Dead Man's Fingers

Dead Man’s Fingers, or Xylaria polymorpha, is a saprobic (saprophytic) and weakly parasitic fungus that is characterized by its club-shaped fruiting bodies that emerge from the soil in clusters such that it looks like a corpse’s hand is reaching up through the ground. As an ascomycete, it breaks down glucan in woody plants via the soft rot mechanism and can reproduce sexually or asexually. The scientific name refers to a species complex of several closely related species that cannot be easily distinguished. Hardwood trees that are susceptible to black root rot from infection include apple, crabapple, pear, cherry, plum, elm, maple, locust, oak, hickory, sassafras, walnut, and beech. It is inedible.

Taxonomy

X. polymorpha is in the phylum Ascomycota, which is commonly known as the sac fungi and is the largest phylum of fungi containing about 65,000 species. Furthermore, it is in the family Xylariaceae which is one of the largest and most diverse families of filamentous Ascomycota.

Xylaria means “growing on wood,” while polymorpha means “many forms.” Xylaria polymorpha is actually a species complex which may consist of anywhere from 5-10 species that are difficult to distinguish from each other.

Description

Dead Man’s Fingers are the mushroom-like fruiting bodies of X. polymorpha that can be found on or near dead or dying wood as well as wooden barrels that are in contact with the soil. The “fingers” of the fungus emerge from the ground either as a single fruiting body or as in groups of typically 3-6 which can be fused together. The form and number of fruiting bodies is highly variable. The fingers are usually 1-3 in. tall and ½ -1 ¼ in. wide. When young, the fungus is a pale white, gray, or blue with white caps that often resemble finger nails. As it matures, the fingers turn charcoal black and their smooth “skin” takes on the appearance of charcoal. If broken open, the interior of the fingers is white and tough. These fungi are active June through October but can found throughout the year. These fungi are not edible. Its spore print is dark brown to black, and when magnified, the spores appear as narrow and spindle-shaped, flat on one side.