The Collaborative International Dictionary of English v.0.48:

Xylaria \Xy*la"ria\, pr. n.
   The type genus of the natural family Xylariaceae; fungi
   with perithecia in the upper part of erect black woody
   stromata.

   Syn: genus Xylaria.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Xylaria
    n 1: type genus of Xylariaceae; fungi with perithecia in the
         upper part of erect black woody stromata [syn: Xylaria,
         genus Xylaria]