deer are also known to consume the fungus. Mating studies Panellus stipticus uses a heterothallic, tetrapolar mating system: each basidiospore develops into a self-sterile mycelium which, when grown alone, remains homokaryotic (i.e., with all cells genetically identical) indefinitely. Researchers have paired collections of P. stipticus from Japan and Eastern North America, and later, collections from New Zealand and Russia. Although the separated allopatric populations differ in bioluminescence and taste, the results revealed a universal intercompatibility group over these geographical regions. In a 2001 study, Jin and colleagues also paired geographically representative collections of the fungus, but observed a reduced ability to cross between Northern Hemisphere and Oceanian collections, as well as between and within Oceanian collections. Bioluminescence Bioluminescence refers to the ability of certain living things in the environment to produce light by the action of enzymes. Bioluminescent fungi are widespread, and over 70 species are known (List of bioluminescent fungus species). Although the intensity of their luminescence is generally low compared to many other bioluminescent organisms, fungi glow continuously for days, so their total emission is comparable with that of most brightly luminescent organisms, such as fireflies. Luminous fungi are found growing on decaying wood, leading to the popular name of "foxfire" or "glow wood" when their glow is visible at night. The responsible oxidative enzymes—known generically as luciferases—produce light by oxidizing a pigment called a luciferin. In some areas, P. stypticus is bioluminescent, and the fruit bodies of these strains will glow in the dark when fresh or sometimes when revived in water after drying. An early record of luminescence noted in P. stypticus was made by the American naturalist Thomas G. Gentry in 1885. Job Bicknell Ellis, reporting on the phenomenon for the Journal of Mycology, wrote: By careful examination, the luminosity was found to proceed from the gills and not the stipe, nor from any fragment of rotten wood attached to the specimen. This phosphorescence was not observed in all specimens brought in for examination, and seemed to depend on some peculiar condition of the air, having been noticed only in specimens gathered in damp weather or just before a storm. Canadian mycologist Buller in 1924 described the gills of P. stipticus in North America as luminescent, and noted that the fungus glows most strongly at the time of spore maturation. Bioluminescence has not been observed in European specimens, in Pacific North American collections, nor in