dead man's fingers

Description

Dead man's fingers has no cap and no gills. Its fruiting body is a hard, corky stroma shaped like a club, finger or strap, usually 3–10 cm tall and about 2.5 cm thick. In spring it is pale, with a white tip and a grey coating of spores, then it darkens until it becomes black and wrinkled. Inside it is white and fibrous. Hence its English name "dead man's fingers".

It grows all year round, singly or in hand-like clusters, on dead hardwood: stumps, roots and rotting trunks, especially of beech and oak. It sometimes grows from wood hidden in the soil and then looks as if it were growing straight from the ground. It is common in Poland.

The black, hardened stroma on wood distinguishes it from cap-and-stem mushrooms. It is inedible. It is easily confused with similar Xylaria species (e.g. Xylaria longipes), but none of them is fit to eat.

Identification features

Cap

No cap; the fruiting body is a stroma of variable shape: club-shaped, mace-shaped or strap-shaped, upright, often growing singly or in clusters resembling fingers, sometimes fused together. Height usually 3–10 cm, thickness about 2.5 cm. The surface is granular; in young specimens in spring it is pale with a white tip, often greyish from spores, then gradually darker, finally black and wrinkled (brown or black, sometimes with a bluish or greenish tinge).

Hymenophore (underside of the cap)

No gills or tubes. The spore-bearing perithecia are embedded in the surface layer of the stroma, and their openings are visible as tiny dots; the ascospores escape through the opening at the top of the perithecium.

Stem

No distinct stem; the stroma grows directly from the wood or has a short, narrowed base. No ring.

Flesh

White inside, fibrous, hard and corky, with a black, dotted zone just beneath the surface formed by the perithecia. Taste and smell are not described as distinguishing features; the flesh should not be tasted.

Spore print and spores

Spore print black. Ascospores 20–32 × 5–9 µm, produced in summer and autumn in the teleomorph. In the anamorphic stage (spring), greenish-grey conidia measuring 10–13 × 6–7 µm are produced, forming a grey coating on the stroma.

Habitat and distribution

Ecology. Saprotroph, causing wood decay. Grows on dead hardwood, stumps and roots, especially of beech and oak, usually at the base of rotting or damaged trunks. It sometimes grows from wood buried in the soil and appears to grow from the ground. Also recorded on woody legume pods, leaf stalks and stems of herbaceous plants.

Distribution. Cosmopolitan species, recorded on all continents except Antarctica (sources differ on its presence in Africa). Common in Poland, in forests and wooded areas. Not legally protected in Poland.

Fruiting. The stromata persist throughout the year. The conidial stage is visible in spring, while the teleomorph with ascospores matures in summer and autumn.

What can it be confused with?

• Xylaria longipes (Polish: próchnilec długotrzonkowy) — More slender stromata; grows mainly on dead maple branches.
• Xylaria hypoxylon (Polish: próchnilec gałązkowaty) — Much smaller, with thin, branched stromata with a white, powdery tip.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The species epithet polymorpha means "of many forms": the fruiting bodies may be club-shaped, finger-like, strap-shaped or fused together.
• The English name "dead man's fingers" refers to the black, finger-like stromata growing out of the ground or wood.
• The species has two stages: asexual conidia form in spring, and sexual ascospores in summer and autumn. Spore dispersal can last several months.
• The Polish genus name "próchnilec" (from "próchnienie", rot) refers to the fact that fungi of this genus cause wood decay.