The Carlisle Mosquito Online

Friday, August 25, 2006


The pigskin poison puffball (right) is host to the parasitic mushroom Boletus parasiticus. (Photo by Kay Fairweather)

Biodiversity Corner:
Pigskin Poison Puffball

I was in the Towle Woods on Sunday and found mushrooms of many colors: a solitary, succulent blood-colored beefsteak mushroom, yellow and orange chicken-of-the-woods, some shiny purple ones, mottled green ones, and the usual line-up of off-white, brown and tawny ones. To take our minds off baseball and to celebrate the start of the NFL season I thought the tawny brawny pigskin puffball would do the trick.

Name: Scleroderma citrinum, aka Scleroderma aurantium.Its common name is Pigskin Poison Puffball — nicely alliterative but not quite accurate. Sclerodermas are not true puffballs; they are collectively referred to as "earthballs." The term sclero means hard and derma means skin, making these the hard-skinned earthballs. (Scleroderma is also the name of a chronic disease of human connective tissue, for which one of the characteristics is hardening of the skin.) Poison pigskin puffballs belong to the class Gasteromycetes or stomach fungi, so named because the spores are produced completely inside the fruiting body.

When and where seen: The pigskin poison puffball is the most common of the Sclerodermas. It has been showing up since around the start of pre-season football and as we approach the start of the regular season it is popping up all over town. There are a lot at the North Road parking lot just beyond the canoe launch, several beside the path to the field from the Towle parking lot, and lots in the Conant Land. Some are growing on logs or stumps and some are right on the ground. Unlike many mushrooms, they are quite durable. The tough skin allows them to keep a recognizable form for several weeks.

Specimens of Sclerodermas are cut in half to show the thickness of the skin. The one on the right is very young and still white inside. (Photo by Kay Fairweather)

Distinguishing characteristics: Pigskin poison puffballs are roundish or somewhat oval, anywhere from one to four inches in diameter and a bit flattened. They have a tough, thick yellowish-brown skin with a pleasing pattern of scales that looks a bit like a mosaic. Each scale often has a wart in the center — the result is more attractive than it sounds.

When very young, the spore mass inside is firm and white but quickly changes to purplish black while still very firm. The spores finally turn brownish black and powdery and escape through an irregular shaped pore. True puffballs have thinner skins, and the spore mass softens considerably as it changes from white to various army camouflage colors.

Pox on the pigskin: Pigskin poison puffball is host to a parasitic mushroom called Boletus parasiticus. Mushrooms in the genus Boletus have tubes under the cap where other mushrooms have gills. If you see a mushroom like this growing directly out of a puffball, then each identifies the other since Boletus parasiticus fruits exclusively on Scleroderma citrinum. I found one recently at Great Brook Farm State Park.

Edibility: The common name is a good clue! These are poisonous — even when white inside. There is an old wives tale that says puffballs are edible if they are white inside. It has some elements of truth but more accurately stated it would say that true puffballs of species known to be edible are edible only when white inside. Alternatively the tale could be completely replaced with: "If you want to eat wild mushrooms, learn to identify them. If you are feeling lucky, buy a lottery ticket." Pigskin poison puffballs have been used occasionally to adulterate truffles. For those of us on low-truffle diets this is not a big worry.

References: David Arora, Mushrooms Demystified; Gary Lincoff, National Audubon Society Field Guide to North American Mushrooms; Roy Watling, Fungi.

Feel free to take this space and write up a species of your choosing. The only requirements are that the subject exists in the wild and was seen in Carlisle. Send it (or your ideas, sightings or photos) to Kay Fairweather at

2006 The Carlisle Mosquito