September 11th, 2010


50 More Urban Species #33: Jack-O-Lantern Mushroom

Jack-o-lantern mushroom Omphalotus olearius illudens

Sometimes naturalists like to describe an organism as "unmistakable," without properly respecting the human tendency to make mistakes. I think of this mushroom species as unmistakable, yet tales of poisonings insist that mistakes have been made. The biggest error of someone hunting mushrooms for food is wishful thinking--wanting something so bad as to ignore signs that things aren't what they are.

Another common error is choosing one identifying characteristic to stand the whole identification. These are orange. Chanterelles can be orange. The gills of this mushroom descend somewhat, from the cap down the stalk (they are decurrent). The gill-like folds of a chanterelle descend the stalk. These mushrooms are growing apparently from the ground, as the mycorrhyzal chantarelles do. And yet to claim these as chanterelles (which has happened, and why people have been poisoned by this species) is to willfully ignore signs that these clearly aren't.

The cap and stem are distinct parts here, even with the decurrent gills. While there is a surprising variety of shapes within this one cluster of mushrooms, none of them are remotely vase-shaped, the signature field marking of a chanterelle. And while lucky chanterelle hunters may find clusters of their preferred mushroom, they will not find them all sharing the same stalk, as these do.

Jack-o-lantern mushroom is the name for a group of orange mushroom species: one found in Europe, one in the Southeast U.S., one in the western states, and this one, native to the Northeast and Central state. All are toxic, with at least two toxic chemicals identified in their flesh. One of these chemicals is illudin, which interests science both for its antitumor properties and its bioluminescence. The fact that this mushroom's gills glow in the dark, and has orange flesh are the reasons for the common name. Although Michael Kuo has a serious beef with the whole bioluminescence deal. Suffice it to say, it has to be a whole lot darker than it typically gets in a city to rely on glowing gills as a field marking. (Tom Volk provides the evidence here.)

The fungus that produces this mushroom feeds on the dead roots of trees, especially oaks. Often times, as in this case, the tree in question has been cut down and hauled off as firewood, possibly years ago. There isn't even a stump, but the mycelium lives on in the buried roots, producing mushrooms to reproduce as it uses up its finite food source.