As Manitobans head outdoors to pick mushrooms this fall, a fungi expert at the University of Manitoba is warning people to be careful, as a close relative of the poisonous mushroom that killed a three-year-old boy in B.C. last week grows in Manitoba.

Biology and mycology professor Tom Booth said he was "horrified" to hear a boy died after foraging for wild mushrooms with his family in downtown Victoria.

"It is possible to avoid such a situation," said Booth.

The mushroom that killed the boy was a highly poisonous Amanita phalloides, commonly known as a death cap mushroom. A close relative of the Amanita phalloides is the Amanita virosa, known as the destroying angel.

Amanita virosa grows across western North America, including here in Manitoba.

The two mushrooms, destroying angels and death caps, look remarkably similar — small white or cream-coloured mushrooms that resemble button mushrooms available at grocery stores. In the wild, some foragers mistake the two deadly species for edible puffballs.

Sometimes destroying angels are mistaken for edible puffballs (shown here). (Christianne Hacault/Radio Canada)

Both varieties contains the same amatoxins, which cause organ failure and neurological problems. Just half a mushroom cap can kill a healthy adult.

According to Booth, destroying angels are "extremely common" in Manitoba.

They can be found all over the province but are especially common in eastern areas like Sandilands and Whiteshell provincial parks, as well as in the Mars Hill area of the Interlake.

Destroying angels have a few distinguishing characteristics to watch out for, said Booth.

Very often foragers note a "series of loose flecks on the top of the cap that come from a veil that surrounds the entire mushroom when it's in a button stage," he said.

The flecks are the remnants of the ruptured veil that bursts as the fungi matures. Another sign to watch for is a ring around the stem which actually contains the bulk of the toxins in the mushroom, said Booth.

The last feature is what's called a volva — a cup at the base of the stem, he said. The volva is located under the soil.

While three key features are definite warning signs, only experienced foragers should be hunting for mushrooms, said Booth.

"Know your onions," he said. "Take care when you're looking for mushrooms."