European genera belonging to Xylariaceae Tul. & C. Tul. exhibit a wide
range of morphological variations that are to be illustrated in the present
work. Xylariaceae is a family in which, besides outstanding
variations in morphological features, the
combination of the following characters is shared by all genera :
perithecia enclosed in (or covered by) a stroma, unitunicate asci with
an apical apparatus which is frequently bluing in Melzer's reagent (amyloid), paraphysate
hamathecium and brown ellipsoid ascospores which are usually one-celled and
provided with a germ slit or a germ pore.
Stromatal morphology and structure, situation of the perithecia within the
stroma and identification of anamorphs are the main characters used in separating
xylariaceous genera. At the specific level, ascospores characters are frequently
the most discriminant ones, along with morphological and chemical characters
of the stromata.
Before the taxonomic treatment of each genus, a key to the
genera formerly classified as Hypoxylon and other xylariaceous genera
is proposed, after the more complete keys proposed by
Ju & Rogers (1996) and
Rogers & Ju (1998).