Source : Webster's Revised Unabridged Dictionary (1913)

Ascomycetes \As`co*my*ce"tes\, n. pl. [NL.; ascus + Gr. ?, ?,
   fungus.] (Bot.)
   A large class of higher fungi distinguished by septate
   hyph[ae], and by having their spores formed in asci, or spore
   sacs. It comprises many orders, among which are the yeasts,
   molds, mildews, truffles, morels, etc. -- {As`co*my*ce"tous},
   a.

Source : WordNet®

ascomycetous
     adj : related to or characteristic of fungi of the class
           Ascomycetes