Hypoxylon fragiforme

Hypoxylon fragiforme is a multiperitheciate carbonaceous pyrenomycete known from Europe and North America.

Description
It is saprobic on wood, mostly beech. The semispherical lumps are up to 15 mm wide and covered with 15–25 bumps in maturity. The flesh is hard and black. Specimens are reddish when young, and they produce orange pigments when mixed with KOH.

Similar species
Similar species include Hypoxylon howeianum, which can be differentiated microscopically by smaller ascospores. The anamorph of H. fragiforme sits on a fuzzy green subiculum while the anamorph of H. howeianum sits on radiating hyphal cords, reminiscent of a white spiderweb-like structure.

Other similar species exist within Annulohypoxylon, Nemania, and Rosellinia.