In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. Anamorph: an asexual reproductive stage (morph), often mold-like. When a single fungus produces multiple morphologically distinct anamorphs, these are called synanamorphs. Holomorph: the whole fungus, including anamorphs and teleomorph. Dual naming of fungi Fungi are classified primarily based on the structures associated with sexual reproduction, which tend to be evolutionarily conserved. However, many fungi reproduce only asexually, and cannot easily be classified based on sexual characteristics; some produce both asexual and sexual states. These problematic species are often members of the Ascomycota, but a few of them belong to the Basidiomycota. Even among fungi that reproduce both sexually and asexually, often only one method of reproduction can be observed at a specific point in time or under specific conditions. Additionally, fungi typically grow in mixed colonies and sporulate amongst each other. These facts have made it very difficult to link the various states of the same fungus. Fungi that are not known to produce a teleomorph were historically placed into an artificial phylum, the "Deuteromycota," also known as "fungi imperfecti," simply for convenience. Some workers hold that this is an obsolete concept, and that molecular phylogeny allows accurate placement of species which are known from only part of their life cycle. Others retain the term "deuteromycetes," but give it a lowercase "d" and no taxonomic rank. Historically, Article 59 of the International Code of Botanical Nomenclature permitted mycologists to give asexually reproducing fungi (anamorphs) separate names from their sexual states (teleomorphs); but this practice was discontinued as of 1 January 2013. The dual naming system can be confusing for novices. It is essential for workers in plant pathology, mold identification, medical mycology, and food microbiology, fields in which asexually reproducing fungi are commonly encountered. From dual system to single nomenclature The separate names for anamorphs of fungi with a pleomorphic life-cycle has been an issue of debate since the phenomenon was recognized in the mid-19th century. This was even before the first international rules for botanical nomenclature were issued in 1867. Special provisions are to be found in the earliest Codes, which were then modified several times, and often substantially. The rules have been updated regularly and become increasingly complex, and by the mid-1970s they were being