Species: borealis (North) or smithii (South)
- Species (Old): castaneus
Common Name: “Chestnut Bolete”
Tells: Stem stuffed with “cotton” & hollow when old. Flesh is hard and brittle. Brown cap edges often split & flare w/age.
Science Notes: DNA evidence has divided the classic European species (G. castaneus) away from its two lookalike American versions, G. borealis (which grows in northern regions) and G. smithii (which grows to the south). There is, of course, a massive area of overlap where both species grow.
- NH4OH (Ammonia): Cap skin turns amber-orange. Cap flesh may turn pale brown, but not reliably.
- KOH: Cap skin may be negative or may turn yellow before fading to white. Cap flesh may turn pale brown, but not reliably.
- FeSO4 (Iron Salts): Cap skin does not react. Cap flesh may turn pale brown, but not reliably.