amanita phalloides, commonly known as the "death cap", is a deadly poisonous fungus, one of many in the genus "amanita". widely distributed across europe, "a. phalloides" forms ectomycorrhizas with various broadleaved trees. in some cases, death cap has been accidentally introduced to new regions with the cultivation of non-native species of oak, chestnut, and pine. the large fruiting bodies (mushrooms) appear in summer and autumn; the caps are generally greenish in color, with a white stipe (stem) and gills (underneath the cap).