-like fruiting bodies with a smooth, white to gray cap and a porous underside. It typically grows in clusters on dead or dying birch trees and plays a key ecological role in decomposing hardwoods.
It is harvested, dried, and often made into tinctures, teas, or powdered supplements. Active compounds include betulinic acid, agaric acid, and triterpenes, which show potential antiviral and antimicrobial activity. It is not used culinarily due to its tough, corky texture, but it remains a staple in herbal and survivalist practices.
Physical Characteristics
Caps:
The cap of Fomitopsis betulina is typically kidney-shaped or semicircular, with a velvety texture and a reddish-brown to black color.
Gills:
This mushroom does not have gills as it is a polypore fungus.
Helps With
Cardiovascular Support
Fomitopsis betulina is known for its immune-boosting properties and may help support overall immune function.
Inflammation
Studies suggest that Fomitopsis betulina may have anti-inflammatory effects, potentially benefiting conditions related to inflammation.
Oxidative Stress
The antioxidants present in Fomitopsis betulina may help protect cells from damage caused by free radicals.
Medicinal Chemistry
Similar Species

Species: Fomitopsis pinicola
Edibility: Fomitopsis pinicola is also not recommended for consumption.
Key Differences: The main difference between the two species is their host trees and habitat.

Species: Fomitopsis pinicola
Edibility: Fomitopsis pinicola is also not recommended for consumption.
Mushroom Ratings
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01/29/2025
Noah Schlickeisen
01/29/2025
Josh Shearer