| Rhizomorpha | |
|---|---|
 | |
| R. corynephora (= Brunneocorticium corynecarpon) | |
| Scientific classification | |
| Kingdom: | |
| Division: | |
| Class: | |
| Order: | |
| Family: | |
| Genus: | Rhizomorpha Roth (1791) |
Rhizomorpha is a genus of fungi that was created for species known only by their mycelial cords ("rhizomorphs") and so impossible to classify within the normal taxonomic system, which is based on reproductive structures.
Mycelial cords, or rhizomorphs, are long strands sent out by some fungi to colonize new space and absorb nutrients. They typically run along the ground or under bark, but may also hang in the air. They are complex structures, big enough to be seen with the naked eye, and they should not be confused with the microscopic thread-like cells (hyphae) of which they are composed. Fungi are generally classified according to their sexual or asexual spore-bearing organs (including fruiting bodies where present), but where only sterile rhizomorphs were available, such species were put into genus Rhizomorpha even if they were not genetically related. [1] [2]
The genus was created in 1791 by Albrecht Wilhelm Roth for an observation of material in the form of mycelial cords, which he assigned to species Rhizomorpha fragilis. Later the name Rhizomorpha was sanctioned (given guaranteed priority) by Elias Magnus Fries. [3]
But the cords of R. fragilis were subsequently determined actually to belong to the well-known mushroom taxon Armillaria mellea (Honey Fungus). The genus Armillaria was not defined until 1857 and therefore according to the precedence rules of botanical and mycological nomenclature, the name Armillaria is illegitimate and needs to be replaced everywhere by Rhizomorpha. To avoid this inconvenience, in a 2021 paper covering numerous similar cases, Stalpers et al. have proposed that the name Armillaria should be protected. That decision remains to be taken by the Nomenclature Committee for Fungi and ultimately by an International Botanical Congress. [4] [2] [5]
With DNA analysis it should nowadays always be possible to assign observed material to genera in the normal taxonomic tree, and those genera should be used instead of Rhizomorpha. However it is still a legitimate genus name. [5] [3]
In 1799 James Sowerby published a mycelial cord species under the name Sphaeria hypotrichoides, which was then renamed to Rhizomorpha hippotrichoides by Fries in 1849 and later to Xylaria hippotrichoides by Pier Andrea Saccardo in 1882 when asci and spores had been observed. This species has the English vernacular name "Horsehair Candlesnuff". [6] [7]
The name Rhizomorpha should now be avoided, but at the time of writing there is still at least one species which is found only in the form of mycelial cords and for which no spore-bearing structures have been observed. This species is Brunneocorticium corynecarpon, which was originally described by Gustav Kunze in 1828 as Rhizomorpha corynecarpos. It consists of broad white aerial rhizomorphs which have frequent short branches and it occurs in the tropical forest canopy in Suriname and some other South American countries. It causes significant damage to trees and it is sometimes used by birds as nesting material. In 2018, molecular studies led it to be assigned to genus Brunneocorticium within the Marasmiaceae, a family which consists mainly of mushroom-forming genera. Other members of the Marasmiaceae, such as Marasmius crinis-equi ("Horse Hair Fungus") also have aerial rhizomorphs. [2] [8]
Numerous other species names have been assigned under genus Rhizomorpha, and the Mycobank database currently lists 96 such names. [9]
Armillaria is a genus of fungi that includes the 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. Armillarias are long-lived and form the largest living fungi in the world. The largest known organism covers more than 3.4 square miles (8.8 km2) in Oregon's Malheur National Forest and is estimated to be 2,500 years old. Some species of Armillaria display bioluminescence, resulting in foxfire.
Armillaria mellea, commonly known as honey fungus, is an edible basidiomycete fungus in the genus Armillaria. It is a plant pathogen and part of a cryptic species complex of closely related and morphologically similar species. It causes Armillaria root rot in many plant species and produces mushrooms around the base of trees it has infected. The symptoms of infection appear in the crowns of infected trees as discoloured foliage, reduced growth, dieback of the branches and death. The mushrooms are edible but some people may be intolerant to them. This species is capable of producing light via bioluminescence in its mycelium.
Spegazzinia is a genus of widely distributed mitosporic ascomycete fungi in the family Didymosphaeriaceae.As accepted by Wijayawardene et al. 2020.
Pier Andrea Saccardo was an Italian botanist and mycologist. He was also the author of a color classification system that he called Chromotaxia. He was elected to the Linnean Society in 1916 as a foreign member. His multi-volume Sylloge Fungorum was one of the first attempts to produce a comprehensive treatise on the fungi which made use of the spore-bearing structures for classification.
Mycelial cords are linear aggregations of parallel-oriented hyphae. The mature cords are composed of wide, empty vessel hyphae surrounded by narrower sheathing hyphae. Cords may look similar to plant roots, and also frequently have similar functions; hence they are also called rhizomorphs. As well as growing underground or on the surface of trees and other plants, some fungi make mycelial cords which hang in the air from vegetation.
The genus Phallus, commonly known as stinkhorns, is a group of basidiomycetes which produce a phallic, often foul-scented mushroom, from which their name is derived. The genus has a widespread distribution and, according to a 2008 estimate, contains 18 species. They belong to the family Phallaceae in the order Phallales. The best known species is the common stinkhorn.
Rhizomorpha subcorticalis is a species name that has been used to characterize certain fungal plant pathogen observations where the pathogen is evident only through mycelial cords ("rhizomorphs"). The species in question very likely also produces reproductive structures which would allow it to be situated in the normal taxonomic tree, especially if DNA analysis is available. A name like R. subcorticalis should only be used where such identification is impossible.
Xylaria hypoxylon is a species of bioluminescent fungus in the family Xylariaceae. It is known by a variety of common names, such as the candlestick fungus, the candlesnuff fungus, carbon antlers, or the stag's horn fungus. The fruit bodies, characterized by erect, elongated black branches with whitened tips, typically grow in clusters on decaying hardwood. The fungus can cause a root rot in hawthorn and gooseberry plants.
Clathrus columnatus, commonly known as the column stinkhorn, is a saprobic species of basidiomycete fungus in the family Phallaceae. Similar to other stinkhorn fungi, the fruiting body, known as the receptaculum, starts out as a subterranean "egg" form. As the fungus develops, the receptaculum expands and erupts out of the protective volva, ultimately developing into mature structures characterized by two to five long vertical orange or red spongy columns, joined at the apex. The fully grown receptaculum reaches heights of 8 cm tall. The inside surfaces of the columns are covered with a fetid olive-brown spore-containing slime, which attracts flies and other insects that help disseminate the spores.
Armillaria novae-zelandiae is a species of mushroom-forming fungus in the family Physalacriaceae. This plant pathogen species is one of four Armillaria species that have been identified in Aotearoa New Zealand the others are A. limonea,A. hinnulea, A. aotearoa).
Armillaria gallica is a species of honey mushroom in the family Physalacriaceae of the order Agaricales. 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, weigh at least 9.5 tonnes, and be 1,500 years old. This individual is popularly known as the "humongous fungus", and is a tourist attraction and inspiration for an annual mushroom-themed festival in Crystal Falls. Recent studies have revised the fungus's age to 2,500 years and its size to about 400 tonnes, four times the original estimate.
Skepperiella is a genus of fungus in the family Marasmiaceae. The widespread genus contains four species. The genus was circumscribed by Albert Pilát in Bull. Soc. Mycol. France vol.43 on page 56 in 1927.
Hymenogloea is a fungal genus in the family Marasmiaceae. The genus is monotypic, containing the single species Hymenogloea riofrioi, found in tropical America.
Armillaria root rot is a fungal root rot caused by several different members of the genus Armillaria. The symptoms are variable depending on the host infected, ranging from stunted leaves to chlorotic needles and dieback of twigs and branches. However, all infected hosts display symptoms characteristic of being infected by a white rotting fungus. The most effective ways of management focus on limiting the spread of the fungus, planting resistant species, and removing infected material. This disease poses a threat to the lumber industry as well as affecting recreational areas.
Setulipes was a proposed genus of fungi in the family Marasmiaceae. This group of mushrooms, described by the Czech mycologist Vladimír Antonín in 1987, has a widespread distribution in north temperate areas, and would contain about 25 species.
Caripia is a fungal genus in the family Marasmiaceae. The genus is monotypic, containing the single species Caripia montagnei, commonly known as the pod parachute. It is found in tropical and subtropical regions of the Americas. Formerly classified in the Stereales, molecular analysis published in 2002 demonstrated that the fungus is a reduced form of the closely related Gymnopus.
Armillaria ostoyae is a species of fungus (mushroom), pathogenic to trees, in the family Physalacriaceae. In the western United States, it is the most common variant of the group of species under the name Armillaria mellea. A. ostoyae is common on both hardwood and conifer wood in forests west of the Cascade Range in Oregon, United States. It has decurrent gills and the stipe has a ring. The mycelium invades the sapwood and is able to disseminate over great distances under the bark or between trees in the form of black rhizomorphs ("shoestrings"). In most areas of North America, Armillaria ostoyae can be separated from other species by its physical features: cream-brown colors, prominent cap scales, and a well-developed stem ring distinguish it from other Armillaria. Like several other Armillaria, the mycelium of Armillaria ostoyae can display bioluminescence, resulting in foxfire.
Leucoagaricus meleagris is a species of fungus in the family Agaricaceae.