Panellus stipticus, commonly known as the bitter oyster, the astringent panus, the luminescent panellus, or the stiptic fungus. 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. It is a species of fungus in the Mycenaceae family, and the type species of the genus Panellus. A common and widely distributed species, it is found in Asia, Australasia, Europe, and North America, where it grows in groups or dense overlapping clusters on the logs, stumps, and trunks of deciduous trees, especially beech, oak, and birch.Panellus stipticus is one of several dozen species of fungi that are bioluminescent. Strains from eastern North America are typically bioluminescent, but those from the Pacific regions of North America and from other continents are not. The luminescence is localized to the edges of the gills and the junction of the gills with the stem and cap. 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 60 species are known. 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.