Marxm. & Romagn.
Armillaria bulbosa (Barla) Kile & Watling
|gills on hymenium|
|cap is convex|
|hymenium is adnate|
|stipe has a ring|
|spore print is white|
ecology is saprotrophicor parasitic
Armillaria gallica (synonymous with A. bulbosa and A. lutea) is a species of honey mushroom in the Physalacriaceae family of the Agaricales order. The species is a common and ecologically important wood-decay fungus that can live as a saprobe, or as an opportunistic parasite in weakened tree hosts to cause root or butt rot. It is found in temperate regions of Asia, North America, and Europe. The species forms fruit bodies singly or in groups in soil or rotting wood. The fungus has been inadvertently introduced to South Africa. Armillaria gallica has had a confusing taxonomy, due in part to historical difficulties encountered in distinguishing between similar Armillaria species. The fungus received international attention in the early 1990s when an individual colony living in a Michigan forest was reported to cover an area of 15 hectares (37 acres), weigh at least 9,500 kilograms (21,000 lb), and be 1,500 years old. This individual is popularly known as the "humungous fungus", and is a tourist attraction and inspiration for an annual mushroom-themed festival in Crystal Falls.
Armillaria gallica is a largely subterranean fungus, and it produces fruit bodies that are up to about 10 cm (3.9 in) in diameter, yellow-brown, and covered with small scales. On the underside of the caps are gills that are white to creamy or pale orange. The stem may be up to 10 cm (3.9 in) long, with a white cobwebby ring that divides the color of the stem into pale orange to brown above, and lighter-colored below. The fungus can develop an extensive system of underground root-like structures, called rhizomorphs, that help it to efficiently decompose dead wood in temperate broadleaf and mixed forests. It has been the subject of considerable scientific research due to its importance as a plant pathogen, its ability to bioluminesce, its unusual life cycle, and its ability to form large and long-lived colonies.
Phylogeny, taxonomy and naming
|Phylogeny and relationships of A. gallica and related North American species based on amplified fragment length polymorphism data. SY22, ST23, and M70 are A. gallica specimens collected from Michigan, Wisconsin, and British Columbia, respectively.|
Confusion has surrounded the nomenclature and taxonomy of the species now known as Armillaria gallica, paralleling that surrounding the genus Armillaria. The type species, Armillaria mellea, was until the 1970s believed to be a pleiomorphic species with a wide distribution, variable pathogenicity, and one of the broadest host ranges known for the fungi. In 1973, Veikko Hintikka reported a technique to distinguish between Armillaria species by growing them together as single spore isolates on petri dishes and observing changes in the morphology of the cultures. 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. 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); NABS VII was demonstrated shortly after to be the same species as EBS E. Because several research groups had worked with this widely distributed species, it was assigned several different names.
The species that Korhonen called EBS B was named A. bulbosa by Helga Marxmüller in 1982, as it was thought to be equivalent to Armillaria mellea var. bulbosa, first described by Joseph Barla in 1887, and later raised to species status by Josef Velenovský in 1927. In 1973, the French mycologist Henri Romagnesi, unaware of Velenovský's publication, published a description of the species he called Armillariella bulbosa, based on specimens he had found near Compiègne and Saint-Sauveur-le-Vicomte in France. These specimens were later demonstrated to be the same species as the EBS E of Korhonen; EBS B was later determined to be A. cepistipes. Therefore, the name A. bulbosa was a misapplied name for EBS E. In 1987 Romagnesi and Marxmüller renamed EBS E to Armillaria gallica. Another synonym, A. lutea, had originally been described by Claude Casimir Gillet in 1874, and proposed as a name for EBS E. Although the name had priority due to its early publication date, it was rejected as a nomen ambiguum because of a lack of supporting evidence to identify the fungus, including a specimen, type locality, and incomplete collection notes.A. inflata (Velenovský, 1920) may represent another synonym, but the type specimens were not preserved, so it is considered a dubious name (nomen dubium). As of 2010, both the Index Fungorum and MycoBank consider Armillaria gallica Marxm. & Romagn. to be the current name, with A. bulbosa and A. lutea as synonyms.
Phylogenetic analysis of North American Armillaria species based on analysis of amplified fragment length polymorphism data suggests that A. gallica is most closely related to A. sinapina, A. cepistipes, and A. calvescens. These results are similar to those reported in 1992 that compared sequences of nuclear ribosomal DNA.
The specific epithet gallica is botanical Latin for "French" (from Gallia, "Gaul"), and refers to the type locality. The prior name bulbosa is Latin for "bulb-bearing, bulbous" (from bulbus and the suffix -osa).Armillaria is derived from the Latin armilla, or "bracelet".
The fruit bodies of Armillaria gallica have caps that are 2.5–9.5 cm (1.0–3.7 in) broad, and depending on their age, may range in shape from conical to convex to flattened. The caps are brownish-yellow to brown when moist, often with a darker-colored center; the color tends to fade upon drying. The cap surface is covered with slender fibers (same color as the cap) that are erect, or sloping upwards.
When the fruit bodies are young, the underside of the caps have a cottony layer of tissue stretching from the edge of the cap to the stem—a partial veil—which serves to protect the developing gills. As the cap grows in size the membrane is eventually pulled away from the cap to expose the gills. The gills have an adnate (squarely attached) to somewhat decurrent (extending down the length of the stem) attachment to the stem. They are initially white, but age to a creamy or pale orange covered with rust-colored spots. The stem is 4–10 cm (1.6–3.9 in) long and 0.6–1.8 cm (0.24–0.71 in) thick, and almost club-shaped with the base up to 1.3–2.7 cm (0.5–1.1 in) thick. Above the level of the ring, the stem is pale orange to brown, while below it is whitish or pale pink, becoming grayish-brown at the base. The ring is positioned about 0.4–0.9 cm (0.16–0.35 in) below the level of the cap, and may be covered with yellowish to pale-brownish woolly cottony mycelia. The base of the stem is attached to rhizomorphs, black root-like structures 1–3 mm in diameter. While the primary function of the below-ground mycelia is to absorb nutrients from the soil, the rhizomorphs serve a more exploratory function, to locate new food bases.
When the spores are seen in deposit, such as with a spore print, they appear whitish. They have an ellipsoid or oblong shape, usually contain an oil droplet, and have dimensions of 7–8.5 by 5–6 µm. The spore-bearing cells, the basidia, are club-shaped, four-spored (rarely two-spored), and measure 32–43 by 7–8.7 µm. Other cells present in the fertile hymenium include the cheilocystidia (cystidia present on the edge of a gill), which are club-shaped, roughly cylindrical and 15–25 by 5.0–12 µm. Cystidia are also present on the stem (called caulocystidia), and are broadly club-shaped, measuring 20–55 by 11–23 µm. The cap cuticle is made of hyphae that are irregularly interwoven and project upward to form the scales seen on the surface. The hyphae that make up the surface scales typically measure 26–88 µm long by 11–27 µm thick and can be covered with a crust of pigment. Clamp connections are present in the hyphae of most tissues.
Like all Armillaria species, A. gallica is considered edible. Thorough cooking is usually recommended, as the raw mushroom tastes acrid when fresh or undercooked. One author advises to consume only a small portion initially, as some people may experience an upset stomach. The taste is described as "mild to bitter", and the odor "sweet", or reminiscent of camembert cheese.
Armillaria calvescens is rather similar in appearance, and can only be reliably distinguished from A. gallica by observing microscopic characteristics. A. calvescens has a more northern distribution, and in North America, is rarely found south of the Great Lakes.A. mellea has a thinner stem than A. gallica, but can be more definitively distinguished by the absence of clamps at the base of the basidia. Similarly, A. cepistipes and A. gallica are virtually identical in appearance (especially older fruit bodies), and are identified by differences in geographical distribution, host range, and microscopic characteristics. Molecular methods have been developed to discriminate between the two species by comparing DNA sequences in the gene coding translation elongation factor 1-alpha.
Armillaria gallica can produce cyclobutane-containing metabolites such as arnamiol, a natural product that is classified as a sesquiterpenoid aryl ester. Although the specific function of arnamiol is not definitively known, similar chemicals present in other Armillaria species are thought to play a role in inhibiting the growth of antagonistic bacteria or fungi, or in killing cells of the host plant prior to infection.
The mycelia (but not the fruit bodies) of Armillaria gallica are known to be bioluminescent. Experiments have shown that the intensity of the luminescence is enhanced when the mycelia are disturbed during growth or when they are exposed to fluorescent light. Bioluminescence is caused by the action of luciferases, enzymes that produce light by the oxidation of a luciferin (a pigment). The biological purpose of bioluminescence in fungi is not definitively known, although several hypotheses have been suggested: it may help attract insects to help with spore dispersal, it may be a by-product of other biochemical functions, or it may help deter heterotrophs that might consume the fungus.
Researchers reported finding Armillaria gallica in the Upper Peninsula of Michigan in the early 1990s, during an unrelated research project to study the possible biological effects of extremely low frequency radio stations, which were being investigated as a means to communicate with submerged submarines. In one particular forest stand, Armillaria-infected oak trees had been harvested, and their stumps were left to rot in the field. Later, when red pines were planted in the same location, the seedlings were killed by the fungus, identified as A. gallica (then known as A. bulbosa). Using molecular genetics, they determined that the underground mycelia of one individual fungal colony covered 15 ha (37 acres), weighing over 9,500 kilograms (21,000 lb), with an estimated age of 1,500 years. The analysis used restriction fragment length polymorphism (RFLP) and random amplification of polymorphic DNA (RAPD) to examine isolates collected from fruit bodies and rhizomorphs (underground aggregations of fungal cells that resemble plant roots) along 1-kilometer (0.6 mi) transects in the forest. The 15-hectare area yielded isolates that had identical mating type alleles and mitochondrial DNA restriction fragment patterns; this degree of genetic similarity indicated that the samples were all derived from a single genetic individual, or clone, that had reached its size through vegetative growth. In their conclusion the authors noted: "This is the first report estimating the minimum size, mass, and age of an unambiguously defined fungal individual. Although the number of observations for plants and animals is much greater, members of the fungal kingdom should now be recognized as among the oldest and largest organisms on earth." After the Nature paper was published, major media outlets from around the world visited the site where the specimens were found; as a result of this publicity, the individual acquired the common name "humongous fungus". There was afterward some scholarly debate as to whether the fungus qualified to be considered in the same category as other large organisms such as the blue whale or the giant redwood.
The fungus has since become a popular tourist attraction in Michigan, and has inspired a "Humongous Fungus Fest" held annually in August in Crystal Falls. The organism was the subject of a Late Show Top Ten List on Late Night with David Letterman, and an advertising campaign by the rental company U-Haul.
Life cycle and growth
The life cycle of A. gallica includes two diploidization–haploidization events. The first of these is the usual process of cell fusion (forming a diploid) followed by meiosis during the formation of haploid basidiospores. The second event is more cryptic, and occurs before fruit body formation. In most basidiomycetous fungi, the hyphae of compatible mating types will fuse to form a two-nucleate, or dikaryotic stage; this stage is not observed in Armillaria species, which have cells that are mostly monokaryotic and diploid. Genetic analyses suggest that the dikaryotic mycelia undergo an extra haploidization event prior to fruit body formation to create a genetic mosaic. These regular and repeating haploidization events result in increased genetic diversity, which helps the fungus to adapt to unfavorable changes in environmental conditions, like drought.
The growth rate of A. gallica rhizomorphs is between 0.3 and 0.6 m (1.0 and 2.0 ft) per year.Population genetic studies of the fungus conducted in the 1990s demonstrated that genetic individuals grow mitotically from a single point of origin to eventually occupy territories that may include many adjacent root systems over large areas (several hectares) of forest floor. Based on the low mutation rates observed in large, long-lived individuals, A. gallica appears to have an especially stable genome. It has also been hypothesized that genetic stability may result from self-renewing mycelial repositories of nuclei with stem cell-like properties.
Habitat and distribution
Armillaria gallica can normally be found on the ground, but sometimes on stumps and logs. Mushrooms that appear to be terrestrial are attached to plant roots underneath the surface. It is widely distributed and has been collected in North America, Europe, and Asia (China, Iran, and Japan). The species has also been found in the Western Cape Province of South Africa, where it is thought to have been introduced from potted plants imported from Europe during the early colonization of Cape Town. In Scandinavia, it is absent in areas with very cold climates, like Finland or Norway, but it is found in southern Sweden. It is thought to be the most prevalent low altitude species of Armillaria in Great Britain and France. The upper limits of its altitude vary by region. In the French Massif Central, it is found up to 1,100 m (3,600 ft), while in Bavaria, which has a more continental climate, the upper limit of distribution reaches 600 m (2,000 ft). In Serbian forests, it is the most common Armillaria between elevations of 70 to 1,450 m (230 to 4,760 ft).Field studies suggest that A. gallica prefers sites that are low in organic matter and have high soil pHs.
In North America, it is common east of the Rocky Mountains, but rare in the Pacific Northwest. In California, where it is widely distributed, the fungus is found in a variety of plant communities, including aspen, coastal oak woodland, Douglas Fir, Klamath mixed conifer, montane hardwood, montane hardwood-conifer, montane riparian, Redwood, Sierran mixed conifer, valley oak woodland, valley-foothill riparian, and White Fir. It was found to be the most common Armillaria species in hardwood and mixed oak forests in western Massachusetts.
A Chinese study published in 2001 used the molecular biological technique restriction fragment length polymorphism to analyze the differences in DNA sequence between 23 A. gallica specimens collected from the Northern Hemisphere. The results suggest that based on the restriction fragment length polymorphism patterns observed, there are four global A. gallica subpopulations: the Chinese, European, North American–Chinese, and North American–European geographical lineages. A 2007 study on the northeastern and southwestern Chinese distribution of Armillaria, using fruit body and pure culture morphology, concluded that there are several unnamed species (Chinese biological species C, F, H, J and L) that are similar to the common A. gallica.
Armillaria gallica is a weaker pathogen than the related A. Mellea or A. Solidipes, and is considered a secondary parasite—typically initiating infection only after the host's defenses have been weakened by insect defoliation, drought, or infection by another fungus. Fungal infection can lead to root rot or butt rot. As the diseased trees die, the wood dries, increasing the chance of catching fire after being struck by lightning. The resulting forest fire may in turn kill the species that killed the trees. Plants that are under water stress caused by dry soils or waterlogging are more susceptible to infection by A. gallica. It has been shown to be one of several Armillaria species responsible for widespread mortality of oak trees in the Arkansas Ozarks. The fungus has also been shown to infect Daylily in South Carolina,Northern highbush blueberry (Vaccinium corymbosum) in Italy and vineyards (Vitis species) of Rías Baixas in northwestern Spain. The latter infestation "may be related to the fact that the vineyards from which they were isolated were located on cleared forestry sites". When A. solidipes and A. gallica co-occur in the same forest, infection of root systems by A. gallica may reduce damage or prevent infection from A. solidipes.
Armillaria gallica can develop an extensive subterranean system of rhizomorphs, which helps it to compete with other fungi for resources or to attack trees weakened by other fungi. A field study in an ancient broadleaved woodland in England showed that of five Armillaria species present in the woods, A. gallica was consistently the first to colonize tree stumps that had been coppiced the previous year.Fractal geometry has been used to model the branching patterns of the hyphae of various Armillaria species. Compared to a strongly pathogenic species like A. solidipes, A. gallica has a relatively sparse branching pattern that is thought to be "consistent with a foraging strategy in which acceptable food bases may be encountered at any distance, and which favours broad and divisive distribution of potential inoculum." Because the rhizomorphs form regular networks, mathematical concepts of graph theory have been employed to describe fungal growth and interpret ecological strategies, suggesting that the specific patterns of network attachments allow the fungus "to respond opportunistically to spatially and temporally changing environments".
Armillaria gallica may itself be parasitized by other soil flora. Several species of the fungus Trichoderma, including Trichoderma polysporum, T. harzianum and T. viride, are able to attack and penetrate and the outer tissue of A. gallica rhizomorphs and parasitize the internal hyphae. The infected rhizomorphs become devoid of living hyphae about one week after the initial infection.Entoloma abortivum is another fungus that can live parasitically upon A. gallica. The whitish-gray malformed fruit bodies that may result are due to the E. abortivum hyphae penetrating the mushroom and disrupting its normal development.
- Kim, M-S, Klopfenstein NB, Hanna JW, McDonald GI. (2006). "Characterization of North American Armillaria species: genetic relationships determined by ribosomal DNA sequences and AFLP markers" (PDF). Forest Pathology 36 (3): 145–64. doi:10.1111/j.1439-0329.2006.00441.x.
- Termorshuizen AJ, Arnolds EJM. (1997). "Compatibility groups, species concepts and nomenclature in European Armillaria species". Mycotaxon 65: 263–72. Retrieved 2010-02-19.
- Volk TJ, Burdsall HH Jr. (1995). A Nomenclatural Study of Armillaria and Armillariella species (Basidiomycotina, Tricholomataceae). Oslo, Norway: Fungiflora. p. 13.
- Hintikka V. (1973). "A note on the polarity of Armillaria mellea". Karstenia 13: 32–39.
- Korhonen K. (1978). "Interfertility and clonal size in the Armillaria mellea complex". Karstenia 18: 31–42.
- Anderson JB, Ullrich RC. (1979). "Biological species of Armillaria in North America". Mycologia 71 (2): 401–14. JSTOR 3759160.
- Anderson JB, Korhonen K, Ullrich RC. (1980). "Relationships between European and North American biological species of Armillaria mellea". Experimental Mycology 4 (1): 78–86. doi:10.1016/0147-5975(80)90053-5.
- Marxmüller H. (1982). "Étude morphologique des Armillaria ss. str. à anneau" [Morphological study of Armillaria sensu stricto with rings]. Bulletin de la Société Mycologique de France (in French) 98: 87–124.
- Barla J. (1887). "Champignons des Alpes-Maritimes" [Mushrooms of the Alpes-Maritimes]. Bulletin de la Société Mycologique de France (in French) 3: 142–43.
- Velenovský J. (1927). "Václavka hlíznatá (Armillaria bulbosa Barla)". Mykologia (Praha) (in Czech) 4: 116–17.
- Marxmüller H. (1992). "Some notes on the taxonomy and nomenclature of five European Armillaria species". Mycotaxon 44 (2): 267–74.
- Marxmüller H. (1987). "Quelques remarques complémentaires sur les Armillaires annelées" [Some complementary remarks on ringed Armillarias]. Bulletin de la Société Mycologique de France (in French) 103: 137–56.
- Gillet CC. (1874). Les Hyménomycètes ou Description de tous les Champignons qui Croissent en France [The hymenomycetes or description of all the mushrooms that grow in France] (in French). France: Alençon. pp. 1–176.
- Watling R. (1987). "The occurrence of annulate Armillaria species in northern Britain". Notes from the Royal Botanical Garden, Edinburgh 44: 459–84.
- Termorshuizen A, Arnolds E. (1987). "On the nomenclature of the European species of the Armillaria mellea group". Mycotaxon 30 (4): 101–16. Retrieved 2010-03-18.
- Antonín V. (1990). "Studies in annulate species of the genus Armillaria–III. Species described by Josef Velenovský". Acta Musei Moraviae: Scientiae Naturales 75: 129–32.
- "Species synonymy for Armillaria gallica". Index Fungorum. CAB International. Retrieved 2010-02-16.
- "Armillaria gallica". MycoBank. International Mycological Association. Retrieved 2010-02-16.
- Anderson JB, Stasovski E. (1992). "Molecular phylogeny of northern hemisphere species of Armillaria". Mycologia 84 (4): 505–16. doi:10.2307/3760315. JSTOR 3760315.
- P.G.W. Glare, ed. (1982) . Oxford Latin Dictionary (combined ed.). Oxford, UK: Clarendon Press. ISBN 0-19-864224-5. ss. vv. "Gallia", p. 753; "bulbosus", p. 244.
- Stearn WT (1973). Botanical Latin (2nd annot. and rev. ed.). Newton Abbot: David & Charles. pp. 221, 396.
- Stager C. (1999). Field Notes from the Northern Forest. Syracuse, New York: Syracuse University Press. p. 219. ISBN 0-8156-0572-2.
- Fox RTV (2000). "Biology and life cycle". In Fox RTV. Armillaria Root Rot: Biology and Control of Honey Fungus. Andover, Hampshire, UK: Intercept. pp. 5–9. ISBN 1-898298-64-5.
- Mihail JD, Obert M, Bruhn JN, Taylor SJ. (1995). "Fractal geometry of diffuse mycelia and rhizomorphs of Armillaria species". Mycological Research 99 (1): 81–88. doi:10.1016/S0953-7562(09)80320-1.
- Bas C, Kuyper Th W, Noordeloos ME, Vellinga EC, van Os J. (1995). Flora Agaricina Neerlandica 3. Boca Raton, Florida: CRC Press. pp. 37–38. ISBN 90-5410-616-6.
- Antonín V, Tomšovský M, Sedlák P, Májek T, Jankovský L. (2009). "Morphological and molecular characterization of the Armillaria cepistipes – A. gallica complex in the Czech Republic and Slovakia". Mycological Progress 8 (3): 259–71. doi:10.1007/s11557-009-0597-1.
- Phillips R. "Rogers Mushrooms | Mushroom Pictures & Mushroom Reference". Rogers Mushrooms. Retrieved 2010-02-16.
- Kuo M. (October 2004). "Armillaria gallica". MushroomExpert.Com. Archived from the original on 4 January 2010. Retrieved 2010-02-18.
- "The Honey Fungus Armillaria mellea/gallica". Northern Ireland Fungus Group. Archived from the original on 12 January 2010. Retrieved 2010-02-18.
- Gribble WG. (2009). Naturally Occurring Organohalogen Compounds – A Comprehensive Update. Springer. p. 324. ISBN 978-3-211-99322-4.
- Dervilla MX, Coveney DJ, Fukuda N. (1986). "New sesquiterpene aryl esters from Armillaria mellea". Journal of Natural Products 49 (1): 111–16. doi:10.1021/np50043a013.
- Peipp H, Sonnenbichler J. (1992). "Secondary fungal metabolites and their biological-activities, II. Occurrence of antibiotic compounds in cultures of Armillaria ostoyae growing in the presence of an antagonistic fungus or host plant-cells". Biological Chemistry Hoppe-Seyler 373 (8): 675–83. doi:10.1515/bchm3.1992.373.2.675. PMID 1418682.
- Gao LW, Wan YL, Zhao YL, Wang JW. (2009). "The cultivation, bioactive components and pharmacological effects of Armillaria mellea" (PDF). African Journal of Biotechnology 8 (25): 7383–90.
- Mihail JD, Bruhn JN. (2007). "Dynamics of bioluminescence by Armillaria gallica, A. mellea and A. tabescens" (PDF). Mycologia 99 (3): 341–50. doi:10.3852/mycologia.99.3.341. PMID 17883025.
- Shimomura O. (2006). Bioluminescence: Chemical Principles and Methods. Singapore: World Scientific. pp. 268–75. ISBN 981-256-801-8.
- Sivinski J. (1981). "Arthropods attracted to luminous fungi". Psyche 88 (3–4): 383–90. doi:10.1155/1981/79890.
- Buller AHR. (1924). "The bioluminescence of Panus stypticus". Researches on Fungi III. London, UK: Longsman, Green and Co. pp. 357–431.
- Stamets P. (2000). Growing Gourmet and Medicinal Mushrooms. Berkeley, California: Ten Speed Press. p. 9. ISBN 978-1-58008-175-7.
- Volk TJ. (2002-04). "The Humongous Fungus – Ten Years Later". Department of Biology, University of Wisconsin. Retrieved 2010-02-16.
- Smith ML, Bruhn JM, Anderson JB. (1992). "The fungus Armillaria bulbosa is among the largest and oldest living organisms". Nature 356 (6368): 428–31. doi:10.1038/356428a0.
- Wilson J. (1999). Biological Individuality: the Identity and Persistence of Living Entities. Cambridge, UK: Cambridge University Press. pp. 23–25. ISBN 0-521-62425-8.
- Sceurman M, Godfrey LS, Moran MM. (2006). Weird Michigan. New York, New York: Sterling. p. 41. ISBN 1-4027-3907-9.
- Sieger J, Feldman MB. (2004). Something I Said?: Innuendo and Out the Other. Madison: University of Wisconsin Press, Terrace Books. p. 160. ISBN 0-299-20270-4.
- Peabody DC, Peabody RB. (1985). "Widespread haploidy in monokaryotic cells of mature basidiocarps of Armillaria bulbosa, a member of the Armillaria mellea complex". Experimental Mycology 9: 212–20.
- Peabody RB, Peabody DC, Sicard KM. (2000). "A genetic mosaic in the fruiting stage of Armillaria gallica". Fungal genetics and Biology 29 (2): 72–80. doi:10.1006/fgbi.2000.1187. PMID 10919376.
- Peabody DC, Peabody RB, Tyrrell MG, Towle MJ, Johnson EM. (2003). "Phenotypic plasticity and evolutionary potential in somatic cells of Armillaria gallica". Mycological Research 107 (Pt 4): 408–12. doi:10.1017/S0953756203007433. PMID 12825512.
- Peabody RB, Peabody DC, Tyrrell MG, Edenburn-McQueen E, Howdy RP, Semelrath KM. (2005). "Haploid vegetative mycelia of Armillaria gallica show among-cell-line variation for growth and phenotypic plasticity". Mycologia 97 (4): 777–87. doi:10.3852/mycologia.97.4.777. PMID 16457347.
- Gatto A, Sicoli G, Luisi N. (2009). "Genetic diversity within an Italian population of forest Armillaria gallica isolates as assessed by RAPD-PCR analysis". Journal of Phytopathology 157 (2): 94–100. doi:10.1111/j.1439-0434.2008.01456.x.
- Rishbeth J. (1991). "Armillaria in an ancient broadleaved woodland". European Journal of Forest Pathology 21 (4): 239–49. doi:10.1111/j.1439-0329.1991.tb00975.x.
- Rizzo DM, Blanchette RA, May G. (1995). "Distribution of Armillaria ostoyae genets in a Pinus resinosa-Pinus banksiana forest". Canadian Journal of Botany 73 (5): 776–87. doi:10.1139/b95-085.
- Saville BJ, Yoell H, Anderson JB. (1996). "Genetic exchange and recombination in populations of the root-infecting fungus Armillaria gallica". Molecular Evolution 5 (4): 485–97. PMID 8794559.
- Hodnett B, Anderson JB. (2000). "Genomic stability of two individuals of Armillaria gallica". Mycologia 92 (5): 894–99. doi:10.2307/3761585. JSTOR 3761585.
- Gladfelter A, Berman J. (2009). "Dancing genomes: fungal nuclear positioning". Nature Reviews. Microbiology 7 (12): 875–86. doi:10.1038/nrmicro2249. PMC 2794368. PMID 19898490.
- Roody WC. (2003). Mushrooms of West Virginia and the Central Appalachians. University Press of Kentucky. p. 31. ISBN 978-0-8131-9039-6.
- Qin GF, Zhao J, Korhonen K. (2007). "A study on intersterility groups of Armillaria in China". Mycologia 99 (3): 430–41. doi:10.3852/mycologia.99.3.430. PMID 17883035.
- Asef MR, Goltapeh EM, Alizadeh A. (2003). "Identification of Armillaria biological species in Iran" (PDF). Fungal Diversity 14: 51–60.
- Ota Y, Sotome K, Hasegawa E. (2009). "Seven Armillaria species identified from Hokkaido Island, northern Japan". Mycoscience 50 (6): 442–47. doi:10.1007/s10267-009-0505-1.
- Coetzee MPA, Wingfield BD, Roux J, Crous PW, Denman S, Wingfield MJ. (2003). "Discovery of two northern hemisphere Armillaria species on Proteaceae in South Africa" (PDF). Plant Pathology 52 (5): 604–12. doi:10.1046/j.1365-3059.2003.00879.x.
- Guillaumin J-J, Mohammed C, Anselmi R, Courtecuisse R, Gregory SC, Holdenrieder O, Intini M, Lung B, Marxmüller H, Morrison D, Rishbeth J, Termorshuizen AJ, Tirró A, Van Dam B. (1993). "Geographical distribution and ecology of the Armillaria species in western Europe". European Journal of Forest Pathology 23 (3): 321–41. doi:10.1111/j.1439-0329.1994.tb00978.x.
- Keča N, Karadžić D, Woodward S. (2009). "Ecology of Armillaria species in managed forests and plantations in Serbia". Forest Pathology 39 (4): 217–31. doi:10.1111/j.1439-0329.2008.00578.x.
- Blodgett JT, Worrall JJ. (1992). "Site relationships of Armillaria species in New York" (PDF). Plant Disease 76 (2): 170–74. doi:10.1094/PD-76-0170.
- Oliva J, Suz LM, Colinas C. (2009). "Ecology of Armillaria species on silver fir (Abies alba) in the Spanish Pyrenees". Annals of Forest Science 66 (6): 603–13. doi:10.1051/forest/2009046.
- Ammirati J, Trudell S. (2009). Mushrooms of the Pacific Northwest: Timber Press Field Guide (Timber Press Field Guides). Portland, Oregon: Timber Press. p. 109. ISBN 0-88192-935-2.
- Baumgartner K, Rizzo DM. (2001). "Distribution of Armillaria species in California". Mycologia 93 (5): 821–30. doi:10.2307/3761748. JSTOR 3761748.
- Brazee NJ, Wick RL. (2009). "Armillaria species distribution on symptomatic hosts in northern hardwood and mixed oak forests in western Massachusetts". Forest Ecology and Management 258 (7): 1605–12. doi:10.1016/j.foreco.2009.07.016.
- Qin GuoFu, Zhao Jun, Tian ShuMin, Hantula J. (2001). "Genetic diversity and molecular identification of Northern Hemisphere species of Armillaria gallica". Scientia Silvae Sinicae (in Chinese) 37 (2): 61–68.
- Marçais B, Bréda N. (2006). "Role of an opportunistic pathogen in the decline of stressed oak trees". Journal of Ecology 94 (6): 1214–23. doi:10.1111/j.1365-2745.2006.01173.x.
- Healy RA, Huffman DR., Tiffany LH, Knaphaus G. (2008). Mushrooms and Other Fungi of the Midcontinental United States (Bur Oak Guide). Iowa City, Iowa: University of Iowa Press. p. 127. ISBN 1-58729-627-6.
- Stamets P. (2005). Mycelium Running: How Mushrooms Can Help Save the World. Berkeley, California: Ten Speed Press. p. 43. ISBN 978-1-58008-579-3.
- Packham JR, Thomas PDG. (2007). Ecology of Woodlands and Forests: Description, Dynamics and Diversity. Cambridge, UK: Cambridge University Press. p. 205. ISBN 0-521-83452-X.
- Kelley MB, Fierke MK, Stephen FM. (2009). "Identification and distribution of Armillaria species associated with an oak decline event in the Arkansas Ozarks". Forest Pathology 39 (6): 397–404. doi:10.1111/j.1439-0329.2009.00600.x.
- Schnabel G, Bussey KE, Bryson PK. (2005). "First report of Armillaria gallica causing Armillaria root rot in Daylily in South Carolina". Plant Disease 89 (6): 683. doi:10.1094/PD-89-0683A.
- Prodorutti D, Palmieri L, Gobbin D, Pertot I. (2006). "First report of Armillaria gallica on highbush blueberry (Vaccinium corymbosum) in Italy". Plant Pathology 55 (4): 583. doi:10.1111/j.1365-3059.2006.01420.x.
- Prodorutti D, Vanblaere T, Gobbin D, Pellegrini A, Gessler C, Pertot I. (2009). "Genetic diversity of Armillaria spp. infecting highbush blueberry in Northern Italy (Trentino region)". Phytopathology 99 (6): 651–58. doi:10.1094/PHYTO-99-6-0651. PMID 19453223.
- Aguín-Casal O, Sáinz-Osés MJ, Mansilla-Vázquez JP. (2003). "Armillaria species infesting vineyards in northwestern Spain". European Journal of Plant Pathology 110 (7): 683–87. doi:10.1023/B:EJPP.0000041553.98879.51.
- "Armillaria gallica". Insects and Diseases of Canadian Forests. Canadian Forest Service. Retrieved 2010-02-18.[dead link]
- Lamour A, Termorshuizen AJ, Volker D, Jeger MJ. (2007). "Network formation by rhizomorphs of Armillaria lutea in natural soil: their description and ecological significance". FEMS Microbiology Ecology 62 (2): 222–32. doi:10.1111/j.1574-6941.2007.00358.x. PMID 17645531.
- Dumas MT, Boyonoski NW. (1992). "Scanning electron microscopy of mycoparasitism of Armillaria rhizomorphs by species of Trichoderma". European Journal of Forest Pathology 22 (6–7): 379–83. doi:10.1111/j.1439-0329.1992.tb00310.x.
- Czederpiltz DL, Volk TJ, Burdsall HH Jr. (2001). "Field observations and inoculation experiments to determine the nature of the carpophoroids associated with Entoloma abortivum and Armillaria". Mycologia 93 (5): 841–51. doi:10.2307/3761750. JSTOR 3761750.