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The Genus Agaricus

[ Basidiomycota > Agaricales > Agaricaceae > Agaricus . . . ]

by Michael Kuo

The mushrooms in Agaricus are terrestrial saprobes, and have caps that are not brightly colored. At maturity the gills are free or almost free from the stem, and are brown to chocolate brown. The stem breaks away cleanly from the cap—a fact known to anyone who has cleaned commercial "button mushrooms" from the store (Agaricus bisporus). Agaricus species have a partial veil which often forms a ring on the stem. The spore print is dark brown.

Identification of Agaricus species ranges from fairly easy to very difficult. Characters include bruising reactions of the cap, stem, and flesh--as well as odors and, occasionally, microscopic features. Rub the edge of an Agaricus cap repeatedly in order to assess whether it bruises yellow or not--and be sure to rub the base of the stem, as well. In some species the flesh inside the stem base turns yellow when sliced. Agaricus odors are particularly frustrating for me, since I am at least partially "smell blind" when it comes to one of the "distinctive" Agaricus odors: the "phenol" or "library paste" odor of some species. Other species smell like almonds (my sniffer registers this odor just fine), or have non-distinctive odors. Crush the flesh in the base of the stem to assess Agaricus odors.


Agaricus augustus

Agaricus bisporus

Agaricus spore print


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Kuo, M. (2017, November). The genus Agaricus. Retrieved from the MushroomExpert.Com Web site:

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