Names (plural) in North American Boletes: Boletus fraternus AND Boletus rubellus
- Genus 2: Boletus
- Genus 3: Xercomus
- Species 2: fraternus
Tells: Bright yellow cap flesh slowly stains bluish-green, while stem flesh stains blue/green on top & orange by the base. Very deep yellow pores stain blue/green.
Other Information: Small (<2″) dark red cap fades to brick-red & often cracks w/age. Often-long yellow stem often has vertical lines (striations) at the top; darkens from orange-red spots going down; & turns brown where handled. Hard to distinguish from Hortib. campestris (Field Bolete). The main distinction is that rubellus’ cap cracks even more, and campestris has pure yellow stem flesh (not orange by the base) and lacks the striations at the stem’s apex. Likes grassy areas near oak & beech.
Science Notes: DNA testing merged B. fraternus into B. rubellus, and then moved the combination to a new genus called Hortiboletus.
Edibility: Good. (B. rubellus was listed as “unknown” in the field guides, but B. fraternus was known to be a good edible).
- NH4OH (Ammonia): No data.
- KOH: Cap flesh turns dull orange.
- FeSO4 (Iron Salts): Cap flesh turns olive-green.