The hydnoid fungi are a group of

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

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 ...

with

basidiocarps In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do no ...

(fruit bodies) producing

spores In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plant ...

on pendant, tooth-like or spine-like projections. They are colloquially called tooth fungi. Originally such fungi were referred to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Hydnum ''Hydnum'' is a genus of fungi in the family Hydnaceae. They are notable for their unusual spore-bearing structures of teeth rather than Lamella (mycology), gills. The best known are the Edible mushroom, edible species ''Hydnum repandum'' and ''H ...

'' ("hydnoid" means ''Hydnum''-like), but it is now known that not all hydnoid species are closely related.

History

''Hydnum'' was one of the original genera created by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in his ''Species Plantarum'' of 1753. It contained all species of fungi with fruit bodies bearing pendant, tooth-like projections. Subsequent authors described around 900 species in the genus. With increasing use of the microscope, it became clear that not all tooth fungi were closely related and most ''Hydnum'' species were gradually moved to other genera. The Dutch

mycologist Mycology is the branch of biology concerned with the study of fungi, including their taxonomy, genetics, biochemical properties, and use by humans. Fungi can be a source of tinder, food, traditional medicine, as well as entheogens, poison, and ...

Rudolph Arnold Maas Geesteranus paid particular attention to the group, producing a series of papers reviewing the

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

of hydnoid fungi. The original genus ''Hydnum'' is still current, but is now restricted to the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, '' Hydnum repandum'', and its relatives in the order Cantharellales. Other species originally described in ''Hydnum'' have been reassigned to various genera in various orders including the

Agaricales The Agaricales are an order (biology), order of fungi in the division (mycology), division Basidiomycota. As originally conceived, the order contained all the agarics (gilled mushrooms), but subsequent research has shown that not all agarics are ...

Auriculariales The Auriculariales are an order of fungi in the class Agaricomycetes. Species within the order were formerly referred to the " heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps (fruit bodies) that produce spores on ...

Gomphales The Gomphales are an order of basidiomycete fungi. Some or all families belonging to Gomphales have been sometimes included in the order Phallales (and ''vice versa'' - they are also sometimes treated as synonyms), the now-obsolete Ramariacea ...

Hymenochaetales The Hymenochaetales are an order of fungi in the class Agaricomycetes. The order in its current sense is based on molecular research and not on any unifying morphological characteristics. According to one 2008 estimate, the Hymenochaetales con ...

Polyporales The Polyporales are an order (biology), order of about 1,800 species of fungi in the division (mycology), division Basidiomycota. The order includes some (but not all) polypores as well as many corticioid fungi and a few agarics (mainly in the ge ...

Russulales The Russulales are an order of the Agaricomycetes, (which include the agaric genera '' Russula'' and ''Lactarius'' and their polyporoid and corticioid relatives). According to the ''Dictionary of the Fungi'' (10th edition, 2008), the order con ...

Thelephorales The Thelephorales are an order of fungi in the class Agaricomycetes. The order includes corticioid and hydnoid fungi, together with a few polypores and clavarioid species. Most fungi within the Thelephorales are ectomycorrhizal. None is of ...

and

Trechisporales The Hydnodontaceae are a family of fungi in the class Agaricomycetes. According to a 2008 estimate, the family contains 15 genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification ...

Description and genera

The fruit bodies of hydnoid fungi are diverse, but all produce their spores on the surface of pendant, tooth-like or spine-like projections.

Stipitate hydnoid fungi

Some terrestrial species producing fruit bodies with a pileus (cap) and stipe (stem) are collectively known as the stipitate hydnoid fungi and are often studied as a group because of their ecological similarity. The species concerned are now referred to the genera '' Bankera'', '' Hydnellum'', '' Phellodon'', and '' Sarcodon''. All are ectomycorrhizal, belong in the

, and are considered to be

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

of old, species-rich forests. In Europe, at least, many are of conservation concern and feature on national or regional red lists of threatened fungal species. In the United Kingdom the stipitate hydnoid fungi have been given Biodiversity Action Plan status which has increased interest in the group and has generated funding to be put into survey work and other research. Species of ''

'' and the related ''Sistotrema confluens'' ( Cantharellales) are also mycorrhizal, but have different ecological requirements. Other stipitate hydnoid fungi are wood decomposing, such as some species of ''

Beenakia ''Beenakia'' is a genus of fungi in the Clavariadelphaceae The Clavariadelphaceae are a family of fungi belonging in what is classically known as the Gomphales order, or cladistically as the gomphoid-phalloid clade. First described by Britis ...

'' (Gomphales), '' Climacodon'' (Polyporales) and Mycorrhaphium (Polyporales).

Resupinate hydnoid fungi

The largest group of fungi formerly placed in the genus ''Hydnum'' are wood-rotting species, forming patch-like fruit bodies on dead attached branches, logs, stumps, and fallen wood. Species with small "teeth" (just a millimetre or so long) are sometimes described as "odontioid" (tooth-like). Species that form resupinate (effused) fruiting bodies are also considered part of the corticioid fungi. Genera that have hydnoid or odontioid representatives include '' Hydnochaete'', '' Hyphodontia'' and '' Odonticium'' (Hymenochaetales), '' Dentipellis'' (Russulales), '' Dentocorticium'', '' Mycoacia'', '' Radulodon'', '' Steccherinum'' (Polyporales) and '' Sarcodontia''.

Additional hydnoid fungi

Other hydnoid fungi include a group of conspicuous, wood-rotting species with long spines belonging to the genus '' Hericium'' (Russulales), often referred to as "tooth fungi".Pegler DN et al. (1997). ''British chanterelles and tooth fungi''. Kew: Royal Botanic Gardens. . The ear-pick fungus and other species of '' Auriscalpium'' (Russulales) are hydnoid, as is the odd jelly fungus '' Pseudohydnum gelatinosum'' (Auriculariales). The distinction between polypores and hydnoid fungi is not always clear—irregular, split pores can also be interpreted as teeth. Consequently, some species are considered hydnoid or poroid depending on the context (e.g. '' Irpex lacteus''). File:Hydnellum ferrugineum 59267.jpg, The Mealy Tooth, '' Hydnellum ferrugineum'' File:Hydnochaete olivacea.jpg, Dentate hymenophore of ''Hydnochaete olivacea'' File:Irpex lacteus.jpg, Hydnoid-poroid hymenophore of '' Irpex lacteus'' File:Hericium americanum 59265.jpg, The Bear's Head Tooth Fungus, '' Hericium americanum''

References

External links

Scottish stipitate hydnoid brochure

at AmericanMushrooms.com

{{Webarchive, url=https://web.archive.org/web/20081206153305/http://www.treesforlife.org.uk/tfl.tooth_fungi.html , date=2008-12-06 Basidiomycota Mushroom types