ascomycete (noun, pl. ascomycetes; synonym: sac fungus) – a fungus that reproduces by ascospores formed within an ascus by an enveloping membranes system through a process called free cell formation. Many imperfect (= anamorphic, mitosporic) fungi can now also be assigned to the ascomycetes because of molecular evidence even though their sexual reproduction stages often remain unknown. In botanical classification of fungi the suffix "–mycetes" denotes the taxonomic rank of a class. Some modern classification systems, like the current outline of the Ascomycota (MYCONET), no longer recognize a separate class Ascomycetes. Instead, other groups have been elevated to this rank, e. g., the Arthoniomycetes, Lecanoromycetes, etc. Alternatively, the 9th edition of the Dictionary of Fungi () still treats Ascomycetes as a class and recognizes the same groups as subclasses, e. g., Arthoniomycetidae, Lecanoromycetidae, etc. No matter, which classification system is followed, the term ascomycetes is now relatively well established in common English language. In contrast, the trivial name sac fungi is rarely used. The spelling ascomycetes (not capitalized) should be used if the term is used informally in the sense of a common name. Otherwise, the term must be capitalized (Ascomycetes) to indicate that it refers to a class of organisms.