The corticioid fungi are a group of

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

in the

Basidiomycota Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...

typically having effused, smooth

basidiocarps In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp (fungi), sporocarp of a basidiomycota, basidiomycete, the Multicellular organism, multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are chara ...

(fruit bodies) that are formed on the undersides of dead tree trunks or branches. They are sometimes colloquially called crust fungi or patch fungi. Originally such fungi were referred to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' Corticium'' ("corticioid" means ''Corticium''-like) and subsequently to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Corticiaceae The Corticiaceae are a family of fungi in the order Corticiales. The family formerly included almost all the corticioid (patch- or crust-forming) fungi, whether they were related or not, and as such was highly artificial. In its current sense, ...

'', but it is now known that all corticioid species are not necessarily closely related. The fact that they look similar is an example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

. Since they are often studied as a group, it is convenient to retain the informal (non-taxonomic) name of "corticioid fungi" and this term is frequently used in research papersLarsson K-H, Larsson E, Koljalg U. (2004). High phylogenetic diversity among corticioid homobasidiomycetes. ''Mycological Research'' 108: 983–1002. and other texts.

History

The genus ''Corticium'' was established by

Persoon Christiaan Hendrik Persoon (1 February 1761 – 16 November 1836) was a German mycologist who made additions to Linnaeus' mushroom taxonomy. Early life Persoon was born in South Africa at the Cape of Good Hope, the third child of an immig ...

in 1794 for fungi having smooth, effused fruit bodies. ''

Corticium roseum ''Corticium roseum'' is a species of fungus in the family Corticiaceae. Basidiocarps (fruit bodies) are effused, smooth, corticioid, and pink. The species has a wide, north and south temperate distribution and in Europe is typically found on dead ...

'' Pers. was later selected as the type species. Subsequent authors described over 1000 species in the genus which continued to be used in its wide sense up until the 1950s. Though a number of genera had been recognized as distinct from ''Corticium'' from the late nineteenth century onwards, it was not until Swedish mycologist Prof. John Eriksson reviewed the corticioid fungi in a series of publications starting in 1950 that modern concepts were formed. The eight-volume work that he initiated, ''Corticiaceae of North Europe'' (1973-1987), effectively established the current circumscription of the corticioid fungi. Eriksson and his co-authors, however, still placed all or most of these fungi within the ''Corticiaceae'', though stating that this was "not a natural taxon but an assemblage of species with similar habitat."Hjortstam K, Larsson K-H, Ryvarden L. (1987). ''The Corticiaceae of North Europe''. Vol. 1. Oslo: Fungiflora It was not until the advent of DNA sequencing that the full diversity of these fungi was realized. The genus ''Corticium'' is still retained, but is now restricted to a few species closely related to the type. The ''Corticiaceae'' is now equally restricted to a few genera close to (and including) ''Corticium''. Crust-like species are found in no less than 18 of the 24 currently recognized orders of higher basidiomycetes (Agaricomycotina).

Description and diversity

Corticioid fungi are rather loosely defined, but most have effused fruit bodies, the spore bearing surface typically being smooth to granular or spiny. Some species (in the genera ''

Stereum ''Stereum'' is the type genus of the Stereaceae family of fungi, in the Russulales order. Until recently, the genus was classified in the Corticiaceae family, of the Corticiales order. However, it was given its own family as a result of the spli ...

'' and ''

Steccherinum ''Steccherinum'' is a widely distributed genus of toothed crust fungi in the family Steccherinaceae. Taxonomy ''Steccherinum'' was circumscribed by Samuel Frederick Gray in his 1821 work ''A Natural Arrangement of British Plants''. Descripti ...

'', for example) may form fruit bodies that are partly bracket- or shelf-like with a smooth to spiny undersurface. The corticioid fungi currently comprise around 1700 species worldwide, distributed amongst some 250 genera.Hjortstam K. (1998) A checklist to genera and species of corticioid fungi. ''Windahlia'' 23: 1–54. They constitute around 13% of the homobasidiomycetes known to date.

Habitat and distribution

Most corticioid fungi are wood-rotting species and rely on wood degradation as their primary means of nutrition. Although the fruiting bodies are formed on the underside of dead branches or logs, the fungus resides within the wood. A number of species are litter-rotting and produce fruitbodies underneath fallen leaves and compacted litter as well as on fallen wood. Some of these species are known to be

ectomycorrhizal An ectomycorrhiza (from Greek ἐκτός ', "outside", μύκης ', "fungus", and ῥίζα ', "root"; pl. ectomycorrhizas or ectomycorrhizae, abbreviated EcM) is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobi ...

(forming a beneficial association with the roots of living trees). A few specialist species grow on dead herbaceous stems and leaves or on dead grass, rush, and sedge stems, especially in marshes. Parasites of plants and other fungi are also found in the group. Corticioid fungi have a worldwide distribution, but are commonest in forest communities.

References

{{reflist Basidiomycota Mushroom types