BREATH easy, the eerily green glow appearing in central Victoria is a mushroom, not a poltergeist.
This otherworldly "ghost fungus" will not harm you - unless you eat it.
If you do, you may liken what comes next to a scene out of the classic horror movie The Exorcist.
The vomit will not be nearly as spectacularly as the demon that possesses 12-year-old movie character Regan, but it will come out of your mouth.
Alison Pouliot hears at least one new story about someone eating them every year.
They have usually mistaken the fungi for oyster mushrooms and do not realise their harvest glows in the dark, she says.
"Ghost fungi grow in great abundance so people think 'wow, what a fantastic feast growing on the side of this tree'," Dr Pouliot says.
"They cook them up and very quickly, often within half-an-hour, they are ejecting them from their bodies - rather violently."
The fungi kingdom produces a dizzying array of complex toxins.
"There's ones that give you basic gastrointestinal food poisoning, then there's ones that dismantle your liver, dismantle your kidneys, some that send you on a trip and others that cause your skin to come off," Dr Pouliot says.
The good news is that a ghost fungi is unlikely to kill you.
"But it is certainly one of those ones that will make you feel like you are going to die," Dr Pouliot says.
Ghost fungi should start appearing across the region right about now.
"I haven't spotted one yet but I reckon I will find some in the coming days," Dr Pouliot says.
The fungus is often found on pine stumps but can be seen on other tree species including eucalyptus varieties.
It prefers deadwood.
No-one is sure why the ghost fungus glows.
Scientists have had a few theories over the years.
Some have thought it could be to attract insects. They have reasoned that other creatures use insects to spread the "spores" that fungi use like plants do seeds.
"For example, native mammals spread Australian truffles by digging them up, bouncing off and distributing the spores," Dr Pouliot says.
"Some spores need to be eaten so that their casings are broken down by enzymes in an animal's digestive tract."
Scientists' tests appear to have ruled out a link between insects and ghost fungi.
"They counted the number of insects on glowing fungi and those which didn't glow and it was exactly the same," Dr Pouliot says.
It could be that ghost fungi develop toxins to repel plants or animals so that they can mature and release their spores.
"Maybe it's just some kind of secondary byproduct of a chemical reaction," Dr Pouliot says.
Or maybe it boils down to some idea scientists are yet to think of.
"I always reckon it's to help the wombats find their way through the forest at night," Dr Pouliot jokes.
Scientists simply do not know enough about ghost fungi to say what is going on.
"We are not paying people to do this research. Trying to get a PhD in fungi is almost impossible," Dr Pouliot says.
"There are all these projects waiting to be done if we are to understand why these fungi glow green."
Part of the problem is that scientists have long focused greater attention on plants and animals.
They have also muddled things up.
In one case, a botanist in England mistook an Australian native species for separate European species.
The European variety is safe to eat and highly sought-after in the northern hemisphere
Luckily for the botanist and colonial diners, the Australian species turned out to be safe to eat.
Scientists only fully appreciated the scale of the mistake centuries later when they started looking at the fungus at a molecular level.
"It is not just morels, it's all our native fungi. They were being named in the 19th century when people sent specimens to the Kew Gardens in England," Dr Pouliot says.
"So some poor mycologist was being sent withered specimens, which took three months to arrive, and holding them up next to theirs for comparison."
Dr Pouliot has found native morels around Big Hill in low nutrient, granite soils.
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They usually appear above the ground in spring, so it is not worth going out and looking for them this time of year.
Many mushroom varieties pop through the earth's surface in autumn and winter, when conditions are just right for most species.
Dr Pouliot is expecting an unusually cool summer and plenty of rain will create perfect conditions for them this autumn.
She and co-author Tom May have just published a new book for Australian foragers hoping to safely look for edible fungi.
Wild Mushrooming: A Guide for Foragers has been published by Australia's peak science agency the CSIRO.
The authors spent five years scouring the internet for claims that mushrooms are edible, then seeing what science could confirm.
"In Australia we have what we call 'emerging species', and by that I mean species where someone has said that they have eaten it," Dr Pouliot says.
"But we can't assume it really is edible just because one person tells us that. That person often won't have the specimen, we can't be sure what they said it true or be 100 per cent sure what they ate actually was what they thought it was."
She is appearing at a series of public events in central Victoria over the next few months, including in Lockwood on Tuesday and Bendigo in early April.
For more information about those events or her books, click here.
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