Template:Short description Template:Automatic taxobox Template:Mycomorphbox
Armillaria is a genus of fungi that includes the A. mellea species ('honey fungus') that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as A. mellea. Armillaria sp. are long-lived and form the largest living fungi in the world. The largest known specimen (an A. ostoyae) covers more than Template:Convert in Oregon and is estimated to be 2,500 years old. Some species of Armillaria display bioluminescence.
Armillaria can be a destructive forest pathogen. It causes "white rot" root disease. As it feeds on dead plant material, it can kill its host with little negative effect to itself.
TaxonomyEdit
The name Armillaria was defined in 1821 by Elias Magnus Fries, but at that time most gilled mushrooms were considered to belong to genus Agaricus and Armillaria was only a subgenus (a "tribe"). In 1857, Friedrich Staude established the independent genus.<ref name="IF_Armillaria">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Armillaria species morphologically similar to A. mallea were not effectively distinguished until the development of "biological species" defined as intersterile groups by Veikko Hintikka in 1973.<ref name=Hintikka1973>Template:Cite journal</ref> Using a similar technique, Kari Korhonen showed in 1978 that the European Armillaria mellea species complex could be separated into five reproductively isolated species, which he named "European Biological Species" (EBS) A through E.<ref name=Korhonen1978>Template:Cite journal</ref> About the same time, the North American A. mellea was shown to be ten different species (North American Biological Species, or NABS I through X).<ref name=Anderson1979>Template:Cite journal</ref>
| Code | Taxonomic treatment | Compatibility | Known range |
|---|---|---|---|
| EBS A | Armillaria borealis Template:Au<ref>{{#invoke:citation/CS1|citation | CitationClass=web
}}</ref> || || Finland<ref name=Anderson1980>Template:Cite journal</ref> | |
| EBS B | Armillaria cepistipes Template:Au<ref name="Banik">Template:Cite journal</ref> | NABS III (Template:Abbr + Template:Abbr), NABS IV (part) | Finland, Germany<ref name=Anderson1980/> |
| EBS C | Armillaria ostoyae Template:Au | NABS I (part) | Finland<ref name=Anderson1980/> |
| EBS D | Armillaria mellea Template:Au | NABS VIII (part + rg) | Finland<ref name=Anderson1980/> |
| EBS E | Armillaria gallica Template:Au | NABS III (part + rg) | France |
| NABS I | Armillaria ostoyae Template:Au | EBS C (part)<ref name=Anderson1980/> | Vermont,<ref name=Anderson1980/> British Columbia, Prairie Provinces (both boreal and subalpine regions), Ontario, Quebec.<ref name="mall1"/> |
| NABS II | Armillaria gemina Template:Au | Vermont,<ref name=Anderson1980/> Quebec.<ref name="mall1"/> | |
| NABS III | Armillaria calvescens Template:Au | EBS B and E (part + rg)<ref name=Anderson1980/> | Vermont,<ref name=Anderson1980/> Prairie Provinces, Ontario, Quebec.<ref name="mall1"/> |
| NABS IV | EBS B (part),<ref name=Anderson1980/> NABS V (very low?)<ref name="Banik"/> | Vermont<ref name=Anderson1980/> | |
| NABS V | Armillaria sinapina Template:Au | EBS B (5.5%)<ref name="Banik"/> | New York (state),<ref name=Anderson1980/> British Columbia, Prairie Provinces, Ontario, Quebec.<ref name="mall1"/> |
| NABS VI | Armillaria mellea Template:Au<ref name="mall2">Mallett, K. I. (1992). "Armillaria root rot in the Canadian Prairie Provinces". Forestry Canada, Northwest Region, Northern Forestry Centre, Edmonton, Alberta, Information Report NOR-X-329. 22 p.</ref> | EBS D (part)<ref name=Anderson1980/> | Massachusetts,<ref name=Anderson1980/> Quebec.<ref name="mall1"/> |
| NABS VII | Armillaria gallica Template:Au | Vermont, Michigan,<ref name=Anderson1980/> British Columbia<ref name="mall1">Mallett, K. I. (1990). "Armillaria root rot pathogens of the Canadian prairie provinces". Canadian Journal of Forest Research 20:1859–1863.</ref> | |
| NABS VIII | EBS D (part + rg)<ref name=Anderson1980/> | New York, Michigan.<ref name=Anderson1980/> | |
| NABS IX | Armillaria nabsnona Template:Au | Idaho, British Columbia.<ref name=Anderson1980/> | |
| NABS X | Armillaria altimontana Template:Au | NABS V, NABS XI (both <5%)<ref name="Banik"/> | Idaho,<ref name=Anderson1980/> British Columbia.<ref name="mall1"/> |
| NABS XI<ref name="mall2"/> | Armillaria cepistipes Template:Au<ref name="Banik"/> | EBS B (57%)<ref name="Banik"/> | British Columbia<ref name="mall1"/> |
Similar lists of biological species have been constructed by mycologists working in Japan (10 as of 1998)<ref>Template:Cite journal</ref> and China (16 as of 2024).<ref name=Liu24>Template:Cite journal</ref>
Further data from molecular diagnostic tools have removed much uncertainty for mycologists and forest pathologists. New questions remain unanswered regarding the phylogeny of North American Armillaria species and their relationships to their European counterparts, particularly within the "Armillaria mellea complex". Some data suggest that North American and European A. gallica isolates are not monophyletic. Although North American and European isolates of A. gallica may be interfertile, some North American isolates of A. gallica are more closely related to the North American taxon A. calvescens than to European isolates of A. gallica. The increase in genetic divergence has not necessarily barred inter-sterility between isolated populations of A. gallica. Although the relationships among some groups in the genus seem clearer, the investigation of geographically diverse isolates has revealed that the relationship between some North American species is still unclear (Hughes et al. 2003).<ref name="hugh">Hughes, M. B.; Weir, A.; Rogers, S. O. (2003). "Phylogenetic reconstruction of North American Armillaria species and related European taxa based on nuclear ribosomal DNA internal transcribed spacers". p. 32 in Laflamme, G.; Bérubé, J. A.; Bussières, G. (eds.), Root and Butt Rots of Forest Trees. Proceedings of the 10th International Conference of Root and Butt Rots, IUFRO Working Party 7.02.01, Quebec, September 2001. Natural Resources Canada, Canadian Forest Service, Information Report LAU-X-126. 450 p.</ref> A similar situation happens in China, where some molecular phylogenetic data appear to line up with intersterile "biological species" and others do not.<ref name=Liu24/>
Armillaria root rot occurs in the Northwest Territories,Template:Citation needed and was identified on white spruce at Pine Point on Great Slave Lake prior to NABS findings.Template:Citation needed
RhizomorphaEdit
In 1791 Albrecht Wilhelm Roth described the species Rhizomorpha fragilis for a collection which consisted entirely of rhizomorphs. The genus Rhizomorpha thus became established and later these mycelial cords were shown to belong to Armillaria mellea. According to the code of nomenclature that means that the two genus names are synonyms and since genus Armillaria was not defined until 1857, the name Rhizomorpha takes precedence and should replace the name Armillaria. To avoid this, a 2021 paper by Stalpers et al. proposes that the name Armillaria should be protected. The proposal awaits decisions by the Nomenclature Committee for Fungi and eventually by an International Botanical Congress.<ref name="IF_Rhizomorpha">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Koch2018">Template:Cite journal</ref><ref name="Stalpers2021">Template:Cite journal</ref>
DescriptionEdit
The basidiocarp (reproductive structure) of the fungus is a mushroom that grows on wood, typically in small dense clumps or tufts. Their caps (mushroom tops) are typically yellow-brown, somewhat sticky to touch when moist, and, depending on age, may range in shape from conical to convex to depressed in the center. The stipe (stalk) may or may not have a ring. All Armillaria species have a white spore print and none have a volva (cup at base).<ref name=":0">Template:Cite book</ref>
Armillaria species are long-lived and form the largest living fungi in the world.<ref>Template:Cite journal</ref> The largest known organism (of the species A. ostoyae) covers more than Template:Convert in Oregon's Malheur National Forest and is estimated to be 2,500 years old.<ref name="Ingraham2010">Template:Cite book</ref><ref name="si">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Some species display bioluminescence, known as foxfire.
Similar speciesEdit
Similar species include Pholiota spp. which also grow in cespitose (mat-like) clusters on wood and fruit in the fall. Pholiota spp. are separated from Armillaria by its yellowish to greenish-yellow tone and a dark brown to grey-brown spore print. Mushroom hunters need to be wary of Galerina spp. which can grow side by side with Armillaria spp. on wood. Galerina have a dark brown spore print and are deadly poisonous (alpha-amanitin).
The white spore print and lack of volva can be compared to Amanita.<ref name=":0" /> As a white rot, it is distinguished from Tricholoma, a mycorrhizal (non-parasitic) genus.
PathologyEdit
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Honey fungus is a white-rot fungus, which is a pathogenic organism that affects trees, shrubs, woody climbers and rarely, woody herbaceous perennial plants. Honey fungus can grow on living, decaying, and also dead plant material (being a facultative saprophyte). This means it can kill its host with little consequence, unlike parasites that must moderate their growth to avoid host death.Template:R
Honey fungus spreads from living trees, dead and live roots and stumps by means of reddish-brown to black rhizomorphs (root-like structures) at the rate of approximately Template:Convert a year, but infection by root contact is possible. Infection by spores is rare. Rhizomorphs grow close to the soil surface (in the top Template:Convert) and invade new roots, or the root collar (where the roots meet the stem) of plants. An infected tree will die once the fungus has girdled it, or when significant root damage has occurred. Additionally, Infections can occur through the activity of wood boring beetles. For example, Agrilus biguttatus most commonly girdle in oak trees, which allows fungi to grow in the stems of these infected trees. This can happen rapidly, or may take several years. Infected plants will deteriorate, although may exhibit prolific flower or fruit production shortly before death.Template:Why
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Initial symptoms of honey fungus infection include dieback or shortage of leaves in spring. Rhizomorphs (also called mycelial cords) appear under the bark and around the tree, and mushrooms grow in clusters from the infected plant in autumn and die back after the first frost. However these symptoms and signs do not necessarily mean that the pathogenic strains of honey fungus are the cause, so other identification methods are advised before diagnosis. Thin sheets of cream colored mycelium, beneath the bark at the base of the trunk or stem indicated that honey fungus is likely the pathogen. It will give off a strong mushroom scent and the mushrooms sometimes extend upward. On conifers honey fungus often exudes a gum or resin from cracks in the bark.
HostsEdit
Potential hosts include conifers and various monocotyledonous and dicotyledonous trees, shrubs, and herbaceous species, ranging from asparagus and strawberry to large forest trees (Patton and Vasquez Bravo 1967).<ref name="patton">Patton, R. F.; Vasquez Bravo, R. 1967. "Armillaria root rot Armillaria mellea (Vahl ex Fr.) Kummer". p. 37–38 in Davidson, A. G.; Prentice, R. M. (compilers and eds.). Important forest insects and diseases of mutual concern to Canada, the United States, and Mexico. Canadian Department for Rural Development, Ottawa, Ontario, Pub. 1180.</ref> Armillaria root rot enters hosts through the roots. In Alberta, 75% of trap logs (Mallett and Hiratsuka 1985)<ref name="mall3">Template:Cite journal</ref> inserted into the soil between planted spruce became infected with the distinctive white mycelium of Armillaria within one year. Of the infestations, 12% were A. ostoyae, and 88% were A. sinapina (Blenis et al. 1995).<ref name="blen">Blenis, P.; Titus, S.; Mallet, K. 1995. "Impact of Armillaria root rot in intensively managed white spruce/asspen stands". Natural Resources Canada/Alberta Land and Forest Service, Edmonton, Alberta, Canada/Alberta Forest Resource Development Agreement (FRDA), Project A5023-129 Rep. 5 p.</ref> Reviews of the biology, diversity, pathology, and control of Armillaria in Fox (2000)<ref name="fox">Fox, R. T. V. (2000). "Armillaria Root Rot: Biology and Control of Honey Fungus". Intercept, Andover, Hants., England. 222 p.</ref> are useful.
EdibilityEdit
Honey fungus are regarded in Ukraine, Russia, Poland, Germany and other European countries as one of the best wild mushrooms. They are commonly ranked above morels and chanterelles and only the cep/porcini is more highly prized.Template:Citation needed However, honey fungus must be thoroughly cooked as they are mildly poisonous raw. Honey mushrooms are one of four UK species that can cause sickness when ingested with alcohol. For those unfamiliar with the species, it is advisable not to drink alcohol for 12 hours before and 24 hours after eating this mushroom to avoid any possible nausea and vomiting. However, if these rules are followed, this variety of mushroom is a delicacy with a distinctive mushroomy and nutty flavour.Template:Citation needed Reference texts for identification are Collins Complete British Mushrooms and Toadstools for the variety of field pictures in it, and Roger Philips' Mushrooms for the quality of his out of field pictures and descriptions.
In Norway, some mycologists have started to regard honey fungus as poisonous, as the Norwegian health ministry is moving away from the parboiling practice.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite news</ref>
See alsoEdit
ReferencesEdit
External linksEdit
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