A glow-in-the-dark mushroom not seen since 1840 has been rediscovered in a Brazilian rain forest and reclassified. The bioluminescent fungus was discovered by San Francisco State University researcher Dennis Desjardin and his team in 2009. They have now collected new specimens of the forgotten mushroom, which was named Agaricus gardneri, and reclassified it as Neonothopanus gardneri. Their findings were published online June 23 in Mycologia (doi: 10.3852/11-097). Neonothopanus gardneri was last seen in 1840 when George Gardner, a British botanist, spotted boys playing with a glowing object they called “flor de coco.” Neonothopanus gardneri. Images courtesy of Cassius V. Stevani, IQ-USP, Brazil. To catch the green glow of the bioluminescent fungi, Desjardin and his longtime Brazilian research partner, Dr. Cassius Stevani, stumbled around the forest on new moon nights searching for the ghostly glow. Digital cameras allowed them to photograph mushrooms they suspected might be bioluminescent in darkened rooms. They then analyzed the photos for a glow – sometimes invisible to the human eye – within a few minutes, rather than the 30 to 40 minutes required of regular film exposure. Capturing the imaginations of cultures around the world, bioluminescent fungi have existed for centuries, from the bright orange and poisonous jack-o’-lantern mushrooms to the phenomenon called “foxfire,” where the nutrient-sipping threads of the honey mushroom give off a faint, eerie glow in rotten logs. But the scientists wanted to know how a fungus glows, and why. Although they believe that fungi make light in the same way fireflies do – through a chemical mix of a luciferin compound and a luciferase – they have not been able to identify either of those in fungi. As long as water and oxygen are available, Desjardin said, the fungi glow 24 hours a day, unlike bioluminescent animals who produce light only in spurts. “This tells us that the chemical that is acted upon by the enzyme in mushrooms has to be readily available and abundant,” he said. The “why” behind the glow also remains a mystery. Some scientists think that mushrooms with spore-bearing glowing parts might attract insects that can help disperse the spores to grow new mushrooms. However, in the case of the foxfire, the threadlike mycelium, which seeks out nutrients for the fungi, is what glows. Insects drawn to the mycelium might do more harm than good to the fungi if they ate the attractively lit structures.