Last updated May 31, 2018 at 1:05 pm
It’s the perfect time of year to go hunting for ghost mushrooms.
Close your eyes and let them adjust to the darkness, instructs our guide. It’s 6.30pm and I’ve driven 500km to a pine forest outside Mt Gambier to visit Ghost Mushroom Lane, one of the largest concentrations of the Australian native glow-in-the-dark Ghost Mushroom.
The tour is organised by Forestry SA, which manages the pine plantation. A group of around 20 of us have been brought a few hundred metres into the forest to a particularly good patch of our target – Omphalotus nidiformis. Its latin name means naval nest shape, and in the torchlight they’re a creamy white colour with a dark patch on top, fanned out in clumps all over the stumps of pines.
The guide asks us all to go dark, and we dutifully switch off our torches. Our eyes adjust to the darkness, and there are delighted, hushed gasps as the gentle glow of the mushrooms becomes visible.
Photos of the ghost mushrooms show as a glow-in-the-dark green, but to my naked eye they appear more like a soft white light.
They glow from the gills, so it’s easier to detect the glow from side on in the more distant mushrooms than the ones you’re standing right on top of.
Turning around I can see dozens of glowing clumps scattered through the forest floor.
“The first time I saw them my jaw dropped, and I think that’s the sort of reaction we’re looking for” says Troy Horn, Conservation planner for Forestry SA. This year is the first that they’ve run guided tours to the area.
The birth of Ghost Mushroom Lane
Ghost Mushroom Lane was only christened in 2017. You can’t find it on Google yet, but when we arrive it’s well signposted, there’s an information display and even an on-theme green light spilling out from a coffee caravan getting in on the action.
“We’re pretty excited. We weren’t expecting it to take off as quickly as it did,” said Troy.
Over 18,500 people visited in 2017, and it’s only growing in 2018. The site was popularised after a local photographer, Ockert Le Roux, captured them in a series of stunning images.
Ockert had been reading up about the species and set out to see if he could find it in his local area.
“I remember it was a Thursday morning and I set out on a random trip in my car heading out towards the west of Mt Gambier, and I ended up in forest of Kangaroo Flat Road,” says Ockert.
He eventually stumbled on to a colony of mushrooms that matched the description he’d read of the ghost mushroom.
“I went back to the same spot the next day after the moon had set, got out of the car and as I walked out it was like a fairy city, I was blown away by what I saw,” says Ockert.
“In New South Wales or Tasmania you need to cover quite a distance to find them. This site is unique because they’re in such high density. When you go to that site you will 100% see them this time of year.”
Ockert posted the pictures he captured in May 2016 to social media, and the interest skyrocketed. He’s even produced a handy photography guide to help you get the best shot. (Trust me, your iPhone is no good for getting that glow.)
I ask if he’s concerned that the spike in popularity might start causing environmental problems.
“With the trails, it’s a decaying forest environment and every 10 years or so they stick harvesting machines through so it’s a very changing environment anyway,” says Troy.
“I’m pleasantly surprised with how well people are treating the area. You might get the occasional thing where someone has kicked a mushroom but people are being careful and taking their rubbish with them.”
If anything, he points out, having people walking through the area might actually help the mushroom spores spread further through the forest.
Where to find them
The ghost mushroom isn’t exactly rare. The first written description of them in Australia was by James Drummond in 1842 who had found it growing on “the stump of a banksia tree near the jetty at Perth”.
Writing about them in 1967, botanist James Hamlyn Willis described their odour as “pleasant and bread like”, and that the glow given off by the mushrooms was enough to read a newspaper by.
The ATLAS of Living Australia records sightings showing they’ve been spotted as far north as Queensland, down to the tip of Tasmania and right across the southern part of the mainland.
The Ghost Mushroom Lane plantation seems to provide the perfect mix of rotting wood, wet and cold conditions for them to thrive.
“They’ve adapted to the pine stumps,” says Troy. “They are a native Australian species and we do see them in native forests but not at the densities that we see in the plantation forests.”
The actual fruiting bodies, the mushrooms, come out for around an eight-week season from May to June.
So why the glow?
“It’s a good question, but we really don’t know, is the the short answer,” says Troy.
The glow is caused by a chemical reaction involving the enzyme luciferase, similar to what happens in glow worms or fireflies.
One hypothesis is that the glow might attract bugs to help spread the spores, and during the tour I see a millipede crawling across the glowing surface. The tour guide tells us they’ve seen slugs eating them. A spider is camped out in the middle of one, but scientists don’t think the glow has anything to do with attracting insects.
“In the tropics there are fungi that glow to attract insects that act to disperse their spores,” says Philip Weinstein from the University of Adelaide. He thinks that this might be the reason that the ghost mushrooms were lighting up, and so carried out some experiments on Kangaroo Island in 2016 to test that hypothesis.
“The experiment we did showed the mushrooms that glow don’t attract any more insects than control,” says Philip. “There are strains that don’t glow, so if there were an advantage you’d think they would all glow, otherwise the ones that don’t would go extinct.”
Other bioluminescent creatures use glowing as a warning signal to predators that they are toxic. But, while ghost mushrooms are poisonous to humans, they don’t seem to harm the slugs or millipedes that happily munch on them.
Troy Horn says that his group’s current theory is that the glowing might show a circadian rhythm. That appears to be confirmed by Ockert Le Roux, who has failed to see the mushrooms glowing during daylight hours, even when put into a dark cupboard.
“The jury is still out on that one,” says Ockert. He was part of a group that brought a few specimens in from the forest to make a static display in Mt Gambier for people who find it too difficult to nagivate the forest at night. Informally, they’ve noted that light intensity is not equal throughout the night, with the glow intensity peaking around the time of sporing.
So while the mystery of why they glow is yet to be solved, Philip Weinstein says that it may just be that there is no biological purpose for the glow.
“It’s most likely to just be an accidental by-product of their metabolism,” he says.
If you have the chance to go out and experience this wonderful accident of nature, I recommend it.
With thanks to Ockert Le Roux for the images used in this article.
If you love fungi, be sure to check out our SCINEMA International Science Film Festival screenings happening around the country from 31 May – 21 June, featuring The Kingdom – how fungi made our world as winner of the Best Film for 2018.