When: 2000-09-02

Collection location: Larkspur, California, USA [Click for map]

Who: Ron Pastorino (Ronpast)

No specimen available

These were found growing under planted Birch in 2000 but haven’t seem them since.
Did not save them but managed to scrape off some spores from a print I had made and check them under a scope. Spore print brown to sl. olive brown.
The spores were fairly wide, ~ 12.2-14.1 X 6.0-7.0 microns.
Earlier Darv suggested Xerocomus rubellus and that seemed the closet North American match although Birch is not their normal host. The Bessette book notes spores for Boletus(Xerocomus) rubellus @ 10-13 X 4-5 microns. That’s smaller than this collection.
Since I’ve been finding European species under these Birches, I wonder if there is a European species these might match?


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Xerocomus rubellus may be back in the running
By: Ron Pastorino (Ronpast)
2011-09-29 18:59:42 CDT (-0400)

after coming across this European description…

The spore size is a closer fit as well as the color of the cap flesh.
I also noticed that “Xerocomus” as a genus is in trouble for many reasons.

My notes indicate that the pores
By: Ron Pastorino (Ronpast)
2011-09-29 18:11:25 CDT (-0400)

did go through a transitory initial bluing and I think fairly rapidly to a dirty dull blue, then brown as the photo indicates.
The flesh did not appear to blue significantly, or if it did it would have been an even faster transition. My notes also described the flesh as v. light yellow, not the “bright yellow” that is noted in the BRB book.

other than that off spore size…
By: Debbie Viess (amanitarita)
2011-09-29 12:22:04 CDT (-0400)

the macro description for rubellus sure fits this collection. did it blue, then turn brown on the pores?

I can also sorta see the punctate effect on the stipe, at max mag, as is described for rubellus in the BBB of Bs.