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

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

native to

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Taxonomy

The fungus was described as new to science in 1976 by American mycologists

Howard E. Bigelow Howard Elson Bigelow (June 28, 1923 – November 21, 1987) was an American mycologist, born in 1923 in Greenfield, Massachusetts, and died in 1987. He studied at Oberlin College from 1941 to 1943. He left college to fight in the American army. He ...

, Orson K. Miller Jr., and

Harry D. Thiers Harry Delbert Thiers (January 22, 1919 in Fort McKavett, Texas – August 8, 2000 in Ohio) was an American mycologist who studied and named many fungi native to North America, particularly California. Thiers taught mycology at San Francisco St ...

. A subspecies with blue

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscle Skeletal muscles (commonly referred to as mu ...

, ''O. olivascens'' var. ''indigo'', was described growing on

live oak Live oak or evergreen oak is any of a number of oaks in several different sections of the genus ''Quercus'' that share the characteristic of evergreen foliage. These oaks are not more closely related to each other than they are to other oaks. ...

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, Mexico.

Description

To an untrained eye, ''O. olivascens'' appears similar to some

chanterelle Chanterelle is the common name of several species of fungi in the genera '' Cantharellus'', '' Craterellus'', '' Gomphus'', and ''Polyozellus''. They are among the most popular of wild edible mushrooms. They are orange, yellow or white, meaty a ...

s, but unlike the chanterelle, the jack-o'-lantern mushroom has true, blade-like

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

(rather than ridges) and it can have olive coloration that chanterelles lack; also, ''Omphalotus'' species are

saprotrophic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...

, grow directly on wood, and are

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

. The cap is wide. The stalks are long and wide. The spores are white to pale yellow.

Ecology

saprobe Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

, ''O. nidiformis'' is nonspecific in its needs and is compatible with a wide variety of

hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ( ...

. ''Omphalotus'' species cause a

white rot A wood-decay or xylophagous fungus is any species of fungus that digests moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as ''Armillaria'' (honey fungus), are parasitic and col ...

by breaking down

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...

in their tree hosts.

Biochemistry

The jack o'lantern mushroom is

poisonous Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...

; while not lethal, consuming this mushroom leads to very severe

cramp A cramp is a sudden, involuntary, painful skeletal muscle contraction or overshortening associated with electrical activity; while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the aff ...

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose. Vomiting can be the result of ailments like Food-poisoning, foo ...

, and

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

. The toxic ingredient of many species of ''Omphalotus'' is a

sesquiterpene Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificatio ...

compound known as

illudin The illudins are a family of sesquiterpenes with antitumor antibiotic properties produced by some mushrooms. In their isolated form, illudins show selective toxicity for myelocytic leukemia and other carcinoma cells. Illudins are highly toxic, w ...

S. 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.

Similar species

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 A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

analysis shows the jack-o'-Lantern to be most closely related to the ghost fungus ''

Omphalotus nidiformis ''Omphalotus nidiformis'', or ghost fungus, is a gilled basidiomycete mushroom most notable for its bioluminescent properties. It is known to be found primarily in southern Australia and Tasmania, but was reported from India in 2012 and 2018. T ...

''. Miller notes that the colours and shades of the ghost fungus most closely resemble this species. ''

Gymnopilus junonius ''Gymnopilus junonius'' is a species of mushroom-forming fungus in the family Hymenogastraceae. Commonly known as the spectacular rustgill, this large orange mushroom is typically found growing on tree stumps, logs, or tree bases. Some subspeci ...

'' is another similar-looking species.

References

External links

* * * {{Taxonbar, from=Q7090734 Bioluminescent fungi olivascens Poisonous fungi Fungi described in 1976 Fungi of North America Fungi of Mexico Fungi without expected TNC conservation status Fungi of California