Basionym: Agaricus applanatus Pers., Observationes mycologicae 1: 8 (1796) [MB#204744] Obligate synonyms: - Agaricus planus Pers., Synopsis methodica fungorum: 480 (1801) [MB#243694] - Crepidotus applanatus var. applanatus (?) [MB#422979] Taxonomic synonyms: - Agaricus putrigenus Berk. & M.A. Curtis, Annals and Magazine of Natural History 4: 292 (1859) [MB#463399] - Crepidotus putrigenus (Berk. & M.A. Curtis) Peck, Annual Report on the New York State Museum of Natural History 39: 72 (1886) [MB#206475]