Day 38: Once upon a time, this mushroom was a Suillus. Field guides separated Suillus from Boletus by the shape of the pores on the underside, i.e., Boletus had small round pores and Suillus had open, irregular pores. It was easy to remember (and of course we like that), but then the scientists took a closer look at the dividing line between the two genuses and decided that pore shape wasn't an accurate indicator. Many of the species formerly placed in Suillus were shifted into Boletus as a result. This particular 'shroom was one of the victims of taxonomic flux, and I had to reset my head to accept the new nomenclature.
Science is always moving forward. Advances in technology put DNA sampling within the reach of more professionals, and suddenly the poor botanist would tuck in at night with one species name, only to find that it had changed by morning. The phenomenon wasn't limited to species. Whole new genera were created when DNA revealed that some species we thought of as siblings turned out to be fourth cousins by marriage three times removed. It was as if we discovered that our old friend Mary Smith's brother John was really her grandfather's ex-wife's nephew's daughter's husband. The family tree hadn't just been pruned; it had been cut back to the base and was growing into a many-branched bush.
Yesterday, I had to unlearn this mushroom again. Fortunately its distinguishing visible cues haven't changed, although you do have to use a microscope for the final analysis. As far as this one is concerned, you can line out "Suillus" or "Boletus" in those old field guides. Under its new nomenclature, Xerocomellus chrysenteron can be identified by its cracked, tomentose (velvety) cap, its red-tinged stipe base, its irregularly-shaped open pores, its tendency to bruise blue, and lastly, the telling oval spores which differ from the blunt-ended (truncate) spores of X. truncatus.
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