When: 2015-12-11

Collection location: El Dorado, California, USA [Click for map]


Who: Andrew S (AmatoxinAndy)

No specimen available

Found growing single in soil/leaf litter beneath a live oak, also in the immediate vicinity of a manzanita bush.

Cap: 12.5 cm x 9 cm diameter (widest points)
Stipe: 9 cm long
Stipe diameter: 2.5 cm at base, 8 cm at widest point (bulbous), 5 cm near cap

Cap a wine-red color predominantly, transitioning to more orangish tones toward margin. Irregular, undulating in shape with a smooth dry, surface (slightly viscous when found).

Context yellow, tubes yellow, stipe yellow. In cross-section, slight reddish tinges in stipe toward base. Context blues gradually when cut; tubes blue when cut.

Tube openings relatively obvious (on large side), possibly angular, random pattern. Sometimes tinged brown.

Spores were olive-brown and elongated ellipsoid in shape, the latter consistent with “fusoid” description for proposed ID.

2% iron sulfate solution applied to cap produced a color change to a darker but nondescript color; not inconsistent with expected purple but more blackish.

2% iron sulfate solution applied to context produced grayish color, consistent with proposed ID.

Specimen weighed 9.3 oz.


Irons sulfate test on cap. Syringe points to spot. Not exactly purple, but close
Underside demonstrates yellow tubes bruising blue; also consistent with angular pores
Cap slices (left) show pronounced blueing, esp. of tubes but also context; stipe cross-section bottom right demonstrates slight red in otherwise yellow stipe

Proposed Names

57% (1)
Recognized by sight: Under oak in the fall – too red for B. persolidus
Used references: http://davidarora.com/...

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= Observer’s choice
= Current consensus


Add Comment
Agreed, thank you.
By: Andrew S (AmatoxinAndy)
2015-12-14 06:18:21 PST (-0800)

Definitely not persolidus—flesh not as firm raw or cooked as my experience with B. persolidus—but I had applied another Butyriboletus species name (regius) that your Arora reference assigns to Europe. The B. querciregius description fits the specimen and circumstances exactly, thank you.