Omphalotus is a genus of basidiomycete mushroom formally circumscribed by Victor Fayod in 1889. Members have the traditional cap and stem toadstool form. They are saprobic, and fruit in clumps on trees. The best known and type species is the jack-o'-lantern mushroom (Omphalotus olearius). Species of Omphalotus have been mistaken for chanterelles. All Omphalotus species are presumed poisonous, causing gastrointestinal symptoms. Some Omphalotus species have bioluminescent properties.