Western Jack-o'-lantern Mushroom

Omphalotus olivascens, commonly known as the western jack-o'-lantern mushroom, is an orange to brown-colored gilled mushroom native to California and Mexico. To an untrained eye, O. olivascens appears similar to some chanterelles, but unlike the chanterelle, the jack o'lantern mushroom is poisonous. While not lethal, consuming this mushroom leads to very severe cramps, vomiting, and diarrhea.

Unlike chanterelles, the jack-o'-lantern mushroom has true gills (rather than ridges) and it can have olive coloration that chanterelles lack; also, Omphalotus species are saprotrophic, grow directly on wood, and are bioluminescent.

A subspecies with blue flesh, O. olivascens var. indigo, was described growing on live oak in Baja California, Mexico.

A recent molecular study shows the jack-o'-Lantern to be most closely related the Ghost Fungus Omphalotus nidiformis.