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  • Writer's picturePam Owen

Fall ’shrooms: Identifying a red bolete mushroom

Updated: Aug 4, 2022

This fall, in finding some boletes that were being consumed by some mystery fungivore (see "On the Hunt for Fungivores"), I had found one small bolete still mostly intact and picked it for identification purposes.

The Boletaceae (Bolete) family is huge. Sources vary on how big, but the family has at least two dozen genera and more than 400 species, perhaps twice that many. These species are among the polypores — mushrooms whose caps have pores on the underside rather than gills. I checked several sources, starting with my two favorites for Virginia ‘shrooms — Mushrooms of West Virginia and the Central Appalachians, a printed guide, by William C. Roody, and, the website of mushroom expert Michael Kuo.

Although Kuo has much longer and in-depth descriptions of mushrooms, updates info on his website as needed, and even offers a key to help ID fungi, I often thumb through Roody’s printed guide first to narrow down the ID to at least the family before plunging into the deeper waters Kuo often navigates.

I like Kuo because he’s not afraid to get into the vagaries of mushroom ID and doesn’t seem compelled to provide definitive answers where there is doubt. Not being a mycologist and more just a budding fungus enthusiast, I often get lost in his long, sometimes highly technical, descriptions of species. Reading them reminds me of the one thing I’ve learned in my attempts at sorting out fungi: mushroom ID is hard.

Wisely, Kuo refrains from opining on which species are edible, as the disclaimer on his site’s homepage makes clear: “MushroomExpert.Com contains no information about the edibility or toxicity of mushrooms.” Being not nearly as knowledgeable as he, I also refrain from discussing edibility and also warn readers that I'm not an expert and am often just giving my best guess when it comes to specis ID.

Mushrooms are the reproductive organs of fungi, producing spores that are their “seeds.” For gilled and polypore mushrooms, the spores are in the underside of the caps. Experts often rely heavily on the visual aspects of a mushroom’s spores. If I wanted to eat wild mushrooms, I certainly would do whatever would be necessary to ensure I’m not poisoning myself. In fact, as I’ve written many times before, I will never eat a mushroom I’ve picked in the wild until I see an expert not only ID it but also eat one. I encourage newbie mushroom hunters to do the same. I haven’t taken that next step in identification . . . maybe next year?

With the help of Roody and Kuo, I narrowed the possible bolete species in question down to the three most promising: Sensitive Bolete (Boletus sensibilis), False Sensitive Bolete (Boletus pseudosensibilis), and Bicolor Bolete (Baorangia bicolor, formerly Boletus bicolor). The taxonomy of many species, not just fungi, has been evolving incredibly rapidly in recent decades, thanks to the ability to see similarities and differences among them down to the molecular level. Among the species that have been moved to another genus is the Bicolor Bolete, from Boletus to the genus Baorangia, following DNA research by a team of Chinese scientists in 2015. (Such changes have often not gone down well with some scientists, leading to some volatile discussions — public and private.)

All three bolete species mentioned above have caps that are reddish on top and yellow underneath, although they do have subtle variations. Beyond coloring, some sources note that the Sensitive Bolete also has a “curry” smell. Kuo, however, points to mistakes in descriptions of this species, including color and odor.

One way to sort out at least the False Sensitive Bolete from its lookalikes is to put a drop of ammonia on the cap surface, which will turn blue if the mushroom is the former. When I tried that test, the cap’s color did not change, so I ruled out that species.

Three photos of a bolete showing test marks for identification
The cap of the sample bolete, showing slug damage, before testing (left) and with testing marks

That left me with distinguishing the Sensitive from the Bicolor, both of which will stain blue when injured. But the Bicolor Bolete, according to Roody, stains “slowly and weakly blue,” while its cousin, the Sensitive Bolete, stains more quickly and darker, as its name implies. To check staining, I pressed my thumb into the spongy underside of the cap, then got a small metal skewer and carved hash marks near the print. I found the marks stained somewhere in between the speed and intensity described, so I still wasn't sure. So I turned to Roody’s description of the stalk — “rusty red or rosy red, yellow at the apex or sometimes nearly yellow overall” — and decided on the Bicolor, keeping in mind that mushroom identification is tricky and I could be wrong.

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