Drenching monsoon rains have brought a bumper crop of mushrooms to mountain forests around Tucson - a boon for fungi fanciers but a poison peril for anyone who bites into a toxic species.

"It's an unusually good year for mushrooms, and the reason is moisture," said Chester Leathers, president of the Arizona Mushroom Club.

"That's the basic secret to mushrooms' success - plenty of moisture. This year the monsoon rains came and stayed, so we're seeing lots of mushrooms," said Leathers, who is a mycologist, or fungi specialist, and professor emeritus at Arizona State University.

Many forested areas of the Catalina Mountains north of Tucson are festooned with fungi this month - including mushrooms in assorted hues and sizes ranging from a small fingernail to a large fist.


Some wild mushrooms are edible, but many of the species are poisonous, Leathers warned.

"Eating toxic mushrooms can kill a person," he said, emphasizing that no one should eat a wild mushroom without being certain of its safety based on personal knowledge or advice from a mushroom expert.

"When in doubt, throw it out," Leathers said.

Some people have not followed that advice.

The Arizona Poison and Drug Information Center has handled 41 cases of ingestion of mushrooms this year - with 17 of those cases reported in August and seven so far in September.

"It was the busiest August (in terms of cases) since 2006," said Keith Boesen, director of the center.

Boesen said some of the reported cases of ingestion resulted in no symptoms - but others have brought about varying reactions.

"Mostly this year, it's been mainly mild symptoms such as feelings of nausea or vomiting," said Boesen, noting that there have been no fatal cases.

Toxic mushrooms in Arizona mountains include a red-capped mushroom known as the fly amanita, Leathers said.

"It is the most beautiful thing - almost a crimson or scarlet red with white scales over the cap," he said. "It's very poisonous."

Other poisonous species include the green-gilled parasol, he said.

Among the edible mushrooms is Caesar's amanita, which has a golden color.

About 25 percent or more of mushroom species contain toxins, Leathers estimated.

"Since the toxicity of all mushrooms is not known, I play it safe and say probably 15 percent of all the known mushrooms are edible - and the rest are unknown (as to toxicity) or definitely toxic," Leathers said.


About 500 species of wild mushrooms grow in Southern Arizona.

Source: Chester Leathers, president of the Arizona Mushroom Club

Contact reporter Doug Kreutz at dkreutz@azstarnet.com or at 573-4192. On Twitter: @DouglasKreutz