Observation 9935: Amanita frostiana (Peck) Sacc.
When: 2008-08-14
No herbarium specimen

Notes: Bright yellow color, warts atop cap, ring collapsed but persistent.

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Recognized by sight

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lack of persistent collar, striate margin
By: Andrew Reding (aareding)
2008-08-24 16:45:30 PDT (-0700)

According to
“With the exception of some localities, it [Amanita frostiana] is not commonly encountered; and the great majority of supposed collections of the present species are found to be wrongly determined material of Amanita flavoconia G. F. Atk. However, the latter species has ellipsoid, amyloid spores and no persistent collar of volval material at the top of the bulb.”

The illustration in the Peterson Guide (McKnight) shows a striate margin on Amanita flavoconia.

Well, this may be a rare occurrence…
By: R. E. Tulloss (ret)
2008-08-24 15:40:52 PDT (-0700)

Very often I have seen Amanita flavoconia labeled as A. frostiana. I think this may be the first time I am seeing the roles switched.

A view of the bulb and/or a shot of the gills (with a clear view of some representative short gills) could help in the present case. The striate cap margin should only show up in an old or depauperate (little and scrawny) specimen of A. flavoconia. But it’s standard in A. frostiana. The bulb in A. frostiana would suggest those of A. muscaria and/or A. pantherina. The short gills in A. frostiana are pretty much squarely cut off. Those in A. flavoconia do not terminate abruptly (except, maybe, for the very shortest ones). With Melzer’s reagent, the ellipsoid spores of A. flavoconia become dark; but the nearly round spores of A. frostiana do not. Maybe there will be another fruiting of the present species at the site of this observation. More pictures and/or a dried specimen would be interesting.

Very best,



Created: 2008-08-23 13:58:47 PDT (-0700)
Last modified: 2008-08-23 14:00:55 PDT (-0700)
Viewed: 103 times, last viewed: 2016-10-25 22:35:50 PDT (-0700)