Armillaria ''Armillaria'' is a genus of fungi that includes the ''Armillaria mellea, A. mellea'' species known as honey fungi that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as ''A. mellea''. ''Armill ...

'' is a

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 nom ...

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 ...

commonly known as honey mushrooms. First treated by Elias Magnus Fries in 1821, and later assigned generic rank by Friedrich Staude in 1857, ''Armillaria'' is classified in the family

Physalacriaceae The Physalacriaceae are a family of fungi in the order Agaricales. Species in the family have a widespread distribution, ranging from the Arctic, ('' Rhizomarasmius''), to the tropics, e.g. '' Gloiocephala'', and from marine sites ('' Mycaureola ...

of the Agaricales, the gilled mushrooms. The majority of

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in ''Armillaria'' are

saprotrophic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ( ...

and live mainly on dead wood, but some are

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

that can cause

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the su ...

and

butt rot Butt rot is a disease of plants, mostly trees, caused by fungi. The fungus attacks the moist, poorly protected undersurface of tree trunk's thickest part (the "butt" above the root, as opposed to "top"), where the end of the stem makes contact wi ...

in over 600 species of woody plants. Some ''Armillaria'' species form mycorrhizae with orchids; others, such as '' A. gallica'', '' A. mellea'', and '' A. tabescens'', are bioluminescent. ''Armillaria'' species form fleshy, white- spored mushrooms with a cottony or membranous

veil A veil is an article of clothing or hanging cloth that is intended to cover some part of the head or face, or an object of some significance. Veiling has a long history in European, Asian, and African societies. The practice has been prominent ...

that typically forms a distinct annulus on the stem. The

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

usually occur in autumn in large clusters at the base of the stem or roots. ''Armillaria'' species can produce rhizomorphs—rootlike aggregations of hyphae—that can form massive, long-lasting underground networks. The growth of the rhizomorph networks allows for tree-to-tree spread of the fungus even when direct contact between diseased and healthy plants is not possible. The genus once served as a

wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined ...

for many

agaric An agaric () is a type of fungus fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. In the UK, agarics are called "mushroom ...

mushrooms with a white

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

, gills attached to the stem, and an annulus. Due largely to differing interpretations on the limits of the genus, over 270 species and

varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

have been placed in ''Armillaria'' or its synonym ''Armillariella''. A comprehensive 1995 study by Tom Volk and Harold Burdsall evaluated all of the epithets that have been used in ''Armillaria'' or ''Armillariella''. They determined that about 40 species belong to ''Armillaria'' '' sensu stricto'' (in the strict sense); the remaining names belong to species that are distributed among 43 other modern fungal genera. Many species are difficult or impossible to distinguish from each other using observable characteristics; laboratory incompatibility tests are often used on

pure culture A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagn ...

s to reliably determine species. Because of the difficulties posed by routine species identification, the use of DNA sequencing and

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

approaches has become a standard method to help clarify relationships between species. Species differ in their geographical distribution and ecological position,

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

specificity, microscopic and macroscopic features, and also in their aggressiveness in colonizing wood hosts. The following list of ''Armillaria'' species is based on the taxonomic overviews provided by Volk and Burdsall in 1995,Volk and Burdsall (1995).

David Pegler David Norman Pegler (born 2 November 1938) is a British mycologist. Until his retirement in 1998, he served as the Head of Mycology and assistant keeper of the herbarium at the Royal Botanic Gardens in Kew. Pegler received his BSc from London Un ...

in 2000, and reports of new species that have been published since then.

Species

;Key to the table of species below: Armillaria borealis - Lindsey

Species

Notes

References

Cited literature