Voodoo Mycology (Part I)

What do we have here -- X. subtomentosus? X. spadiceus?

How do you tell apart the various species in Genus/Subgenus  Xerocomus -- well, when all else fails, let's do some macrochemical testing...

Ammonia Reaction (NaOH4 20%)

The pilleus turns blue when encountering the ammonia vapor, then quickly goes to red (which is a banal reaction of ammonia with many mushrooms).

Wow, that means that we have X. spadiceus (sensu Thiers, Baroni, Singer, etc.)

Contemporary studies seem to raise doubts about this method of determining X. spadiceus...