MycoNote

This English version was machine-translated from Ukrainian, so a few things may read a little off.

Science & taxonomy

Do mushrooms glow at night?

·2 min read

Some mushrooms really do glow in the dark with a soft greenish light. This phenomenon is called bioluminescence. Here's which mushrooms glow, why it happens and whether there are any in Ukraine.

Mushrooms glowing with a greenish light in the dark
Photo: Bruce McAdam · CC BY-SA 2.0 · source

Stories of a forest that glows at night aren't made up. Some mushrooms really do give off a soft greenish glow in the dark, and this phenomenon has amazed people for a long time: glowing stumps were once called "foxfire". Behind it is the same chemistry that makes fireflies glow.

Let's look at which mushrooms glow, why it happens and whether there are any in Ukraine.

What is bioluminescence

Bioluminescence is the ability of a living organism to emit light through a chemical reaction. In fungi, a substance called luciferin is oxidized with the help of an enzyme, and energy is released as light — cold light, with almost no heat. The glow is usually greenish and visible only in complete darkness.

Which mushrooms glow

About a hundred species of glowing fungi are known worldwide. The best known:

  • Honey fungus — it's not the mushroom itself that glows but the mycelium in infected wood ("foxfire").
  • Armillaria (honey fungus) in general — their mycelium in rotting stumps can glow faintly.
  • Tropical species of the genera Mycena and Omphalotus glow the brightest.

The glow probably attracts insects that spread the spores.

Are there glowing mushrooms in Ukraine

Yes, though not bright ones. Your best chance is to see the faint glow of rotting wood infected with honey fungus mycelium on a warm, damp night in complete darkness. It's not the fruiting body itself but the mycelium in a crumbling stump. There are no bright tropical glowing mushrooms in our nature.

You'll find more on honey fungus and other fun facts about mushrooms in separate articles.

Why the glow is hard to see

  • It's very faint — visible only once your eyes have adjusted to complete darkness.
  • It takes warmth and moisture — active mycelium.
  • Any outside light (a flashlight, the moon) "drowns it out".

Sources

  • “Key to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishing house).
  • Bioluminescent fungi on Wikipedia.
  • Foxfire on Wikipedia.

Frequently asked questions

Do mushrooms really glow at night?

Yes, some mushrooms give off a soft greenish light thanks to bioluminescence — the same reaction as in fireflies.

Which mushrooms glow?

About a hundred species worldwide; the brightest are tropical Mycena and Omphalotus. In our region, honey fungus mycelium glows faintly in rotting wood.

Why do mushrooms glow?

Because of a chemical reaction: a substance called luciferin is oxidized with the help of an enzyme, releasing energy as cold light. This probably attracts insects to spread the spores.

Are there glowing mushrooms in Ukraine?

Yes, but not bright ones. You can see the faint glow of a rotting stump infected with honey fungus mycelium on a warm, damp night in complete darkness.

What is "foxfire"?

It's an old name for the glow of rotting wood infected with honey fungus mycelium. What actually shines isn't fire but the fungus's mycelium.

What color is the glow of mushrooms?

Usually greenish. It's cold, with almost no heat, and very faint, so it's visible only in complete darkness.

Are glowing mushrooms dangerous?

The glow itself is harmless. But edibility depends on the species: for example, the tropical Omphalotus is poisonous, so mushrooms are always identified individually.

Why is the glow so hard to see?

It's very faint and needs complete darkness and active, moist mycelium. Any outside light drowns it out.

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