The Agaricus Challenge -- 3 common Agaricus species, fruiting on the same lawn at the same time. Can you tell them apart?
Agaricus xanthodermus L quick yellow, phenolic odor
Agaricus campestris C no yellowing, regular odor
Agaricus arvensis R quick yellow, pleasant odor

Agaricus abruptibulbus                                                                                                         [more]

Agaricus aestivalis (Mųller) Pilįt     European collection under Picea abies. Very similar to A. silvicola, but with distinctly elongated spores.

Spores: 7.2-8.3 (9) x 4-4.5

Agaricus albolutescens   (California) Frequent in Sierra Nevada (Spring)  -- it is not exactly a snowbank species, but occurs soon (2-4 weeks) after the snow has melted in the area. Very similar in odor and yellowing effect to A. silvicola, but has significantly larger spores.

6-7.2 (7.8) x 4.1-5µ

Agaricus arvensis                                                                       [more]

Agaricus augustus                                                                     [more]

Agaricus benesii            
(California)                                              [more]

Agaricus bisporus                                                [more]

Agaricus bitorquis    (California)                                                                                  [more]

Agaricus campestris var. campestris

Agaricus campestris var. squamulosus

Agaricus comtulus    (Bulgaria)                                                                          [more]

Agaricus cupreo-brunneus

Agaricus diminutivus                                                                      [more]

Agaricus fusco-fibrillosus    (California)

Agaricus fuscovelatus                                                                                     [more]

Agaricus hondensis                                                                                       

Agaricus lilaceps                                                                                                [more]

Agaricus osecanus                                                                                            [more]

Agaricus praeclaresquamosus                             

Agaricus semotus                                                                                           [more]

Agaricus silvaticus                                                                                          

Agaricus silvicola                                                                                                 [more]

Agaricus subrutillescens    (California)                                              [more]

Agaricus xanthodermus var. xanthodermus                           [more]

Agaricus xanthodermus var. lepiotoides                                   [more]

Probably Undescribed

Relatively smaller spores. 5.4-6x4-4.5μ
Agaricus a1     Sierra Nevada (Spring) -- an undescribed, snowbank Agaricus that has an intense deep yellow discoloration, but lacks the anise odor of the arvensis/silvicola species. Nor does it have the pungent odor of the Xanthodermati. It has relatively smaller spores. 5.4-6x4-4.5μ