The Carlisle Mosquito Online

Friday, September 21, 2007


Biodiversity Corner - Blackening polypore

It has been a dry summer. Mushroom hunters would describe it as pitiful, pathetic and a summer of paucity but on Monday, September 10, the Mosquito office sent me a message from Nancy Pisiello of East Riding Drive about an "ottoman-sized" mushroom in her back yard. It had been there for a couple of weeks under the hydrangea bushes at the back of the house.
Nancy Pisiello of East Riding Drive inspects her "ottoman-sized" blackening polyphore. (Photo by Kay Fairweather)

Name.The blackening polypore is Meripilus giganteus or perhaps Meripilus sumstinei. The mushroom guides differ. It is called a polypore because the fertile surface on the underside of each frond has many pores. The blackening refers to the change in color of the pore surface when bruised.

Identification. The blackening polypore has many overlapping fronds coming from a common base. The fronds are tan and dull yellow and generally have concentric zones. The pore surface is white. As you might guess from the giganteus name, these things can be large. Nancy's was about three feet in diameter and a foot and a half tall.

Habitat. Polypore mushrooms are the fruiting bodies of fungi that decompose wood. The blackening polypore is reputed to prefer oak and beech but can be found on other hardwoods. It is usually at the base of a tree or on a stump. Sometimes in nature you find a renegade specimen that hasn't read the field guides and doesn't know what it should be doing. This mushroom was one of those. It was not near any hardwoods — the nearest trees were pines and even those were not very close. Sometimes a mushroom that appears to be growing on the ground is coming from a buried stump or roots. Nancy can vouch for this location, having lived there for over thirty years, and there are no buried stumps in the area. I find it hard to believe that there would be enough substance in the hydrangeas to sustain a fungus which could produce this large a mushroom — and the hydrangeas looked very healthy.

Other massive mushrooms. Berkeley's polypore is also a gigantic mushroom and composed of many fronds with concentric zoning. The fronds are fewer and thicker than on the blackening polypore. Last year there was one at Great Brook Farm State Park at the edge of the parking lot at the canoe launch. The very tasty hen of the woods mushroom is another large polypore with many fronds that can reach a span of two feet and is sometimes confused with the blackening polypore. It tends to have a more gray look and the fronds are smaller, thinner, and wavier than the blackening polypore. Both of these look-alike species have the same habitat as the blackening polypore.

Edibility. I have a friend who ate some of a blackening polypore thinking it was a hen of the woods and had no ill effects. The books list the blackening polypore as "edible" where the hen of the woods is listed as "edible and choice." Nancy's mushroom was too old and tough to be worth trying. Berkeley's polypore is described as edible when young but tough and bitter when old.

References. Mushrooms of North America, Roger Phillips; Mushrooms of Northeastern North America, Alan Bessette, Arleen Bessette, David Fischer; Mushrooms Demystified, David Arora.

Submissions for the Biodiversity Corner are encouraged from everyone. What are you finding? Send a note to Kay Fairweather at 392 School St., Carlisle MA 01741 or to


2007 The Carlisle Mosquito