Omphalotus olivascens

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Omphalotus olivascens
Omphalotus olivascens 125218.jpg
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Marasmiaceae
Genus: Omphalotus
Species: O. olivascens
Binomial name
Omphalotus olivascens
H.E.Bigelow, O.K.Mill. & Thiers (1976)
Omphalotus olivascens
View the Mycomorphbox template that generates the following list
Mycological characteristics
gills on hymenium
cap is infundibuliform
hymenium is decurrent
stipe is bare
spore print is yellow
ecology is saprotrophic
edibility: poisonous

Omphalotus olivascens, commonly known as the western jack-o'-lantern mushroom, is an orange to brown-colored gilled mushroom native to California and Mexico.


The fungus was described as new to science in 1976 by American mycologists Howard E. Bigelow, Orson K. Miller, Jr., and Harry D. Thiers.[1] A subspecies with blue flesh, O. olivascens var. indigo, was described growing on live oak in Baja California, Mexico.[2]

Several Omphalotus species with similar bioluminescent properties occur worldwide, all of which are presumed poisonous. The best known are the North American jack o'lantern mushroom (O. olearius) and the tsukiyotake (O. japonicus (Kawam.) Kirchm. & O.K. Mill. (formerly known as Lampteromyces japonicus (Kawam.) Sing.), found in Japan and eastern Asia. Molecular analysis shows the jack-o'-Lantern to be most closely related the ghost fungus Omphalotus nidiformis.[3] Miller notes that the colours and shades of the ghost fungus most closely resemble this species.[4]


To an untrained eye, O. olivascens appears similar to some chanterelles, but unlike the chanterelle, 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.[5]


A saprobe or parasite, O. nidiformis is nonspecific in its needs and is compatible with a wide variety of hosts.

Omphalotus species cause a white rot by breaking down lignin in their tree hosts.[3]


The jack o'lantern mushroom is poisonous; while not lethal, consuming this mushroom leads to very severe cramps, vomiting, and diarrhea.[5]

The toxic ingredient of many species of Omphalotus is a sesquiterpene compound known as illudin S.[6] This, along with illudin M, have been identified in O. nidiformis. The two illudins are common to the genus Omphalotus and not found in any other basidiomycete mushroom.[7]

See also[edit]


  1. ^ Bigelow HE, Miller OK Jr, Thiers HD (1976). "A new species of Omphalotus". Mycotaxon. 3 (3): 363–372. 
  2. ^ Moreno G, Esteve-Raventós F, Pöder R, Ayala N (1993). "Omphalotus olivascens var. indigo, var. nov. from Baja California (Mexico)". Mycotaxon. 48: 217–22. 
  3. ^ a b Kirchmair M, Morandell S, Stolz D, Pöder R (2004). "Phylogeny of the genus Omphalotus based on nuclear ribosomal DNA-sequences". Mycologia. 96 (6): 1253–1260. doi:10.2307/3762142. PMID 21148949. 
  4. ^ Miller OK. Jr. (1994). "Observations on the genus Omphalotus in Australia". Mycologia Helvetica. 6 (2): 91–100. 
  5. ^ a b Michael Wood & Fred Stevens. "Omphalotus olivascens". California Fungi. Retrieved 2011-03-25. 
  6. ^ Benjamin DR (1995). Mushrooms: Poisons and Panaceas — A Handbook for Naturalists, Mycologists and Physicians. New York, New York: WH Freeman and Company. pp. 366–67. ISBN 0-7167-2600-9. 
  7. ^ Kirchmair, Martin (1999). "Identification of illudins in Omphalotus nidiformis and Omphalotus olivascens var. indigo by column liquid chromatography–atmospheric pressure chemical ionization tandem mass spectrometry". Journal of Chromatography A. 832 (1–2): 247–52. doi:10.1016/s0021-9673(98)00892-9. ISSN 0021-9673. 

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