Friday, October 27, 2006
Dead man's foot
This time of year you are likely to see all manner of shocking things — whether part of Halloween celebrations or election campaign tactics. There is a man buried head-first up to his waist on the corner of Church Street and School Street. If he wasn't wearing sneakers and was buried up to his ankles, he might resemble my topic for this week. Dead Man's Foot is a mushroom with the binomial, Pisolithus tinctorius where Pisolithus means pea-stone (more on that later) and tinctorius means capable of dyeing. It is also known as the dye-makers false puffball or just dye-ball and it makes a dark brown dye for wool. It is neither a true puffball like the giant white puffball in the lawn, nor an earthball like the pigskin poison puffball. For want of a better name David Arora of Mushrooms Demystified calls them oddballs.
When and where found. I found a Dead Man's Foot in my front yard protruding through the area where I spread the pebbles that I dig out of the garden. That was on July 16 and was the first and so far only one I have found in Carlisle. The Audubon Guide says they can be found from July through October. Last weekend I found several large specimens in sandy soil at the Marconi Station near Wellfleet on Cape Cod. The one in my yard and the ones on the Cape were all growing in full sun. You won't find them in rich humous soil in the woods. The preferred habitat is poor soil, sand, and gravel. Hard-pack is not a problem — they can even push their way through pavement.
Distinguishing characteristics. You are most likely to notice a Dead Man's Foot when it is mature and the outer surface has decomposed to reveal a crumbly brown mass of spores. You can guess how big this mushroom gets to be — yes, about a foot long. It is a club-shaped lump as if the man had been dead a long time. It has no distinguishable toes but if it did, you can be sure there would be fungus between them. The spores are contained in distinct capsules called peridioles, so the mushroom looks like a container full of pea-stones, hence Pisolithus. If you make a vertical slice down through the mushroom, you will see layers of peridioles starting with the most mature at the top. This is the best confirmation that the mushroom is a Dead Man's Foot. When the mushroom is young, the peridioles are encased in black jelly. David Arora likens this stage to "Rice Krispies in tar." When the top layer of peridioles is fully mature and releasing spores, it is brown and dry with no sign of tar or jelly. The next layer is nearly black and the one below that is pale yellow and still moist. The younger, moister parts will stain your fingers.
Reforestation. There is much more good in the Dead Man's Foot than the dye, and the thrill of seeing the beautiful layers of peridioles. The fungus is mycorrhizal which means that it forms a close and mutually beneficial association with tree roots (in this case mainly pine). The fungus forms a coating around the rootlets of the tree and helps the tree absorb phosphorus, inorganic nitrogen, various minerals and trace elements. In turn the fungus get moisture and carbohydrates. Trees with mycorrhizal fungi are healthier than those without. Since Dead Man's Foot likes impoverished soil and can tolerate drought, it will grow where other mycorrhizal fungi won't. Therefore it is used to inoculate tree seedlings that are destined for reforestation projects in mine tailings, sandy soils and other similarly difficult habitats.
References. David Arora, Mushrooms Demystified; Else Vellinga, Mycena News, Mycological Society of San Francisco, May 2006; Gary Lincoff, Audubon Field Guide to Mushrooms of North America.
Submissions and ideas for the Biodiversity Corner are encouraged on any wildlife in town. Send a note to Kay Fairweather at 392 School St, Carlisle MA 01741 or to firstname.lastname@example.org
© 2006 The Carlisle Mosquito