QUESTION
A group of us have owned a camp at the mouth of the Steel River on Lake Superior (near Terrace Bay) since 1968. Although we've been beachcombing for years, it wasn't until two summers ago that we discovered some strange stone-like growths. I've enclosed the largest. They seem to be composed of sand particles cemented together, and yet they have developed upward into this fungus-like shape. We found them growing upright on a small dead birch limb and a decaying black spruce log. Can you identify them for us?

ANSWER

It seems you've found a most uncommon fungus called Polyporus tuberaster, a.k.a. the "stone fungus," and sometimes called a tuckahoe (although just to confuse things, other species of fungus are also called tuckahoes).

The Royal Ontario Museum's John Krug believes that the stony portion you picked up is the so-called sclerotium of the fungus - a compact mass formed from the living mycelium (or vegetative part), which mix with soil or sand as they grow, and become cemented together. Originally rather tough and fleshy, the sclerotium would have shrunk as it dried, becoming the stone-like mass you found.

Polyporus tuberaster grows in soil rather than on dead trees, and normally most or all of the mycelium is underground, so Krug suggests that it may have grown up out of the ground and, coincidentally, onto the fallen limbs.

Dead as they seem to be, when planted and watered these fungus stones are capable of producing a new fruiting body, i.e. a fresh mushroom that is eaten in some European countries. But they are unusual enough in these parts that Krug has asked to keep a piece of the Terrace Bay tuckahoe for the ROM's permanent collection.

* Published in the June 2004 issue of Cottage Life