The public is once again needed to help document a rare and unique-looking fungus called sarcosoma globosum — more commonly known as witches cauldron — that’s been seen around Prince George.
Michael Preston, an assistant professor with the ecosystem science and management program at the University of Northern British Columbia (UNBC) has been studying the fungus since it was spotted in the region last year.
He’s in the process of officially documenting its existence in the region as the fungus, which is normally found in northern Europe, is so rare and unique that it has not been formally identified in B.C.
Preston created a survey asking the public to send him photographs and GPS coordinates if they spotted witches cauldron so he could document it and include it in his research.
He said he thought the survey would garner maybe three or four responses, but has received hundreds since it was launched last year.
"That is really encouraging that people are interested in mycology and it was the most heartwarming thing that I could ever imagine,” said Preston. "But everybody gets excited about it. You know, it’s a weird-looking mushroom, and we don’t know what it does, and it has a really cool name."
Very little is known about this rare fungus and Preston is trying to answer some big questions regarding its presence in the region – does it appear in the same places every year and what exactly is its ecological role?
“It’s really encouraging they are coming back when conditions are right,” said Preston, noting that he’s already started receiving new reports of witches cauldron popping up near Prince George.
“What I am trying to do is get data again this year that we can add to our study that we have already compiled, and then we will publish that in the scientific literature in the coming months.”
What we’ve learned about the mysterious fungus so far
Preston said since he began his research, he’s received reports of witches cauldron as far north as Highland River Provincial Park which is near the Yukon border, as far west as Houston, as far south as Quesnel and as far east as Jasper National Park.
“In a rough estimate that is a 700 km square area where sarcosoma is – so that is a significant increase in its global distribution.”
Of all the responses he’s received only one sighting was found in a provincially protected area the rest were found on private land or designated cutblocks, which Preston says is notable because the number one cause of concern for witches cauldron is loss of habitat.
However, in two instances witches cauldron was spotted in forests that had been previously logged in the 1950s, which is a significant finding because the small amount of research that exists indicated witches cauldron was only found in old growth forests.
“That shows that is probably not the case and that is somewhat of a good new story and corroborates a little bit of evidence that came out of Europe.”
Preston said there is also some debate as to whether the fungus decomposes dead organic matter (saprotrophic) or if it has a symbiotic relationship with trees (mycorrhizal) and some of his findings have begun to answer that question.
“We don’t know, and we still don’t have experimental evidence but we have observational evidence that somebody found a line of witches cauldron growing on a rotting log so that is indicating it is more of a saprotrophic,” said Preston. “That is leaning towards that way but doesn’t confirm it.”
Preston is also trying to conduct DNA analysis on the witches cauldron, but he needs to collect fresh mushrooms that still have spores.
He wants to analyze the DNA to confirm it’s the same species that’s been found in eastern Canada, Scandinavia as well as Russia.
“If the DNA analysis works and we can do full genome sequencing that will ell me what that organism is capable of but that is tricky,” said Preston.
“Identifying it is step one and step two is to do proper experimental work and that is part of the research.”
What we still need to know about witches cauldron
Preston said witches cauldron has been linked to climate change but because it's so rare it’s hard to relate its appearance to climate trends.
“What I would be interested to know is the potential implications of extreme climate events that B.C. has been facing. Last year we had the heat dome, followed by extreme forest fires, followed by atmospheric rivers so what is that doing to the mushroom?” asked Preston.
“By focusing on these species, it could be implications of what is going to happen the wider fungal community and ultimately forest health because they are so important in recycling those nutrients.”
Preston said it’s estimated there are 10,000 fungi species in B.C. and only a few have been identified and witches cauldron is just the tip of the iceberg.
“That is the exciting bit. Getting people out in the forests looking for these mushrooms, finding other mushrooms while they are doing it, and understanding the role that fungi and microbes, in general, have in a healthy forest.”
Preston has again created a survey for the public to fill out if they spot witches' cauldron when they are out exploring.
All you have to do is take a photo — or selfie — of the witches cauldron and note the GPS location (which you can do through an app) and submit that info through this online survey which goes directly to Preston at UNBC.
He added it’s also helpful to include additional details about the environment like what kind of forest did you find it in and what are the conditions of the forest floor.
“You can expect to see it until the end of May but now is the time,” said Preston, adding the fruiting body lasts for about a week before it starts degrading.
“If you want to see fresh-looking ones now is the time and now is the time to let me know where it is so I can go and collect some."