The death cap mushroom, Amanita phalloides, is a deadly fungus commonly mistaken for edible mushrooms.
The poisonous fungus is usually found during autumn but wet weather has prompted its early arrival in 2015. So what do we know about this little fungus?
How dangerous is the death cap?
Ingesting one death cap mushroom is enough to kill a healthy adult.
All parts of the mushroom are poisonous; cooking or peeling does not make the mushroom safe to eat.
There is no way to remove the poison from the mushroom.
The poisonous compounds are extremely stable. You cannot remove them by soaking, cooking or drying.
The poisons are found throughout the cap, gills, stem and spores.
What does it look like?
The caps of the mushrooms are 40-160mm wide, usually pale green to yellow in colour, with distinctive white gills and white stem.
It has a membranous skirt on the upper part of the stem and a cup-like structure around the base of the stem (called a volva).
Sometimes the bulbous base and the volva are partially buried in the soil or hidden by grass and leaf litter.
The cap may be slippery and sticky to touch and shiny when dry.
Variations can see the cap an olive to light brown colour.
"It also always has a slight ammonia-like smell, sometimes quite pronounced like household ammonia," said fungi expert Heino Lepp.
Mr Lepp, who is an honorary scientific associate at the Australian National Botanic Gardens, said the death cap was easily identifiable to those experienced in identifying mushrooms.
But he said it was better to err on the side of caution and avoid picking wild mushrooms during autumn.
He said there were far more "unknowns than knowns" when it comes to native Australian mushrooms.
"In Canberra because we have a mix of native vegetation as well as exotic vegetation, a lot of mushrooms grow in association with trees," he said.
"There are a lot of unknown species of Australian mushrooms. Australia has quite a number of native amanita species which grow in symbiotic association with gum trees of which nothing is known about the toxicity.
"It would be surprising if there weren't native species that were poisonous."
Where is it found?
Death caps are common in many Canberra suburbs and can be found growing near established oak trees during warm, wet autumn weather.
It is also well-established in several Melbourne suburbs and in some Victorian country towns near Melbourne.
It is not native to Australia and was accidentally introduced from the northern hemisphere.
Death cap v straw mushroom
The straw mushroom (Volvariella volvacea) is grown and eaten throughout Asia but it does not grow naturally in Australia.
However the species Volvariella speciosa is found naturally in many parts of Australia and looks very similar to the straw mushroom.
Each species of Volvariella has a volva at the base of the stem and the gills do not reach the stem - just like the death cap.
But with Volvariella there is no ring on the stem and the gills are pale pinkish-brown, rather than white.
The cap is also more brown to greyish and more-or-less conical.
However you could easily overlook some of these differences in a hasty examination and much depends on the weather.
Mr Lepp said some Asian migrants or new Canberra residents pick death caps accidentally.
"If you've grown up with straw mushrooms and think you recognise them, you might go and pick one of these and think you know what it is," he said.
What are the symptoms of death cap poisoning?
Symptoms of poisoning generally appear between six and 24 hours after ingesting the death cap and can begin with nausea, vomiting and diarrhoea.
Those who fall ill can improve after a day or two, giving a false impression of recovery. But by that stage the toxin can have caused serious liver damage which can be fatal.
Death cap poisoning is considered a medical emergency. If you suspect you have eaten some go to hospital immediately. If possible, take a sample of the mushroom with you.
If you need more information or assistance regarding a suspected poisoning call the Poisons Information Centre on 13 11 26 (24 hours a day, seven days a week).