The Deuteromycetes or Mitosporic Fungi (Fungi Imperfecti) make up the higher fungi, with Ascomycetes and Basidiomycetes.

The higher fungi are eukaryotic organisms (organisms having a true intracellular nucleus, limited by a double membrane) that have chitinous cell walls. Their vegetative system is a thallus that is well developed, filamentous (= mycelium), and haploid or dikaryotic (cf. infra). They produce only non-motile spores (not zoospores that move by means of flagella). They are heterotrophic, that is, dependent for their energy needs on pre-formed organic matter that is dead (saprophytism) or living (parasitism, symbiosis).