Mycena Adscendens
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''Mycena adscendens'', commonly known as the frosty bonnet, is a species of
fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
in the family Mycenaceae. The fungus produces small white fruit bodies (
mushroom A mushroom or toadstool is the fleshy, spore-bearing Sporocarp (fungi), fruiting body of a fungus, typically produced above ground on soil or another food source. ''Toadstool'' generally refers to a poisonous mushroom. The standard for the n ...
s) with caps up to in diameter that appear to be dusted with sugar-like granules. Caps are supported by thin, hollow stems up to long, which are set on a disc-like base. Its distribution includes Europe, Turkey and the Pacific coast of the United States. The fruit bodies grow on fallen twigs and other woody debris on the forest floor, including fallen hazel nuts. The variety ''carpophila'' is known from Japan. There are several small white '' Mycena'' species that are similar in appearance to ''M. adscendens'', some of which can be reliably distinguished only by examining microscopic characteristics.


Taxonomy

The species, originally named ''Agaricus adscendens'' by Wilhelm Gottfried Lasch in 1829, was first collected in the Province of Brandenburg, in what was then the
Kingdom of Prussia The Kingdom of Prussia (, ) was a German state that existed from 1701 to 1918.Marriott, J. A. R., and Charles Grant Robertson. ''The Evolution of Prussia, the Making of an Empire''. Rev. ed. Oxford: Clarendon Press, 1946. It played a signif ...
(now Germany). It was Dutch mycologist Maas Geesteranus who assigned the species its current name in a 1981 publication. According to Maas Geesteranus, Miles Berkeley's 1836 ''Agaricus tenerrimus'' is the same species as ''Mycena adscendens'', as well as all later
synonyms A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
based on this
basionym In the scientific name of organisms, basionym or basyonym means the original name on which a new name is based; the author citation of the new name should include the authors of the basionym in parentheses. The term "basionym" is used in both botan ...
: ''Mycena tenerrima'', published by Lucien Quélet in 1872; ''Prunulus tenerrimus'' by
William Alphonso Murrill William Alphonso Murrill (October 13, 1869 – December 25, 1957) was an American mycologist, known for his contributions to the knowledge of the Agaricales and Polyporaceae. In 1904, he became the assistant Curator at the New York Botanical Ga ...
in 1916; and Karel Cejp's 1930 ''Pseudomycena tenerrima''. Although
Index Fungorum ''Index Fungorum'' is an international project to index all formal names (scientific names) in the fungus kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and th ...
agrees with Maas Geesteranus's synonymy, other authorities treat the species as independent. An additional synonym is ''Agaricus'' (''Mycena'') ''farinellus'', described by Johann Feltgen from Luxembourg in 1906. The variety ''M. adscendens'' var. ''carpophila'', published by Dennis Desjardin in 1995, was originally proposed as ''M. tenerrima'' var. ''carpophila'' by Jakob Emanuel Lange in 1914. ''Mycena adscendens'' is the
type species In International_Code_of_Zoological_Nomenclature, 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 spe ...
of section ''Sacchariferae'' of the genus ''Mycena'', which contains white species with floccose caps (covered with tufts of soft woolly hairs). Other members of this section include '' M. floccifera'', '' M. discopus'', and '' M. nucicola''. The mushroom is commonly known as the "frosty bonnet". The
specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
''adscendens'', derived from the
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
, means "ascending" or "curving up from a prostrate base". ''Tenerrima'' derives from the Latin ''tener'', meaning "tender" or "delicate".


Description

The
cap A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. The origin of the word "cap" comes from the Old French word "chapeau" which means "head co ...
is white and small, with a diameter typically ranging from . Initially convex to cucullate (hood-shaped), it flattens during maturity, developing visible surface grooves that correspond to the gills underneath the cap; the surface may also be covered with glistening particles, remnants of the
partial veil In mycology, a partial veil (also called an inner veil, to differentiate it from the "outer", or universal veil) is a temporary structure of tissue found on the fruiting bodies of some Basidiomycota, basidiomycete fungus, fungi, typically agarics. ...
. The cap is pallid gray with a whitish margin when young, but soon becomes white overall. The flesh is membranous, fragile, and thin (less than 0.5 mm). The gills are free from attachment or narrowly attached (adnexed) to the
stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...
. They are up to 0.5 mm broad, distantly-spaced (usually numbering between 7 and 12), and sometimes adhering to each other to form a slight collar (a ''pseudocollarium'') around the stem. They are translucent-white throughout their development, with a fringed, white edge. The hollow stem is long, and usually curved and threadlike. The bottom of the stem is enlarged into a slight bulb, which is initially nearly spherical.Smith (1947)
pp. 45–7.
/ref> At the very base of the stem is a small, white, and hairy disk-like base that attaches to the substrate. The edibility of the mushroom is unknown, but like many small Mycenas, they are insubstantial and not likely to be considered for the table. The variety ''carpophila'' is characterized by its tiny white cap up to 1 mm in diameter, and narrowly conical caulocystidia ( cystidia found on the stem).


Microscopic characteristics

''Mycena adscendens'' produces a white spore print. The
spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...
s are broadly
ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface;  that is, a Surface (mathemat ...
,
amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...
, and have dimensions of 8–10 by 5–6.5  μm. Basidia (spore-bearing cells) are two-spored, club-shaped, and measure 14–17 by 7–9 μm. Pleurocystidia (cystidia on the gill faces) may be present or absent. If present, they are similar to the cheilocystidia (cystidia on the gill edges). The cheilocystidia are abundant, measuring 28–44 by 8–12 μm. They are variable in shape, often fusoid-ventricose (fuse-shaped with a swollen center) or with 2–3 needle-like projections arising from the apex; the projections are sometimes forked. The swollen parts of the cheilocystidia are covered with short rodlike protuberances or warts. The flesh of the gills is vinaceous-brown when stained in
iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
. The flesh of the cap is made up of greatly enlarged cells, with the surface covered with club-shaped to almost globular cells measuring 25–40 by about 20 μm. Their walls are finely verrucose (covered with small warts), and all but the verrucose cells are vinaceous-brown in iodine. Clamp connections are abundant in the hyphae.


Similar species

Other Mycenas that resemble ''M. adscendens'' include '' M. alphitophora'' and '' M. stylobates''. The former is distinguished from ''M. adscendens'' by a stem base that is not swollen or disc-like, the latter by its larger and sturdier fruit body and lack of granules on the cap. A poorly known Japanese species, '' M. cryptomeriicola'', is similar to ''M. adscendens'', but has non-amyloid spores and lacks clamps. '' M. nucicola'' is most reliably distinguished from ''M. adscendens'' by microscopic characteristics: ''M. nucicola'' has four-spored basidia, clamp connections are rare in the hyphae of the gill tissue, and the spores are less broad (typically 4.2–5 μm). The Finnish species '' M. occulta'' grows on the decaying needles of
Norway spruce ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, 9–17 cm long. It is very clo ...
and
Scots pine ''Pinus sylvestris'', the Scots pine (UK), Scotch pine (US), Baltic pine, or European red pine is a species of tree in the pine family Pinaceae that is native to Eurasia. It can readily be identified by its combination of fairly short, blue-gr ...
. It differs from ''M. adscendens'' in that its gills do not form a pseudocollarium, it lacks clamps in the hyphae and cells of the hymenium, and the terminal cells in its cap cuticle are densely covered with protuberances.


Habitat and distribution

Fruit bodies of ''Mycena adscendens'' are found scattered to grouped together in twos or threes on fallen twigs, bark, and woody debris of
hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...
s during the spring and autumn; it fruits less frequently on the wood of
conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...
s. Fruitings are most common after periods of wet weather. They are also found growing on hazel nuts that have fallen to the ground; two other Mycenas known to grow on this substrate include ''M. discopus'' and ''M. nucicola''. In the United States, it is known from Washington to
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
. It is also found in Europe, and has been collected in Amasya Province, Turkey. The variety ''carpophila'', originally described from Denmark, was reported from Japan in 2003.


References


Cited text

* {{Taxonbar, from=Q5789046 adscendens Fungi described in 1829 Fungi of Asia Fungi of Europe Fungi of North America Fungus species