April Haight, 4, poses with a giant mushroom known as Bondarzewia berkeleyi, which is a polypore or shelf mushroom. The mushroom, in North Lawrence, weighs more than 15 pounds.

An unusually large and rare mushroom has reappeared for a second year in North Lawrence.

At the base of a white oak tree that stands 65 feet or so rests a 2-and-a-half-foot wide polypore mushroom. It weighs more than 15 pounds. The mushroom is uncommon in the area and has been a wonder to those who have seen it.

“I didn’t know mushrooms grew that large,” said Jennifer Haight, a recent visitor to the mushroom in a residential area.

Hank Guarisco, Lawrence resident and adjunct curator of arachnids at Fort Hays State University, has given personal tours of the mushroom since it was brought to his attention last summer by the property owner.

On July 1, he led friend Haight and her daughter, April Haight, 4, to see the “wild-looking thing,” he said.

“It was like a special field trip to see an oddity in Lawrence,” Jennifer Haight said.

In late June and early July, the mushroom was cream-colored, its several lobes overlapping, blossoming like a large flower. Now, it’s a pile of brown moldy fungus that’s attracting more flies than people. And it smells like rotting vegetation.

“It is really big and beautiful when it’s fresh,” said Sherry Kay, secretary and founder of the Kaw Valley Mycological Society, who identified the mushroom last year.

The mushroom was first noticed last summer by the property owner, Dan Bentley.

He purchased the house east of his last year and noticed the growing mushroom on the south side of the white oak tree when he was mowing.

“I saw it come out originally,” he said. “It was real small, and then it kept getting bigger and bigger. : I didn’t think it would get that big.”

When it got to be about 15 pounds and measured two feet across, he called on his friend Guarisco to check it out. Guarisco alerted Kay.

Kay identified the mushroom as Bondarzewia berkeleyi. It has been identified in New Zealand, Sri Lanka, New Guinea, Europe and China, according to Guarisco’s research. The mushroom is generally found in the eastern half of the United States. The berkeleyi mushroom is often found at the base of oak trees and – because they are parasites – eventually will cause the tree to rot and hollow out.

The mushroom reappeared on the north side of the tree this summer and grew even larger than last year. It will likely continue to reappear.

“This was pretty amazing,” Kay said. “It hadn’t been seen in Kansas for 50 to 75 years.”

She said she was surprised to see it growing on an oak tree in Lawrence, because the mushroom is typically found in thicker woods.

Guarisco and Kay co-authored a brief journal article on the reappearance of the mushroom for the Kansas Academy of Science.

In its early stages, the mushroom is edible, but Bentley wouldn’t recommend that now.

“It kind of left a nasty taste in your mouth,” he said. “You’d have to be desperate to use it for food.”