 By the end of the 19th century , Charles Horton Peck had reported A. phalloides in North America . In 1918 , samples from the eastern United States were identified as being a distinct though similar species , A. brunnescens , by G. F. Atkinson of Cornell University . By the 1970s , it had become clear that A. phalloides does occur in the United States , apparently having been introduced from Europe alongside chestnuts , with populations on the West and East Coasts . Although a 2006 historical review concluded the East Coast populations were introduced , the origins of the West Coast populations remained unclear , due to scant historical records . A 2009 genetic study provided strong evidence for the introduced status of the fungus on the west coast of North America . 
