Group of Fungi: Polypores

Family: Hymenochaetaceae

Latin Name: Phellinus rimosus (Berk.) Pilát.

Synonym(s): Fomes rimosus (Berk.) Cooke

Common Name: Cracked-cap Polypore

Description: Semicircular, shelf-like or (more commonly) hoof-shaped structure; cap 2–12 in (5–30 cm) across and 3/4–2 in (2–5 cm) thick, upper surface brown, reddish brown to brownish black, with concentric furrows, becoming cracked, finely hairy, tough and woody; margin of cap rounded; spore-bearing surface yellow-brown to dark brown, pores very small and difficult to see; spores pale brown in mass.

Biological Role: Pathogen of living trees but also can be considered as a decomposer of wood when present on dead trees.

Habitat: On living and dead black locust trees; solitary or several fruiting bodies occurring together.

Geographical Distribution: Widely distributed throughout eastern North America wherever black locust occurs.

Comments: Because it is restricted to black locust trees, Phellinus rimosus is a very easy fungus to identify. The fruiting bodies are exceedingly hard and literally could be used in lieu of a hammer to drive a nail into wood!