Birch Polypore

Birch Polypore

Birch Polypore


Birch Polypore mushrooms (Fomitopsis betulina, formerly Piptoporus betulinus) are potent medicinals with a long history of human use. This easy to identify mushroom grows on birch trees and is relatively common anywhere birch are present.

Mature Birch Polypore

Humans have been using birch polypore mushrooms for a long time, and the earliest evidence of their use dates back 5,000 years.

The ancient body of a herder found buried in ice high in the Alps was recently unearthed with all his possessions perfectly preserved. He was carrying two mushrooms, Tinder Polypore (Fomes fomentarius) and Birch Polypore (Fomitopsis betulina). Neither mushroom is edible, but both a number of medicinal uses.

Birch polypore happens to be a great treatment for intestinal parasites (among other things), the very same type that was found mummified inside the ice man’s digestive tract.

While parasites are less of a concern for modern man, birch polypore also happens to be anti-bacterial, anti-viral, anti-inflammatory and immune-boosting. Those properties combined with its spongy texture make it an excellent field bandage, and modern extracts are used to combat disease as well.

Young Birch Polypore Mushrooms
Young Birch Polypore mushrooms breaking through the bark on a paper birch tree near my home in Vermont.

I’ve been hunting birch polypore mushrooms for a long time. Many years in fact.

Every year I find a few traces, moldy mushrooms past prime, and large pristine specimens high up out of reach.

They are common, almost as common as birch trees, but it can be tricky to find harvestable birch polypore mushrooms within reach.

Birch Polypore Mushrooms Past Prime
Small birch polypore mushrooms in poor condition, already well past prime.

Fomitopsis betulina is a parasite of birch, and it attacks trees that have been weakened by disease, overcrowding or injury. It’ll often start at some vulnerable or damaged portion of the trees crown. From there it’ll work it’s way down to the trunk, slowly killing the tree in the process.

It’s sometimes easiest to spot birch polypore on the forest floor, as the infected branches break and drop during storms. Once you’ve found an infected tree, keep an eye on it. It’ll be a source of the fungus until it’s eventually killed by it, and then still long after as the Birch polypore also consumes deadwood.

Within a few years of the first dropped branches, watch for eruptions all along the trunk as the fungus progresses and provides harvestable mushrooms lower down.

With enough patience, one of the trees I’ve been watching has finally started producing along its reachable trunk, and all of a sudden I was able to harvest them by the bucket load.

Old Birch Polypore Mushrooms
Birch polypore grows primarily on birch trees, and has no look-alikes.

Still, what the author of a mushroom book considers a “look-alike” is often very different than what a novice in the field optimistically hopes is the mushroom that’ll fulfill their quest.

Be sure to double-check with multiple sources, as always, when identifying any mushroom.

Birch Polypore Mushroom in Profile
Generally, birch polypore mushrooms are kidney-shaped or semi-circular. Sometimes they’re directly attached to the tree with no stalk, and other times they have a short narrow stalk before widening out.

Young birch polypores can be a bit more round as they’re just bursting through the tree bark.

Young Birch Polypore
Their surface varies from white to grey to brown, and various light-colored shades in between. Most that I’ve seen have had a tan-ish hue on the top side.

The pore surface is covered by very tiny pores that are just barely visible, and it’s usually white to grey in color.

Birch Polypore Underside
Birch polypore mushroom pore surface

The outer ridge of the pore surface is often rounded, with a slightly raised lip right along the edge.

Their shapes can vary quite a bit in the field though, so this is all only rough guidance.

Birch Polypore Edge
Ridge at the edge of the pore surface of a birch polypore mushroom

Generally, a spore print is used to identify mushrooms, but it won’t help you much here. Birch polypore’s spores are tightly bound within the pore surface and it won’t give them up until long after it’s useful to harvest.

Still, the spore print is white in case yours happens to be giving up its spores conveniently for printing.

The mushrooms themselves are incredibly lightweight, and it almost feels like you’re holding styrofoam brick. Cut one in half and you’ll find a dry, spongy texture that’s not all that different than styrofoam too.

They’re usually white or off white on the inside.

Birch Polypore Interior
While birch polypore has been used in folk medicine for thousands of years, how does it stand up to modern scientific testing? Pretty well actually.

According to one peer-reviewed study,

“Modern research confirms the health-promoting benefits of F. betulina. Pharmacological studies have provided evidence supporting the antibacterial, anti-parasitic, antiviral, anti-inflammatory, anticancer, neuroprotective, and immunomodulating activities of F. betulina preparations. Biologically active compounds such as triterpenoids have been isolated. The mushroom is also a reservoir of valuable enzymes and other substances…. In conclusion, F. betulina can be considered as a promising source for the development of new products for healthcare and other biotechnological uses.”

Birch Polypore on Standing Dead
Though it’s not considered strictly “edible” because it’s about the same as eating styrofoam, birch polypore is generally dried for tea or made into an alcohol extract (tincture).

The same strange texture that makes it difficult to consume actually makes it a pretty good wound dressing. According to The Mushroom Hunter,

“By digging out strips of the flesh just beneath the pore surface of the mushroom, the birch polypore can be used as a safe, clean, blood stanching, anti-inflammatory bandage or wrap over cuts sustained while hiking in the woods.”

Beyond Birch polypore’s medicinal uses, it also has other practical uses in the field. It goes by the alternate name “razor strop fungus” because historically it was used to hone blades to razor sharpness (and maintain the edge on a blade). While it won’t sharpen a dull blade, families that couldn’t afford leather would seek out these mushrooms for use as sharpening strops.

Lastly, dried birch polypore can be used as tinder for fire-starting. The dried mushroom will accept sparks readily, allowing you to start a fire when other dry tinder is hard to come by. Historically, it was used to transport fire, since once lit, birch polypore will smolder for hours if not days.

This demo explains the process neatly:

Birch trees actually grow a number of types of mushrooms that can be used for tinder. The most well known is actually called Tinder Mushroom or Tinder Polypore (Fomes fomentarius), and I’ve often seen it growing in mass right alongside Birch polypore.