The genus Leucocoprinus in western Washington

The genus Leucocoprinus in Washington state was investigated based on fresh and herbarium collections as a part of a survey to assess the biodiversity and abundance of all lepiotaceous (Agaricaceae) fungi in the Pacific Northwest. Seven species were found to occur in the study area. Leucocoprinus (Lc.)flavescens is reported from Washington while Lc. brebissonii and Lc. heinemannii are credibly recorded in North America for the first time. The complex history of Lc. cretaceus in North America including its first record from Washington is discussed. The above four species as well as Lc. birnbaumii, Lc. cepistipes, and Lc. ianthinus are described and their microscopic characters illustrated.