Observation 74058: Tylopilus ferrugineus (Frost) Singer
When: 2011-08-15
No herbarium specimen

Notes: An adorable caespitose family of a Tylopilus species growing in the shade of a small pure stand of oak trees made me smile on a rainy and cool afternoon in the Poconos. I left the happy familiy untouched and instead collected what appeared to be conjoined fungal twins fused to form a single peculiarly shaped basidiocarp that I christened “fat boy” [Tylopilus is a masculine name after all]. :-)
This is a mild tasting larva-free bolete with a very pleasant sweet fungal odor. The stipe is brownish on the bottom half, whitish at the top with a narrow band of prominent white reticulation at the apex. The context is whitish, staining pinkish-brown almost immediately upon oxidation (the color intensity reached its peak several minutes following exposure to air). The dark brown pileus, lacking purplish tones and margin chamfering, together with the context staining pale yellow with application of KOH (aq) seem to eliminate T. badiceps and, to a lesser extent, T. indecisus, though now I am beginning to distrust the KOH-on-context test in light of the personal experience with species of this type as well as obs. #73673). I find the poorly matching results of macrochemical tests on the pileipellis to be less reliable because they were conducted after a substantial delay and excessive handling.

Proposed Names

60% (2)
Eye3 Eyes3
Recognized by sight: A mild tasting Tylopilus species from the badiceps-ferrugineus-indecisus cluster
Based on chemical features: 3% KOH staining the context pale yellow
28% (1)
Used references: Input from Bill Yule

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
A tough group to distingish for many reasons: badiceps, ferrugineus, indecicus,
By: Bill (boletebill)
2011-08-17 16:29:22 PDT (-0700)

but as you say all edible. i too have a healthy skepticism about the published chemical test for boletes and I find mixed results and often contradictory results, but sometimes good information. I’m very skeptical of the description reticulate at the apex for bolotes. Who knows what this really means?? In my experience most boletes, especially Boletus and Tylopilus(except those with depressed tubes) can sometimes have a slight reticulation at the apex WHEN THE CAP IS FULLY EXPANDED. This is a remnant of the tube walls pulling away from the stipe apex as the cap expanded. To me this isn’t a real reticulation it’s a bit of left behind tube wall. I did fing Tylopilus ferrugieus today on my way home from work and I’ll post it.

Ferrugineus vs. indecisus
By: I. G. Safonov (IGSafonov)
2011-08-17 11:55:04 PDT (-0700)

Bill, thank you for your input. I have no problem accepting your ID proposal based on the stated facts; besides I cannot argue with the vast field experience you’ve amassed over many, many years. Furthermore, as I mentioned above, I am beginning to grow a bit distrustful of the KOH-on-context test because every time I collect this kind of a Tylopilus species, the test would always be positive. As far as the reticulation is concerned (you can clearly see it in the third picture from the top if you blow it up), the big bolete book does mention reticulation in T. ferrigineus at the stipal apex or the upper half; however, the corresponding picture in the book shows what appeares to be a glabrous, all-brown stipe. Identification aside, fortunately these three species of Tylopilus are edible, and dried slices of “fat boy” will wind up in a soup one day. :-)

Never have seen T. ferrugineus with prominent reticulation
By: Bill (boletebill)
2011-08-17 11:19:24 PDT (-0700)

Without information about chemical reactions I would assume this to be T. indecicus, an oak lover that always has reticulation and a white portion on the upper third of the stipe. In my experience ferrugineus has a stipe concolous with the cap over it’s whole length and no reticulation.

Created: 2011-08-16 18:35:05 PDT (-0700)
Last modified: 2013-05-24 11:10:07 PDT (-0700)
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