What is "fungi imperfecti"

Fungi Imperfecti \Fun"gi Im`per*fec"ti\, pl. [L. imperfecti imperfect.] (Bot.) A heterogenous phylum of fungi which lack a sexual phase, or of which the sexual phase is not known. Some undoubtedly represent the conidium stages of various Ascomycetes. It is not considered a natural phylum, and is also called the Deuteromycota. The group is divided into the orders Sph[ae]ropsidales, Melanconiales, and Moniliales. It includes the genera Penicillium and Aspergillus, which reproduce asexually by means of conidia.

The Fungi imperfecti or imperfect fungi, also known as Deuteromycota, are fungi which do not fit into the commonly established taxonomic classifications of fungi that are based on biological species concepts or morphological characteristics of sexual structures because their sexual form of reproduction has never been observed; hence the name "imperfect fungi." Only their asexual form of reproduction is known, meaning that this group of fungi produces their spores asexually, in the process called sporogenesis.

There are about 25,000 species that have been classified in the deuteromycota and many are basidiomycota or ascomycota anamorphs. Fungi producing the antibiotic penicillin and those that cause athlete's foot and yeast infections are imperfect fungi. In addition, there are a number of edible imperfect fungi, including the ones that provide the distinctive characteristics of Roquefort and Camembert cheese.

Other, more informal, names besides Deuteromycota ("Deuteromycetes") and fungi imperfecti, are anamorphic fungi, or mitosporic fungi, but these are terms without taxonomic rank.