The hydnoid 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, Ba ...

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 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 plants, algae ...

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

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial no ...

'' Hydnum'' ("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 his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...

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 genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as w ...

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

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

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

type species In 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 species that contains the biological type specimen( ...

, '' Hydnum repandum'', and its relatives in the order

Cantharellales The Cantharellales are an order of fungi in the class Agaricomycetes. The order includes not only the chanterelles (Cantharellaceae), but also some of the tooth fungi (Hydnaceae), clavarioid fungi ( Aphelariaceae and Clavulinaceae), and cort ...

. Other species originally described in ''Hydnum'' have been reassigned to various genera in various orders including the

Agaricales The fungal order Agaricales, also known as gilled mushrooms (for their distinctive gills) or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13,000 described species, ...

, Auriculariales,

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 Ramariaceae ...

, Hymenochaetales,

Polyporales The Polyporales are an order of about 1800 species of fungi in the division Basidiomycota. The order includes some (but not all) polypores as well as many corticioid fungi and a few agarics (mainly in the genus '' Lentinus''). Many species wit ...

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 consi ...

, Thelephorales and

Trechisporales The Hydnodontaceae are a family of fungi in the class Agaricomycetes. According to a 2008 estimate, the family contains 15 genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms ...

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 ''Sarcodon'' is a genus of fungi in the family Bankeraceae, which is part of the order Thelephorales known for its almost universal ectomycorrhizal life style. The genus owes its name to the presence of teeth-like spines on the hymenophore, it ...

''. All are

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 mycob ...

, belong in the Thelephorales, 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 '' Hydnum'' and the related ''Sistotrema confluens'' (

) are also mycorrhizal, but have different ecological requirements. Other stipitate hydnoid fungi are wood decomposing, such as some species of '' Beenakia'' (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 Jelly fungi are a paraphyletic group of several heterobasidiomycete fungal orders from different classes of the subphylum Agaricomycotina: Tremellales, Dacrymycetales, Auriculariales and Sebacinales. These fungi are so named because their ...

Pseudohydnum gelatinosum ''Pseudohydnum gelatinosum'' is a species of fungus in the order Auriculariales. It has the recommended English name English names are names used in, or originating in, England. In England as elsewhere in the English-speaking world, a comp ...

'' (Auriculariales). The distinction between

polypore Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside (see Delimitation for exceptions). They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all pol ...

s 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

{{reflist

External links

Scottish stipitate hydnoid brochure

at AmericanMushrooms.com

Basidiomycota Mushroom types