Name in North American Boletes: Boletus pulverulentus
- Genus 2: Boletus
- Genus 3: Xercomus
Tells: Quick-bluing stem flesh is yellow high & brown at the base. Yellow pores and stem (gets redder going down) bruise blue but resolve to brown.
Other Information: Variable-color cap instantly stains blackish blue & usually has a dust or powder on its surface. Yellow cap flesh stains straight blue. White mycelium darkens to brown when handled. Stem often has raised ridges but not true reticulation.
Science Notes: DNA testing moved this mushroom from Boletus to a newly erected genus called “cyanodoboletus” (“cyano” referring to the characteristically brilliant blue stains). The parenthesis are there on the name because pulverulentus is a European name, DNA has proven the American lookalike is a different species, but the replacement North American name has yet to be adopted.
Edibility: Good. But it should be noted that at least one European paper has reported their lookalike to be a hyperaccumulator of arsenic, which would reduce the rating there to no better than “iffy.” No similar study has been conducted in North America.
- NH4OH (Ammonia): Cap surface flashes green. Blued flesh loses its staining.
- KOH: According to Mushroom Expert, the cap skin turns black and stained flesh turns orangish.
- FeSO4 (Iron Salts): According to Mushroom Expert, the cap skin has no reaction but the blued flesh loses its staining.