Collection Data: Northeastern North America, mixed forest including birch species, hemlock, beech, pines. Close to riverfront, wet, acidic soil. Late summer. Growing singly, terrestrially.
It is characteristic of boletes to have specific mycorrhizal tree partners which can inform you on where to find them. In summer, I quickly discovered that birch and aspen in the forests around me sported bolete friends from the Boletus and Leccinum genera. This bolete, like some others, bruises blue; but as you can see, I was startled to find that a few minutes after I had broken the young specimen's stem, it looked as though it were bleeding. This two-color bruising was highly unusual for what I knew of Bolete color changing at the time. I have since returned and edited this post because I had previously identified this as Leccinum scabrum- but after I had a more seasoned ID expert from NAMA (North American Mycological Association) give it a closer look, I was informed this is L. snelli. After my own digging, I found out that this species is almost indistinguishable from another species that also exists in the Northeast, Leccinum variicolor- microscopic inspection of the cap surface (the pileipellis) is needed to tell them apart. Both these species bruise pink/red higher up on the stem and bruise blue/green lower down. The colorful molecule in question, variegatic acid, is capable of being converted to forms that account for both the red and blue I observed. A great thanks to Tom Volk for elucidating this information for me!
In the presence of oxygen, variegatic acid undergoes an oxidation reaction that produces the quinone methide, responsible for the blueing. Another closely related form, apparently also a result of oxidation, is variegatorubin, responsible for the red color.
The boletes are an incredible lesson in using bruising as an identification aid, and it was definitely a bucket list item of mine. Happy hunting!
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