Xylaria polymorpha

Scientific name:  Xylaria polymorpha (Pers.) Grev.
Derivation of name: Xyl- means "woody." Poly- means
"several" or "many" and morph- refers to "shape" or
"form." Xylaria polymorpha is quite variable in form.
Synonyms:  Xylosphaera polymorpha (Pers.) Dumort,
Sphaeria polymorpha Pers.
Common name(s):  Dead mans fingers
Phylum:   Ascomycota
Order:   Xylariales
Family:   Xylariaceae
Occurrence on wood substrate:  Saprobic; clustered on
or near decaying hardwood; June through November
although the tough fruit bodies can be found year-round. 
Dimensions: Fruitbodies are 2.5 to 10 cm tall and can be
up to 4 cm thick.    
Description: These ascocarps are variable in shape from
cylindrical to knobby to branched or lobed. When found in
the spring they may be white to grayish and powdery as a
result of the formation of asexual spores. Later, they are
blackish and minutely pimply. The small bumps are the
locations of sexual spore producing structures called
perithecia. The perithecia are embedded in a tough white
flesh called the stroma.       
Edibility:  Not edible.
Comments: There are two other Xylaria species in the
Northeast that resemble X. polymorpha closely enough
that microscopic examination of the ascospores is
required to differentiate them. These are Xylaria longipes
and Xylaria schweinitzii. See the following websites for
more information.
 
More information at MushroomExpert.com:   
More information at TomVolkFungi.net:


Figure 1. Clustered fruitbodies arising from buried wood.
Photo © Gary Emberger.


Figure 2. Although appearing to grow on soil, these
fruitbodies are attached to a wood substrate. Photo ©
William Roody.

Figure 3. One ascocarp of this cluster on wood is broken open
to show the white stromal flesh. Photo © Gary Emberger.

Figure 4. In this closeup of the broken ascocarp in Figure 3.,
the dark perithecia embedded in the whte stroma just below
the surface are clearly visible.
Photo © Gary Emberger.

Figure 5. Each glistening perithecium forms asci and dark
brown to black ascospores. Photo © Gary Emberger.


Figure 6. One of the dead silver maple roots serving as a
substrate for Xylaria has been dug up and placed next to a
cluster of fruit bodies. Xylaria causes a white rot of wood,
decomposing both lignin and cellulose.
Photo © Gary Emberger.