Observation 199482: Amanita ocreata Peck

When: 2015-02-21

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

Who: Andrew S (AmatoxinAndy)

No specimen available

Growing nearby my similar observation from 2-20-15: in soil, in grove of live oak trees with some blue oak nearby.

These specimens more clearly show annulus (smaller specimen) and remains of an annulus (larger specimen) than prior day’s specimen, with additional partial veil remnants under cap of larger specimen.

Very obvious sac-like volva on both, with expanded stipe toward base.

Caps white/off-white, dry, with no reddish area in middle of cap as prior day’s specimens believe to be same species. Gills, stipe, volva all white.

No remarkable odor.

Obvious and rapid yellow color development upon application of 4% KOH to slice of pileus.


Slices from larger specimen treated with 4% KOH (left) or water (right), adjacent to smaller specimen

Proposed Names

54% (1)
Recognized by sight
Based on chemical features

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Add Comment
how best to dry?
By: Andrew S (AmatoxinAndy)
2015-02-21 18:33:16 CST (-0500)

Hi Rod,
Thanks; it’s a pleasure to have something objective to show…

I haven’t dried specimens to date but would be happy to try for your collection. If you can give me a few basic tips on best practices, I can start the process on these.


Hello, Andrew.
By: R. E. Tulloss (ret)
2015-02-21 18:07:46 CST (-0500)

It’s nice to post images of ocreata showing the yellowing reaction with KOH. Thanks. Do you ever collect material and dry it for later work? I’m interested in collecting A. ocreata from a variety of different locations to in order make comparisons between the collections.

Very best,

Rod Tulloss