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Dianna Smith (2003-2016) / Peter Russell (2012-2013) | all galleries >> MUSHROOM WALKS, EVENTS & FORAYS 2004 >> Fahnestock State Park 08 07 04 > Boletus edulis (or Xanthoconium separans!*)
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07-AUG-2004 Dianna Smith

Boletus edulis (or Xanthoconium separans!*)

These prized choice edibles were brought in by Chuck for identification. The specimens above, although actually quite young and small, exhibit typical edulis characteristics: a reddish-brown 'bun' cap, tiny white rounded pores, a bulbous stalk that widens toward the base, white reticulation on upper stalk and darker reticulation (webbing) on the lower 2/3rds.

*Steve Rock and Mark Debellis, who both know far more than I about members of the Bolete family, suggest that the specimens in the photo above are actually Xanthoconium separans (also known as Boletus separans).(See Steve's note below). I think they may be right. This just goes to show you that it is not easy, even following keys, to determine the correct identity of any particular mushroom. Fortunately, in this case, Mark at least believes that Xanthoconium separans is as good as - if not tastier than Boletus edulis. Because I don't have the original specimens I am unable to perform a simple chemical test to definitively determine the exact identy of the mushroom. But my inclination is to defer to their collective wisdom!

For more information on Xanthocaonium separans go to www.bluewillowpages.com/mushroomexpert/xanthoconium_separans.htmlhe

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Mitchell Nuhn 29-Jan-2013 22:48
That is most definitely Xanthoconium separans.

Mitchell Nuhn
PhD Grad Student
Department of Biology
Clark University
Guest 06-Jun-2007 15:08
Hello,
I noticed the image of the two boletes from 2004 on your Web site, and agree with Xanthaconium separans ID. A simple drop of ammonia on the stem instantly changes its color to a pretty turquiose. Also, if you were to split open the stem (or squeeze it), you should notice a pithy, almost hollow interior, especially in age. I my observations of the species here in southern Illinois, the net-like reticulation on the stem can be quite variable: on the upper or lower portion only, or both, or none visible at all. Also, in comparison to Boletus edulis (which is almost nonexistent in Illinois), the flesh in the cap of Xanthaconium separans isn't as thick as it is in B. edulis. That is, the tube layer under the meaty part of the cap in X. separans is bigger than the adjoining meaty part. For those purists who cut away the tube portion of the cap before cooking, it leaves a rather thin strip of "meat" left on the cap.
I am not a myophagist who carries little bottles of reagents into the field, and so the ammonia test I mentioned is always done when I return. But since many kitchens or laundry rooms have a bottle of ammonia stashed someplace, confidently identifying X. separans is rather easy. That instant color change tells the story.
Thanks for the nice web site.
Joe McFarland
Illinois Department of Natural Resources
Steve 12-Aug-2004 19:04
With those pinkish hues, Mark and I think this is actually Xanthconium seperans.