Out of about 14,000 described species of mushrooms, there are at least 65 species of glowing mushrooms. To produce light, also called bioluminescence, a pigment, known generically as luciferin, is oxidized in the presence of an enzyme, luciferase, to produce oxyluciferin and light. Glowing mushrooms can be found in at least 16 different lineages of mushrooms. Rather than each lineage having evolving bioluminesence independently, it is thought that all of them derive from a bioluminescent common ancestor, and numerous species simply lost the ability to produce light.
Glowing mushrooms produce light 24 hours a day, though they are only clearly visible at night. These mushrooms produce light for different reasons -- some, to attract animals to disperse spores, others, to attract predators of insects that feed on them. Some of these mushrooms include the Honey Mushroom (Armillaria mellea), Jack O' Lantern Mushroom, Mellenea chlorophora, Mycena citricolor, Luminescent Panellus, and others. They are most numerous in the tropics, but can be found in temperate regions as well. One forest in southern Brazil harbors nine species, the most in any one place.
Historically, the appearance of glow-in-the-dark mushrooms in a forest at night has been called foxfire. Accounts of it can be found in ancient Greek, Roman, and Indian texts. Glowing mushrooms usually feed on the lignin in trees, and their mycellium (feeding hairs) are bioluminescent as well, giving fallen trees the appearance of being wrapped in a glowing blanket. Much mythology surrounds foxfire. Glowing mushrooms have also been used widely as sources of light prior to electricity. They have been used for light to dig tunnels, as well as being employed in the first submarine used in battle, the Turtle, on the advice of Ben Franklin.
In modern times, glow-in-the-dark mushrooms are sometimes associated with drug culture. This probably isn't because drug users keep these mushrooms more often than anyone else, but because one popular hallucinogenic drug are psilocybin mushrooms, making mushrooms a popular motif. Glowing mushrooms therefore appear on black-light posters which are used to entertain people who are high.