Polyporus radicatus

October 3, 2022

Good evening, friends,

This week’s mushroom is the rooting polypore (Polyporus radicatus). I found this mushroom on Wednesday at the base of a dead ash tree, but diligent readers will remember it got a feature in the recap of the Both Bolete foray.  Why don’t we go ahead and give this peculiar polypore the spotlight feature it deserves.

When I first happened upon this mushroom, I thought “oh, boletes, sweet”. I was a little suspicious about my initial identification based on where they were growing, tucked into a nook at the base of a dead ash, but the shape seemed dead on. You can even see a little mammal took some bites out of the cap. However, when I saw the guttation on the caps of the mushroom, photographed below, I knew this was no ordinary bolete – although “ordinary” isn’t an appropriate adjective for any bolete. In fact, this wasn’t a bolete at all. It’s a polypore – like your turkey tails and chicken of the woods – that has evolved to have the same physical toadstool shape as a lot of the mushrooms we know and love. Now, I didn’t lick up this guttation like I did with the oak bracket, but I certainly pondered about all the interesting and untapped medicinal compounds teeming within those amber droplets.

I traced my hand ever so subtly down the velvety stipe toward the base, in an attempt to harvest this mushroom in its entirety, but was surprised when I had to keep digging deeper into the soil. That’s because this mushroom originates underground and extends to the surface with the black “rooting stem” (seen below). The subterranean stem is equal in length to the aboveground portion of the mushroom, if not longer. The species name radicatus, in Latinmeans “rooted” and refers to this distinguishing feature. It’s thought that the mushroom’s “root” originates from the dead tree root the fungus is digesting (the fungus is saprobic), but it could also be growing from a sclerotium (a compact mycelial mass that stores nutrients). 

The mushroom releases its spores through pores, as we would expect of a bolete, however the pores on P. radicatus aren’t limited to just the underside of the cap. The pores run from the margin of the cap all the way down the stipe before tapering off toward the base. A couple of similar species are the black footed polypores, like Cerioporus varius, but P. radicatus is larger and the black portion of this mushroom is entirely underground. P. radicatus fruits summer through fall and, up to this point, has only been found in North America east of the Rockies.

There wasn’t much information on whether this mushroom was edible or not, so I figured I’d undertake the research myself. There aren’t really any polypores that are gonna rough you up if you eat them, aside from Hapalopilus rutilans, so I wasn’t too concerned about toxicity here. I cut a few, one centimeter thick filets from the cap and let them sit on a hot cast iron for a minute or two on each side before popping them in my mouth. They were tasty, not much flavor, but they were juicy and the texture was smooth. If you jazz them up with some butter/oil and salt and pep they’d be that much more scrumptious. And if you don’t get this email next week then we know that you actually shouldn’t eat them. The ins and outs of citizen science.

Full moon on Sunday,

1) Kuo, M. (2019, November). Polyporus radicatus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/polyporus_radicatus.html
2) https://mdc.mo.gov/discover-nature/field-guide/rooting-polypore
3) https://www.inaturalist.org/taxa/204635-Polyporus-radicatus
4) https://www.jungledragon.com/image/65084/rooting_polypore_polyporus_radicatus.html