By BILL KETTLER

Gordon Larum noticed an unusual mushroom when he was walking down East Main Street last week.

The veteran mushroom forager didn't need much time to identify the fungus. With its shiny, yellow-green cap, cream-white stem and strong aroma he could see it was the death cap, a deadly mushroom that he had never seen in Medford.

"I was amazed," Larum said. "In 23 years of looking for fungi here, it hadn't turned up."

One of the most lethal mushrooms, the death cap (Amanita phalloides) is a European native that has been found in scattered locations on the Pacific Coast over the years. It was discovered in Ashland's Lithia Park several years ago and has been identified around San Francisco, Vancouver, Wash., and Victoria, British Columbia.

The death cap is reportedly delicious, but attacks the liver of people who eat it. Symptoms may not appear until 72 hours after ingesting the fungus, making treatment difficult. Some people have survived a taste of phalloides only by receiving a liver transplant.

"This is by far the most notorious and most feared" poisonous mushroom, Larum said.

Like other mushrooms, phalloides reproduces and spreads from microscopic spores that are the fungal equivalent of seeds. The spores produce a network of microscopic threads (the mycelium) that may live in soil for years before a mushroom emerges above ground.

Larum said phalloides spores may have hitched a ride into Medford in the root balls of nursery stock because he found the mushroom growing beside a non-native birch tree.

Other mycologists also have found phalloides associated with imported plants, said Janet Lindgren, president of the Oregon Mycological Society. "Quite a lot have been traced to chestnuts and filberts and other foreign plant material," she said.

Lindgren said phalloides appears to be expanding its range, but it's hard to say with certainty because scientists know so little about how mushrooms grow.

"We're finding more of them," she said, "but we're not sure if it's because more of us are more aware of what it looks like or if it's had more growing time."

It's impossible to know when Amanita phalloides arrived in Medford, said Larum. "Sometimes it takes 10 to 20 years before a fruiting body (mushroom) appears."

He said the birch tree growing beside the mushroom he found appeared to be 15 to 20 years old.

Larum said the vast majority of mushrooms are not poisonous, but it's important to know that some can be deadly.

"You can't just go foraging indiscriminately for mushrooms," he said. "If you don't know what it is, don't eat it."

Ashland officials have attempted to slow phalloides' spread in Lithia Park and protect mushroom foragers from accidentally collecting them by picking the mushrooms as they appear and discarding them.

Park horticulturist Donn Todt said workers have found only a few of the deadly mushrooms this fall, "but I don't know if (picking) does anything. The mycelium is still there. "I think they're here for good."