Foxfire And Bioluminescent Fungi

Aug 31, 2020

Perhaps you have heard of foxfire, an ethereal glow that appears in the deep dark woods late at night. The Masked Biologist casts some light on the subject in this week’s Wildlife Matters.

Earlier this summer I wrote a feature about fireflies. As I was researching bioluminescence, I was reminded that lightning bugs are not the only example of living organisms that emit light. Bioluminescent fungi also produce their own light, a fascinating physiological adaptation. In fact, as I started reading about bioluminescence, trying to find stories or species that apply to us here in northern Wisconsin, I was led to one of my most recent guide book acquisitions: Fascinating Fungi of the North Woods, by Cora Mullen an Larry Weber. I ordered this small affordable book and I was not disappointed; it seems like it will be a great help when I am struggling to identify a mushroom now and then. So I jotted down a few notes, telling myself I would pick the topic back up for a future episode when the seasons better align for a discussion of glowing fungus, sometimes called foxfire.

While I haven’t seen a great explanation for where the name foxfire came from, I have seen some references to possibly a twisting of the French word faux, which is spelled f-a-u-x and might be misread as fox. I can imagine that early settlers and pioneers might have been confused or alarmed when they would see it, because they would only expect light from the sky, a candle, lantern, or fire. In my mushroom guidebook, Mollen and Weber state “tales are told of folks placing pieces of wood bearing glowing mycelium of fungus to mark a path for night travel. Some claim to have read by the light.” I have to say, the glow is extremely dim, and there would either need to be a lot of mushrooms or your eyes’ night vision would have to be in peak operation. I have seen photos that show the glow, but they are usually time exposure with special equipment. The only time this light might appear bright would probably in thick woods on a moonless or cloudy night, or somewhere very dark like a cave or mine. Interestingly, the cause of foxfire was apparently discovered in 1823 because wooden support beams inside a mine seemed to glow in the dark, but upon further examination it was determined that fungus growing on the wood that was glowing.

Bioluminescent fungi seem to emit a glow in darkness to attract insects to aid in spreading spores. They don’t emit light after charging up like a glow in the dark sticker or something; there is an internal chemical reaction that emits light. The best example of a bioluminescent mushroom up here would be the jack o’ lantern, named for its greenish nighttime glow. It’s actual color is orange, which should help me remember the name, but I admit recently I saw one without remembering what it was or that I should snap a photo. I was working out in the woods and saw a big sturdy looking cup-shaped orange mushroom. It was under a thick canopy of aspen leaves, with a lot of dead wood on the ground. And of course, up until recently we had been getting regular heavy rains, great mushroom conditions. I remember thinking at first maybe it was a piece of garbage or something, so I backed up for a second look. Then I drove away. It wasn’t until days later that I realized that was probably a jack o’ lantern. From what I have seen while out and about, the best places to see fungi are in mixed deciduous forests, especially when oak trees are in the mix. A couple of articles I read seemed to agree that your best bet for seeing foxfire is to head to old, moist oak woods where you can find lots of big dead sticks, logs, and stumps. Again, a night with a new moon or thick cloud cover would probably be best. If you see the mushroom during the day like I did, you can bring it home and stare at it in your dark basement, they apparently glow for 40-50 hours after collection. Be careful not to eat it though, because it is poisonous. Another good reason to have a good guidebook and a great reason not to pick these fungi. For me, I plan to appreciate knowing they are out there, maybe I will incorporate a glow-shroom hunt with the boys while out camping on the State Forest in a few weeks, but I don’t plan on picking one to see if I can get enough light to read by.