Glow-in-the-dark fungi

Omphalotus nidiformis, the Ghost Fungus, photographed by its own light

Sometimes the most unexpected things appear literally in our backyard. This happened in February 2016…

I looked out the loungeroom window and did a double take. A huge three-foot-high cluster of white fungi had sprung up on a tree stump in the backyard. Overnight, or so it seemed.

When I went outside and had a close look I noticed the caps were funnel-shaped, the centre of each brown or tinged purple; the gills underneath were forked and extended down the stem. I realised this was most likely Omphalotus nidiformis, the Ghost Fungus, famous for its bioluminescence. In other words, it glows in the dark.

The last time I saw these fungi involved a bushwalk down 1200 stairs into the Jamison Valley at night, lugging tripod and camera to photograph a small cluster in the rainforest. That was March 2013. But this colony just ten steps from my back door was the biggest I’d ever seen!

I could barely wait for night-time.

At last, when twilight dimmed into black, there it was: a ghostly glow in magnificent tiers up the sides of the stump. It took my breath away.

Glowing tiers up the sides of the stump

Omphalotus nidiformis

Slugs feed on the fungus

(Click on images to enlarge)

Omphalotus nidiformis grows on dead and living wood in forests throughout southern Australia from south-east Queensland to eastern South Australia, in Tasmania and south-west Western Australia. In case you’re wondering, it is not edible — unless you wish to spend several hours vomiting. Cases of poisoning have reputedly occurred as a result of confusion with edible oyster mushrooms.

It’s one of more than 75 species of bioluminescent fungi worldwide. Why do they glow? Bioluminescence means that light is generated by a chemical reaction inside the living organism. There are several hypotheses for its purpose in fungi. It could be that it attracts nocturnal invertebrates that help disperse the spores, or it might attract predators that eat mycetophagous (fungus-feeding) invertebrates. (While Omphalotus is poisonous to humans, this doesn’t mean it’s poisonous to other species.) Our eyes are poor at distinguishing colour in dim light so we perceive the glow as whitish. The camera, however, records it as green.

The books tell us this species has no smell, but I was aware of a powerful mushroomy odour permeating the air around the cluster. In the still night it was distinctive, evocative, and unforgettable.

Tiny rove beetles feed on spores between the gills

While taking photos over the next hour I noticed a multitude of life converging on this part of the garden. There were slugs eating the caps, tiny rove beetles feeding between the gills, moths attracted to the eerie glow and a spider on the prowl, seemingly enticed by the bonanza of bugs. The fungus had become the centre of an entire ecosystem!

The following night I realised how short-lived this ecosystem was. The fungus still glowed, though slightly less brightly but the bustle of life was gone, like a country town on a Sunday afternoon. After a few more days the cluster had shrivelled to shapeless remnants. Soon, there was no evidence at all that a wonderland of interconnected life had briefly existed on this unremarkable stump.