When: 2011-08-24

Collection location: Beaver Co., Pennsylvania, USA [Click for map]

Who: Bob Zuberbuhler (Bob Z)

No specimen available

This medium size mushroom was found in abundance on an open lawn. Veil remnants are seen around the cap rim, and the stalk below the ring is very wooly. I’m calling this Agaricus andrewii rather than A. campestris primarily because of the appearance of the ring, but don’t know whether this is valid. Would appreciate help.



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I am no expert on Agaricus andrewii…
By: Debbie Viess (amanitarita)
2011-08-24 16:56:44 CDT (-0400)

never having even heard the name before this, but Roger’s Mushrooms has a nice
description, as well as a comparison with campestris (with which it is apparently often confused):


In the above description, Agaricus andrewii was singled out (and as you also noticed) by its having a woolly to fibrillose stipe below the evanescent ring. other differences are apparently microscopic and perhaps more consistent, with andrewii having sparse marginal cystidia and campestris having none at all. The description also emphasizes a smoother, whiter cap with andrewii, but not sure how valid that is.

I also found it interesting while reading these two descriptions that contrary to general belief, Agaricus campestris CAN show faint yellowing at the stipe base (not a quality mentioned for andrewii), although several online sources claim that campestris doesn’t yellow. One of these sources actually shows a campestris with an indeed pure white cap (compared to its yellowing-cap Agaricus neighbors) but with an obviously yellowing base! Sometimes, we see what we expect or want to see, and ignore the actual evidence before our eyes.