Marasmius rotula

Marasmius rotula Scientific classification Kingdom: Fungi Division: Basidiomycota Class: Agaricomycetes Subclass: Hymenomycetes Order: Agaricales Family: Marasmiaceae Genus: Marasmius Species: M. rotula Binomial name Marasmius rotula (Scop.) Fr. Synonyms Agaricus rotula Scop. Androsaceus rotula (Scop.) Pat. Chamaeceras rotula (Scop.) Kuntze Merulius collariatus With. Micromphale collariatum (With.) Gray Marasmius rotula Mycological characteristics gills on hymenium cap is convex hymenium is free stipe is bare spore print is white ecology is saprotrophic edibility: inedible

Marasmius rotula is a species of fungus in the Marasmiaceae family of mushrooms. It is commonly known variously as the pinwheel mushroom, the pinwheel Marasmius, the little wheel, the collared parachute, or the horse hair fungus. It is a widespread and common fungus, and is the type species of the genus Marasmius. The fruit body is characterized by its whitish, thin, membranous cap, its long and slender but tough black stem, and widely-spaced white gills that are attached to a collar encircling but not touching the stem. The fungus grows on decaying wood and leaves. Unlike other mushrooms known to release spores in response to an internal timer, or circadian rhythm, spore release in M. rotula is dependent on rain.

Taxonomy

The species was first named by Italian mycologist Giovanni Antonio Scopoli as Agaricus rotula in 1772. In 1821 Elias Magnus Fries redescribed the mushroom,^[1] and later sanctioned the name as Marasmius rotula in 1838.^[2] In 1946 Smith and Singer proposed to conserve the genus name Marasmius over Micromphale, which had nomenclatorial priority, with M. rotula as the lectotype.^[3] The genus Marasmius, with M. rotula as the lectotype species, was later conserved by the 1954 Paris Congress on Botanical Nomenclature.^[4][5]

It is commonly known as the "pinwheel mushroom", the "pinwheel Marasmius",^[6] the "collared parachute",^[7] or the "horse hair fungus".^[8] The name "little wheel fungus" is suggestive of the collar to which the gills are attached like the spokes of a wheel.^[9] The specific epithet is derived from the Latin word rota meaning "wheel".^[6]

Description

The gills are attached to a collar that is free from the stem.

The cap of the fruit body is thin and membranous, measuring 3 to 20 mm (0.1 to 0.8 in) in diameter.^[10] It has a convex shape, and is slightly depressed in the center. The cap color is whitish to light pinkish-white, slightly darker at the center, and smooth. The cap margin has scalloped edges and furrows that outline the shape of the gills on the underside; the radial furrows extend inward to one-third to three-quarters of the cap radius from the edge.^[11] The flesh is thin and white.

The gills are attached to a collar, and are free from direct attachment to the stem, although some specimens may have the collar pressed close to the stem and this characteristic will be less obvious.^[6] The gills are whitish-pallid, widely-spaced; there are typically between 16 and 22 of them.^[12] The stem is 2 to 5 cm (0.8 to 2.0 in) long and up to 0.1 cm (0.04 in) thick, with a smooth, sometimes shiny surface. It is tough, hollow, slightly blackish-brown below, with a lighter apex that is almost translucent.^[13] The base of the stem may be connected to black root-like rhizomorphs. There is no partial veil on the stem.^[8]

Microscopic characteristics

Viewed in deposit, such as with a spore print, the spores of Marasmius rotula appear white or pale yellow.^[11] Viewed with a light microscope, the spores are hyaline (translucent), teardrop or pip-shaped, and have dimensions of 7–10 by 3–5 µm.^[8] The basidia (the spore-producing cells) are four-spored. Along the edge of the gill, interspersed among the basidia, are sterile (non-reproductive) cells called cystidia; they are club-shaped and have rough wart-like protuberances on the surface.^[12]

Edibility

Marasmius rotula is considered inedible,^[6] but not poisonous. The mushroom has no distinguishable odor, and the taste is mild or bitter.^[8] The fruit bodies have the ability to bioaccumulate the heavy metal cadmium; a study of the metal concentration of 15 wild Indian mushroom species showed that M. rotula had accumulated the highest concentration of cadmium.^[14]

Spore release

In 1975 American mycologist Martina S. Gilliam investigated the periodicity of spore release in M. rotula and concluded that spore discharge did not follow the regular circadian rhythm like other typical agaric and bolete mushrooms,^[15] but rather, was dependent on rain.^[16] Like many other species of Marasmius, the fruit bodies of M. rotula can dry out in dry periods, and revive when sufficient moisture is available in the form of rain or high humidity. In her study, fruit bodies were capable of discharging spores over a period of at least three weeks.^[16]

Similar species

The lookalike species Marasmius capillaris typically grows on leaves.

Marasmius capillaris has a roughly similar appearance, but with a pale tan cap with a white center, and it grows on oak leaves, and is never clustered.^[10] Further, its cap is evenly rounded, unlike M. rotula, which is pleated and furrowed.^[17] Marasmius nigripes has white caps that are 5 to 10 mm (0.2 to 0.4 in), widely-spaced gills, and a dark stem covered with what appears to be a white powder.^[18] Mycena corticola is smaller than Marasmius rotula, has a pale pink-brown cap, and can is usually found growing singly or in groups on bark near the base of living trees.^[6] M. rotula is distinguished from M. bulliardi by its larger size, and greater number of gills.^[12]

Habitat and distribution

Marasmius rotula is a saprobic species,^[17] and obtains nutrients by decomposing dead organic matter. It grows on rotten leaves, dead wood (especially beech), or other woody debris in deciduous forests. The fruit bodies are easily overlooked because of their diminutive size.^[9]

The fungus is widespread and common in the British Isles, and has been collected in Shetland (Scotland),^[19] Nigeria,^[20] India,^[14] China,^[13] and Poland.^[21] In North America it is more commonly found in the east.^[8]

References

1. ^ Fries EM (1821). Systema Mycologicum. 1. ex officina Berlingiana. p. 136. http://194.203.77.76/librifungorum/Image.asp?ItemID=21&ImageFileName=0136b.jpg. Retrieved 2010-01-05. 
2. ^ Fries EM (1838). Epicrisis Systematis Mycologici. Uppsala, Sweden: Typographia Academica. p. 385. http://books.google.com/?id=sLQTAAAAQAAJ&dq=Epicrisis%20Systematis%20Mycologici&pg=RA1-PA385#v=onepage&q=. Retrieved 2010-01-07. 
3. ^ Singer R, Smith AH (1946). "Proposals concerning the nomenclature of the gill fungi, including a list of proposed lectotypes and genera conservation". Mycologia 38 (3): 240–99. doi:10.2307/3755094. JSTOR 3755094. 
4. ^ Anon (1953). "Disposition of nomina generica conservanda for Fungi". Taxon 2 (2): 29–32. JSTOR 1217581. 
5. ^ Anon (1954). "Nomina generica conservanda". Taxon 3 (8): 233. doi:10.2307/1216603. JSTOR 1216603. 
6. ^ ^{a b c d e} Roody WC (2003). Mushrooms of West Virginia and the Central Appalachians. Lexington, Ky: University Press of Kentucky. ISBN 0-8131-9039-8. 
7. ^ Phillips R. "Marasmius rotula". RogersMushrooms. Rogers Plants Ltd. http://www.rogersmushrooms.com/gallery/DisplayBlock~bid~6400.asp. Retrieved 2010-01-05. 
8. ^ ^{a b c d e} Miller HR, Miller OK (2006). North American Mushrooms: a Field Guide to Edible and Inedible Fungi. Guilford, Conn: Falcon Guide. p. 196. ISBN 0-7627-3109-5. http://books.google.com/?id=zjvXkLpqsEgC&lpg=PA195&dq=marasmius%20rotula&pg=PA196#v=onepage&q=marasmius%20rotula. Retrieved 2010-01-05. 
9. ^ ^{a b} Orr DB, Orr RT (1979). Mushrooms of Western North America. Berkeley: University of California Press. p. 240. ISBN 0-520-03656-5. 
10. ^ ^{a b} Bessette A, Bessette AR, Fischer DW (1997). Mushrooms of Northeastern North America. Syracuse University Press. pp. 201–202. ISBN 978-0815603887. http://books.google.com/?id=T2uU12XcRD4C&lpg=PA201&dq=marasmius%20rotula&pg=PA201#v=onepage&q=marasmius%20rotula. Retrieved 2010-01-05. 
11. ^ ^{a b} McKnight VB, McKnight KH (1987). A Field Guide to Mushrooms, North America. Boston: Houghton Mifflin. p. 167. ISBN 0-395-91090-0. http://books.google.com/?id=kSdA3V7Z9WcC&lpg=PA167&dq=marasmius%20rotula&pg=PA167#v=onepage&q=marasmius%20rotula. Retrieved 2010-01-05. 
12. ^ ^{a b c} Jordan M (2004). The Encyclopedia of Fungi of Britain and Europe. London: Frances Lincoln. p. 191. ISBN 0-7112-2378-5. http://books.google.com/?id=ULhwByKCyEwC&lpg=PA191&dq=marasmius%20rotula&pg=PA191#v=onepage&q=marasmius%20rotula. Retrieved 2010-01-05. 
13. ^ ^{a b} Wen, H-A, Sun, S-X (1999). "Fungal flora of tropical Guangxi, China: Macrofungi". Mycotaxon: 359–69. http://www.cybertruffle.org.uk/cyberliber/59575/0072/0359.htm. Retrieved 2010-01-01. 
14. ^ ^{a b} Das N (2005). "Determination of lead, arsenic, cadmium, iron, copper and nickel in wild mushroom samples from South West Bengal". Mushroom Research 14 (2): 80–83. 
15. ^ Roenneber T, Merrow M (2001). "Seasonality and Photoperiodism in Fungi". Journal of Biological Rhythms 16 (4): 403–14. doi:10.1177/074873001129001999. PMID 11506384. 
16. ^ ^{a b} Gilliam MS (1975). "Periodicity of spore release in Marasmius rotula". Michigan Botanist 14 (2): 83–90. ISSN 0026-203X. 
17. ^ ^{a b} Kuo M. "Marasmius rotula". MushroomExpert.Com. http://www.mushroomexpert.com/marasmius_rotula.html. Retrieved 2010-01-05. 
18. ^ Healy RA, Huffman DR., Tiffany LH, Knaphaus G (2008). Mushrooms and Other Fungi of the Midcontinental United States (Bur Oak Guide). Iowa City: University of Iowa Press. p. 143. ISBN 1-58729-627-6. http://books.google.com/?id=tl2fVAHuej4C&lpg=PT124&dq=marasmius%20rotula&pg=PT124#v=onepage&q=marasmius%20rotula. Retrieved 2010-01-05. 
19. ^ Watling R, King R, Riddiford N (2001). "New and interesting records of fungi from Shetland". Botanical Journal of Scotland 53 (1): 57–64. doi:10.1080/03746600108684955. ISSN 1359-4869. 
20. ^ Idu M, Osemwegie OO, Onyibe HI (2008). "Checklist of flora in Edo State, Nigeria". Plant Archives 8 (2): 539–49. ISSN 0972-5210. 
21. ^ Lisiewska M (1994). "Marasmius and allied genera in forest communities of the Bialowieza National Park". Acta Mycologica 29 (1): 59–67. ISSN 0001-625X.