Hypoxylon sassafras (Schwein.: Fr.) M. A. Curtis has long been considered to be a Hypoxylon and described under this name by Miller (1961) and Petrini and Müller (1986). Indeed it shared most of distinctive features of this genus as defined by these authors, until it was segregated from Hypoxylon by Ju et al. (1993) who resurrected the genus Creosphaeria Theiss. to accommodate it.

Hypoxylon sassafras, as most of Hypoxylon taxa retained by Ju and Rogers (1996), has lignicolous waxy stromata with orange granules yielding orange pigments in 10% KOH, asci provided with an amyloid apical ring and brown ellipsoid ascospores with a germ slit. But unlike Hypoxylon which is defined as having Nodulisporium Preuss anamorphs, cultures undertaken by Petrini and Müller (1986) and Ju et al. (1993) proved that H. sassafras has a Libertella Desm. anamorph, that is characteric of Diatrypaceae Nitschke and of some other xylariaceous genera of uncertain position [Lopadostoma (Nitschke) Traverso, Ju et al. (1993), Barrmaelia Rappaz (1995)].

Moreover, it differs from most Hypoxylon taxa in being usually uniperitheciate, although stromata are frequently found fused together, and in having large perithecia frequently more than 1 mm diam in solitary stromata.

As far as known (Ju et al., 1993) Creosphaeria is a monospecific genus, although C. sassafras has a worldwide distribution and has been described under a lot of different names. For synonymy, the reader is referred to Miller (1961) and to Ju et al. (1993).