What Makes a Mushroom Glow
The glow comes from a chemical reaction inside the fungus, not from any external light source. A compound called luciferin reacts with oxygen, aided by an enzyme called luciferase, and the reaction releases energy in the form of light instead of heat. This is the same basic principle that makes fireflies glow, though the exact chemicals involved are different between fungi and insects.
In mushrooms, scientists have traced the glow to a compound related to hispidin, which gets converted into a fungal luciferin through a multi-step chemical pathway. Researchers only fully mapped this pathway in the 2010s, which is relatively recent given how long people have known about glowing fungi.
The light itself is usually a soft green, and it's often too dim to notice in daylight or even under a flashlight beam. Your eyes need to fully adjust to darkness, sometimes for 20 to 30 minutes, before the glow becomes visible.
Which Mushrooms Actually Glow
Not all mushrooms glow, and the ones that do aren't always glowing the same way. Some notable examples:
• Mycena chlorophos – Found in subtropical regions like Japan and Brazil, this small, delicate mushroom produces one of the brightest glows of any fungus.
• Panellus stipticus – A tiny shelf-like mushroom found in North America and parts of Asia, known for glowing mycelium (the thread-like network fungi grow from) as much as the mushroom cap itself.
• Armillaria species, commonly called honey fungus – Responsible for much of what's historically been called "foxfire," a glow seen in decaying wood infected by the fungus's underground network.
• Omphalotus species, or jack-o'-lantern mushrooms – Bright orange in daylight, these gills glow faintly at night and are often mistaken for edible chanterelles, despite being toxic.
Interestingly, in many species it's not just the mushroom that glows. The mycelium and even the wood the fungus has colonized can emit light too.
Why Would a Mushroom Bother Glowing?
This is where things get more interesting. Producing light costs the organism energy, so there's likely an evolutionary reason for it.
The leading theory, supported by field studies on Neonothopanus gardneri in Brazilian forests, is that the glow attracts insects at night. Insects that land on or near the glowing mushroom pick up spores and carry them elsewhere, helping the fungus spread in dense forest environments where wind alone isn't very effective at dispersing spores. Researchers tested this by building artificial glowing mushroom replicas and found they attracted insects at similar rates to the real thing, while non-glowing replicas didn't.
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That said, not every glowing fungus needs insects for spore dispersal, so scientists think there may be more than one explanation depending on the species, and some of the glowing might simply be a biochemical byproduct without a strong evolutionary purpose of its own.
A Phenomenon Known Since Ancient Times
Glowing wood and fungi aren't a new discovery. Aristotle wrote about a cold light coming from decaying wood over two thousand years ago, and sailors for centuries reported eerie glows in ship holds caused by fungus-infected timber. It wasn't until modern chemistry that anyone understood what was actually happening at a molecular level.
Where and When to See It
If you want a chance at spotting bioluminescent fungi yourself, timing and location matter. Warm, humid forests after rain tend to be best, since that's when fungi are most active. You'll need genuinely dark conditions, away from artificial light, and patience for your eyes to adjust. Even then, the glow is subtle rather than dramatic, more like a faint green shimmer than a lit-up mushroom from a fantasy movie.
It's a quiet reminder that some of nature's strangest tricks are happening constantly, just below the threshold of what we usually notice.
