Bioluminescence in the Bush – Glow in the Dark Mushrooms in New Zealand

Stewart Island or Rakiura in Maori means “glowing skies,” but it’s not the skies that interest me. My head is down, it’s pitch black, and I’m with a group of fungi enthusiasts, students, and mycologists on the lookout for glowing mushrooms. 

After seeing posts on Instagram and some pretty mind-blowing time-lapse videos by Australian fungi photographer Stephen Axford, witnessing glow-in-the-dark mushrooms in New Zealand was at the top of my list at the 34th annual FUNNZ fungal foray.

I took the ferry across the choppy Foveaux Strait from Bluff to Oban a day before the week-long foray was set to commence. 

I picked out a bit of grass at the Backpackers to pitch my tent and the following day hiked up the Deep Bay track towards Golden Bay and found what I was looking for: Armillaria novae-zelandiae. Also known as a honey mushroom, this wood rot fungus is one of three Armillaria species known to be bioluminescent in New Zealand. 

During the day, Armillaria species are relatively inconspicuous. They usually grow in tufts, and their caps can range in color from light to dark tan or yellow-brown. They’re sticky to touch when moist and, depending on age, can vary in shape from conical to convex to depressed in the center. The veil and collar is white, same as the spores, and small black dots speckle the apex of the cap. 

Bioluminescence: Light emitted from an organism as a result of a biochemical reaction.

The next evening is a new moon,  and a group of us make our way up the steep hill towards the Deep Bay track. No torches or white light can be used. We must allow our eyes to adjust to the darkness. Instead, red lights and dim-lit cell phone screens are used to illuminate the path before us. 

I access my memory palace and try to remember by touch where the honey mushrooms were growing. I feel a pair on a rotting log and know we’ve reached the spot. 

There are around fifteen of us laughing at the shared absurdity of a nighttime foray. The fact that such a large group is standing in the middle of the track. Not strange at all if someone were to stumble upon our coven randomly!

Opposite the track, growing on dead logs, are heaps of Armillaria novae-zelandiae that still have their veil. The younger ones glow the brightest in their stipe and unbroken veil around the cap.

We were fortunate to have both Dr. Peter Buchanan from Landcare Research and journalist and bioluminescent fungi enthusiast Anna Chinn with us. I had previously read Anna’s blog post, A Fungal Fairy-land, Revisited, and her experience witnessing bioluminescence in NZ’s forests. Her tip for us was to try and catch sight of the faint glow out of the corner of our eyes, an evolutionary trait for the human eye to detect light – Nature’s night-vision goggles.

I look down at the ground and start to see a faint white-green glow. 

Reaching down, I pick up a stick and hold it close to my face. I see insect indentations and marks that snake along the outside of the wood. The glow intensifies with time. Laughing in disbelief, the “baton” is passed around, and it reminds me of The Simpsons intro and the uranium bar that gets caught on Homer as he’s leaving the nuclear power plant. 

The glowing baton is handed to Dr. Buchanan to put in his bag to take back for analysis. The light emitted was so strong that it could be seen glowing through the bag!

Bioluminescence happens when living organisms emit light when a molecule called “luciferin” — from the Latin lucifer meaning light-bringer — combines with its enzyme partner “luciferase.” When the two mix and are exposed to atmospheric oxygen, a chemical reaction is triggered, resulting in a very “excited” oxyluciferin that releases light energy to “calm down” to its lowest energy state. 

As to why bioluminescence is present in mushrooms, there is still a lot that we don’t know. It is believed that some fungi emit light to attract insects that disperse spores and spread the fungi across the forest canopy. At the same time, what attracts insects deters mammals from consuming the mushrooms. Much like bright colors mean danger to predators, it is assumed that bioluminescence acts in much the same way.

Throughout history, this mysterious light has been manifested through literature and folklore around the world. The puzzling and disorientating will-o-the-wisp in the woods infatuates and lures people further but is something they can never reach. 

For centuries this fairy light or “Foxfire” was attributed to something mystical. The “fox” in “foxfire” is derived from the Old French word faux, meaning “false,” rather than from the name of the animal, but the association of foxes with such fires is widespread. 

For example, in Japanese folklore, Hitodama (literally “Human Soul” as a ball of energy), Hi no Tama (Ball of Flame), and others are described as balls of flame or light, at times associated with graveyards, but occurring across Japan as a whole in a wide variety of situations and locations. Kitsune, mythical yokai demons, are also associated with will ‘o the wisp, with the marriage of two kitsune producing kitsune-bi (狐火), literally meaning ‘fox-fire.’

The oldest recorded documentation of Foxfire is from 382 BC, by Aristotle, whose notes refer to a light that, unlike fire, was cold to the touch. 

And dating back to the American Revolution, Foxfire was used to illuminate the needles on the barometer and the compass of Turtle, an early submarine. Correspondence between the inventor, Benjamin Gale, and Benjamin Franklin shows that alternative forms of lighting were considered once the cold temperatures rendered the foxfire inactive. 

Early scientists and naturalists reference foxfire, but the cause was discovered in 1823 when wooden support beams emitted a glow in a mine shaft. It was found to be bioluminescence from fungal growth. The light results from a chemical reaction made while the fungus breaks down and consumes the wood.

We pass a massive glowing fern frond overhead. I pick a few honey mushrooms and hold them close to my face and see the stipes and veils glowing. Once our eyes adjust, more and more mycelium and mushrooms become visible.

Night after night, we would go out to where honey mushrooms were growing. Near the Fuchsia Track next to the Rugby field where people go at night to look for Kiwi, I pick a handful of Armillaria and place them in a vantablack-felt-like cloth, and the glow is maximized. 

Now holding a cold lantern, I make my way down to a bridge where others view Mycena roseoflava, which dot a tree branch, appearing like stars in the night sky. This was an exciting find during the foray, as M. roseoflava was something new to observe glowing. 

David Hera, a Ph.D. student and photographer living in Christchurch, and I spent hours out in the dark with tripods attempting to capture the magic. Some of David’s shots can be viewed here.

A group of nighttime hikers looking for Kiwi can be heard up the track, and flashes of red and white lamp light encroach on our scene. We explain to them what we’re doing and show them some of the results on our cameras. A niche hobby, you could say. We can hear them talking with each other as they walk off, “I’ve never encountered a nighttime fungi photographer!” “I didn’t know that was a thing!” We laugh, and I think “nighttime bioluminescent fungi photography” sounds good on a resume.

Little is known about glow-in-the-dark mushrooms in New Zealand. Deforestation and light pollution caused by more urban development makes it even trickier to witness. Only ~100 out of around 100,000 fungal species are known to be bioluminescent around the world. Yet the nighttime bush still holds the allure and excitement of discovering undocumented bioluminescent species of fungi.

UPDATE (22/07/2021):

Fungi enthusiast and friend Cath Smith mentioned she had spotted a Mycena vinacea. This species was reported to glow in Malaysia. Knowing this, I was excited to test if the species here would glow as well. And indeed, it did! This is the first record of Mycena vinacea glowing in New Zealand. Interestingly the species grows in soil amongst leaf litter and only glows in the basidiomes (where spores are produced in the gills). The photos below show the faint glow, so if viewing on a mobile device it’s best if the brightness is turned all the way up.

References:

Chew, Audrey L.C., et al. “Four New Bioluminescent Taxa of MYCENA SECT. Calodontes from Peninsular Malaysia.” Mycologia, vol. 106, no. 5, 2014, pp. 976–988., doi:10.3852/13-274.

Chinn, Anna. A Fungal Fairy-Land, Revisited, International Dark-Sky Association , 15 Apr. 2019, www.darksky.org/a-fungal-fairy-land-revisited/.