Cramp Balls

Cramp Balls © SBernhard

Annulohypoxylon thouarsianum

This bulbous, carbon-like fungus with a pimpled surface thrives on coast live oak, standing out in scattered or clustered groups.

Appearance

  • Black, carbon-like sphere, 1-5 cm. wide and up to 3 cm. tall
  • Pimpled surface with tips surrounded by a small, flat disc
  • Without a stipe (stem)
  • Grows scattered or clustered

ID Tips

  • May be confused with another fungus also called cramp balls (Daldinia grandis); its presence in California is questioned

At Edgewood

About

  • Ascomycetes – a major lineage of fungi that usually produce spores within asci (sac-like structures)
  • Found throughout the year
  • Saprotrophic – common on coast live oak (Quercus agrifolia) and tanoak (Notholithocarpus densiflora), the latter not found at Edgewood
  • Edibility (San Mateo County Parks prohibits removal of any natural material)
    • Inedible; too tough and woody
    • Unless you are an expert, do not pick and consume wild mushrooms

Learn More

Roehl, T. 2016, Nov. 7. #012: Characteristics of phylum Ascomycota. Fungus Fact List. Fungus Fact Friday.

Roehl, T. 2017, Jul. 7. #039: Mushroom morphology: Crust fungi. Fungus Fact List. Fungus Fact Friday.

References

Desjardin, D.E., M.G. Wood, and F.A. Stevens. 2016. California Mushrooms: The Comprehensive Identification Guide. Timber Press, Portland, Oregon.

Wood, M., and F. Stevens. 2020. Annulohypoxylon thouarsianum. The Fungi of California. MykoWeb.