Observation 33980: Agaricus L.

When: 2010-02-22

Collection location: Greer Park, Palo Alto, California, USA [Click for map]

Who: Len (placeport)

No specimen available

Fruitbody type agaricoid, pileus flat, pileus width 100 – 160 mm, pileus surface with radial fibers, pileus color white to buff with some darker scales, pileus surface dry, stipe width 20 mm, even, with a small bulb at base, stipe colour whitish to cream, ring present, loosely attached, lamellae attachment free, hymenophore dull brown, lamellae crowded, fruitbody height 80 mm, color of spore print chocolate brown, substrate/habitat debris, turning darker but not yellowing when bruised or rubbed at base of stipe or margin of cap, smell very faintly phenolic (1 observer) or “like a store mushroom” (2 observers), stipe easily snaps clean off from cap. Seems too large for A. californicus (largest was 160 mm across cap), but somewhat more brown to buff than A. arvensis.


Natural light, overcast, diffuse, 4:30 p.m.

Proposed Names

-66% (6)
Recognized by sight: Found growing along side a path, in bark mulch and decaying leaves.
Used references: Mycokey; Trial Key to Common Agaricus Species
of the Central California Coast, By Fred Stevens
61% (3)
Recognized by sight

Please login to propose your own names and vote on existing names.

= Observer’s choice
= Current consensus


Add Comment
A. californicus a good guess
By: Rick Kerrigan (rwkerrigan)
2010-02-23 15:03:42 CST (-0500)

Except for the size and fringed cap margin, the features agree fairly well with a woodland collection of A. californicus. Notice the veil, particularly the thick margin. It might also be a related species (less is known about these), and a spore size measurement (calculate an average of 10-30 spores for L & W) is likely to be useful to help decide.

Less likely would be A. bisporus, which can have a similar annulus. Again, spore size data will be useful.

— Rick

Observed and photographed some more today
By: Len (placeport)
2010-02-23 00:27:44 CST (-0500)

Will see if I have time to test and report later…

Don’t know
By: Irene Andersson (irenea)
2010-02-22 11:22:30 CST (-0500)

what kind of Agaricus this is, but it doesn’t look like bitorquis. That’s a stubby mushroom with two separate rings.

Created: 2010-02-22 02:15:57 CST (-0500)
Last modified: 2011-02-28 12:16:23 CST (-0500)
Viewed: 82 times, last viewed: 2019-02-02 02:02:35 CST (-0500)
Show Log