E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features of Mycenastrum corium are 1) a medium to large, roundish fruitbody with a white outer layer that is felty becoming areolate [cracked like dried mud] forming thin grayish patches that wear away, exposing the inner case, 2) the inner case that is thick, tough, and brownish, eventually breaking into irregular lobes exposing the dark brown to purple-brown powdery spore mass, 3) absent sterile base (but mycelial fibers often present), 4) growth in pastures, horse corrals, barnyards, and composted areas, and 5) round warted-reticulate spores.

Mycenastrum corium is widely distributed but especially common in the west of North America, (Arora). It is widespread in North America, and often common in the Rocky Mountains, (McKnight). The species was examined from AZ: it is common in many parts of the United States, abundant in the west, and previously reported from CA, CO, FL, ID, IL, MI, MT, WY, Asia, Australia, Europe, India, Mexico, New Zealand, South Africa and South America, (Bates). There are collections from OR and CA at Oregon State University, and from BC at Pacific Forestry Centre and the University of British Columbia. It was reported from BC (in Redhead) and CA (Arora).

Outer Surface:
4-20cm or more across, spherical to somewhat pear-shaped when young, "eventually rupturing in irregular fissures to form rays or plates which may bend back somewhat in a star-shaped pattern"; outer layer of peridium (skin) thick, white, felty becoming areolate [cracked like dried mud], "forming thin, grayish, fibrillose patches which eventually wear away" to expose the inner layer, (Arora), 5-20cm across, comparatively thin felty outer layer breaks into patches or is shed, (McKnight)

Inner layer:
about 0.2cm thick, tough, hard, persistent, brown to purple-brown, smooth; the tough spore cases persist for months, sometimes blowing about in the wind, (Arora), thick, tough, persistent, white, eventually becomes pale dingy brownish and breaks into broad, irregular, somewhat star-like, somewhat recurved lobes, (McKnight)

Spore Mass:
"firm and white becoming olive-yellow to olive-brown and finally dark brown to purple-brown and powdery", (Arora), dark brown and powdery when mature (McKnight)

Stem:
sterile base "rudimentary or absent, but mycelial fibers often present", (Arora), no sterile base or stem (McKnight)

Odor:
unusual or mild (Miller)

Taste:
pleasant, mild, (Miller)

Microscopic:
spores 8-12 x 8-12 microns, round, warted-reticulate; capillitium branched, thorny, (Arora), spores 8-12 x 8-12 microns, round, warty, brown; capillitium thick-walled, branched, spiny, (McKnight)