I had worked overtime for 3 weeks in a row.  I needed a break.  I was determined to go to the woods for as long as possible.  I managed to carve out one full day, two nights, and two half days.  I took no camera, no journal, no book.  I just needed to unwind, to take in some natural beauty, to feel no obligation – not even the obligation to blog about it…  After all, I’ve been in the gorge a million times in every season of the year.  It was unlikely I would see anything I haven’t seen before, right?


It rained Saturday afternoon.  Perhaps that helped provide the perfect conditions for Saturday night.  I half-woke when an adjustment of the sleeping bag was required.  Through half-opened eyes, I noticed the forest floor was dappled with light.  My half-alert mind turned my eyes to the sky to search out the moon, which I figured must be the source.


The moon was obscured by clouds.  Logs, stumps, and even clumps of leaves were glowing.  All by themselves.  All around me.  Even under me – shining through the translucent ground cloth.   I had heard about glow-in-the-dark fungi, but this was my first time seeing it!

Now, remember, I had no camera… so I borrowed this photo from Flickr:

glowing fungus

Photo by Luke T. on Flickr

Searching around the internet, I found a website from the University of Georgia (link below) that said this:

Armillaria mellea and a closely related relative are common root rot and wood decay fungi found across North America, Europe and Asia. Armillaria grows in (and on) old stumps, dead trees, buried roots, and downed logs. The fruiting body of Armillaria is a small golden-colored, stalked mushroom. This fruiting body is not luminescent. Armillaria’s mycelium and rhizomorphs are luminous. The root-like dark rhizomorphs, when they stop growing or when entering a resting period loose luminosity.

Rhizomorphs of Armillaria mellea

Rhizomorphs of Armillaria mellea

Now that name – Amillaria mellea – that sounded familiar to me.  I searched MY OWN pictures and blog and found, sure enough, I had encountered it before.  Somehow, it never came out in my previous research that parts of this fungus are bio-luminescent under the right conditions.  The University of Georgia website lists the following ideal conditions for observing this phenomenon sometimes called foxfire or more fancifully faery fire:

Food — The cell wall components and remains of sugars, starch, and proteins in the wood are the desired food-stock of Armillaria. The luminescence can last in one piece of wood for up to 8 weeks until essential resources are consumed. It usually takes at least 4 weeks to build to maximum luminescence.

H2O — The rotting wood must be kept moist — too dry and the fungal growth stops — too wet and the fungal growth is suffocated. Moisture is an important feature of luminescent wood because the process of light generation produces water as a by-product. Luminescent wood feels saturated. If you are collecting luminescent wood, the glowing, rotting pieces of wood need to be kept moist, not soaked. Do not let the wood become dry even for a short time.

O2 — Oxygen is critical to keep the fungi healthy and growing. Too much water can make oxygen movement more difficult, and light generation will decline and be extinguished. With small pieces of collected luminescent wood, try limiting oxygen and watch as the light fades. You can then quickly let oxygen back to the wood and, under the right conditions, you will be rewarded with a “flash” of light. Do this in complete darkness.

Temperature – The optimum temperature for Armillaria bioluminescence is 77°F (25°C). Light generation is noticeable as low as 34°F (1°C). Light generation declines rapidly and stops above 86°F (30°C)

I also really liked this simple explanation:

One way to understand bioluminescence is by comparison with photosynthesis. Bioluminescence is the reverse of photosynthesis. In photosynthesis, a living organism captures light and carbon-dioxide (CO2) to make organic materials and release oxygen. In bioluminescence, light and carbon-dioxide (CO2) are released by breaking apart organic materials using oxygen.

The whole article is great.  Click the link below to go read it!

Learn More:

12 thoughts on “Foxfire

  1. How fantastic to be there at the optimum moment. I often find that things I can’t photograph for lack of a camera become even better words than they would have photos.

  2. i have seen bioluminescence in the bays (and once on incoming waves of a beach) of my native puerto rico, but never in the us, though i have read about it. how truly amazing! you will keep the memory alive simply because the emotion upon seeing this phenomenon was so intense!

  3. Fantastic. Very inspiring to see a teacher who’s so passionate about her subject.
    I’m a young biologist hoping to go into teaching (and new to blogging too) so it’s nice to see someone successful in a similar field

    • Apparently, not. My favorite mushroom blog says this about Armillaria mellea:

      The classic honey mushroom, Armillaria mellea, turns out to be limited to roughly the eastern half of North America, from about the Great Lakes to the Gulf Coast and the East Coast–and perhaps to northern California, where it has been reported. It usually grows in clusters on hardwoods, but is occasionally found on conifers.

      The woods where I found it had a lot of maple, beech, and hemlock.

  4. I was camping at Tettegouche State park in Northern Minnesota this week. My nephews spent the day hacking on a rotting log with a hatchet and spread the pieces around the camsite. When going to bed, I noticed much of the campsite glowing. it was like looking at the night sky! This woods was mainly birch and some conifers.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s