While glowing mushrooms are typically associated with tropical rainforests, a remarkable discovery in Switzerland is shifting that narrative. Zurich-based artists Heidy Baggenstos and Andreas Rudolf—who have spent over a decade exploring bioluminescent organisms—have identified a new glowing fungus in their own backyard.
“We want to show that bioluminescent mushrooms are part of Swiss forest biodiversity—you don’t need to travel far to find them,” says Baggenstos. One evening during a walk in the Albisrieden forest near Zurich, the duo noticed a faint green glow through their camera lens. Since fungal bioluminescence is often too dim to detect with the naked eye, such sightings require complete darkness. “In today’s world, we’re always using phones or flashlights—but to witness true forest bioluminescence, you need pitch black surroundings,” adds Rudolf.
Initially believing the glowing specimen to be Mycena haematopus, a known luminescent species, they brought it to their studio. To their surprise, it turned out to be Mycena crocata—commonly known as the saffron drop bonnet—previously unreported as bioluminescent.
Bridging Art and Science
Collaborating with Renate Heinzelmann, a mycologist at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), the artists conducted detailed analyses. Their findings, now published in Mycoscience, involved using long-exposure photography and a luminometer to measure light emission. “The artists did most of the experimental work—collecting specimens, capturing images, and quantifying the light,” Heinzelmann notes.
Bioluminescence, the result of a chemical reaction where luciferin is oxidized by luciferase to emit light, does not require an external light source—unlike fluorescence. In M. crocata, the mycelium—the underground fungal network—displayed the most intense glow, while the mushroom cap and stalk remained mostly non-luminous. When this mycelium-infused decaying wood is split, it can glow green for up to four hours until it dries out. In optimal lab conditions, the artists were able to culture glowing mycelium that retained its luminescence for an astounding 164 days.
Shedding Light on Fungal Mysteries
Heinzelmann’s genetic analysis confirmed both the identity of M. crocata and the presence of luminescence-associated genes shared by all glowing Mycena species. “Bioluminescence is still underexplored. As more people search for it, we’re likely to discover many more luminous fungi,” she explains.
Although humans have marveled at bioluminescent fungi since the time of Aristotle—who called it a “cold fire” emerging from rotting wood—its ecological purpose remains uncertain. While it’s speculated that the glow may help spread spores by attracting insects, this doesn’t explain the luminescence in underground mycelium.
“The trait seems to have been conserved over millions of years,” Heinzelmann reflects, “so it must serve a purpose—but what that is, remains a mystery.”
