Rhizomarasmius undatus

Rhizomarasmius undatus
Scientific classification
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Physalacriaceae
Genus:	Rhizomarasmius
Species:	R. undatus
Binomial name
Rhizomarasmius undatus (Berk.) R.H. Petersen, 2000
Synonyms [1]
Marasmius undatus(Berk.) Fr., 1849

Rhizomarasmius undatus Mycological characteristics
	Gills on hymenium
	Cap is convex
	Hymenium is adnate or subdecurrent
	Stipe is bare
	Spore print is white
	Ecology is saprotrophic
	Edibility is unknown

Rhizomarasmius undatus (syn. Marasmius undatus) is a small mushroom which grows on fern rhizomes. ^{[2] [3] [1]}

Description

The species can be described as follows: ^{[2] [3] [4]}

• The cap has a powdery covering (a pruina), is initially whitish and convex and later becomes brownish grey and expands to be flat. It grows to about 2.5 cm in diameter.
• The gills are whitish and distant, and broadly adnate to the stem, or slightly decurrent. The spore powder is white.
• The rigid stem can grow to about 12 cm long by about 2 mm in diameter. It is white at the top and dark brown to black lower down, with a puinose covering of short white hairs.
• The smell and taste are not distinctive.
• The spores are lemon-shaped to ellipsoid and measure roughly 9-12 μm x 5-7 μm.

Naming and related species

The species epithet undatus, meaning "wavy", is the past participle of the Latin verb "undo" (= "I undulate"). ^[5]

This species was originally described in 1836 as Agaricus undatus by Miles Joseph Berkeley. As it happened, in 1838 the famous mycologist Elias Magnus Fries defined a completely different mushroom (now Entoloma undatum) under the same name, but due to the nomenclatural rules of precedence, that definition is illegitimate. This was confirmed when in 1849 Fries renamed Berkeley's fungus with the combination Marasmius undatus, a name which was current for more than a century. Then in 2000 it was one of the two initial species with which R. H. Petersen created the new genus Rhizomarasmius , the other one being the type species R. pyrrhocephalus. ^{[1] [6]}

Ecology and distribution

This mushroom grows on rhizomes of bracken (Pteridium aquilinum) and probably other ferns. ^{[2] [3]} It is widespread but rare in northern and western Europe and has been reported from North Africa, North America, and the Altai Mountains. ^{[2] [4] [7]}

References

1. "Rhizomarasmius undatus page". Species Fungorum. Royal Botanic Gardens Kew. Retrieved 2018-11-13.
2. Antonín, V.; Noordeloos, M. E. (2010). A monograph of marasmioid and collybioid fungi in Europe. Berchtesgaden, DE: IHW Verlag. pp. 427–430. ISBN   978-3-930167-72-2.
3. Knudsen, H.; Vesterholt, J., eds. (2018). Funga Nordica Agaricoid, boletoid, clavarioid, cyphelloid and gasteroid genera. Copenhagen: Nordsvamp. p. 333. ISBN   978-87-983961-3-0.
4. Courtecuisse, R.; Duhem, B. (2013). Champignons de France et d'Europe (in French). Delachaux et Niestlé. p. 254. ISBN   978-2-603-02038-8. Also available in English.
5. Lewis, Charlton T.; Short, Charles. A Latin Dictionary. Oxford: Clarendon Press. Retrieved 2018-11-13.
6. "Rhizomarasmius, gen. nov. (Xerulaceae, Agaricales)". Mycotaxon. Retrieved 2018-11-13.
7. "Rhizomarasmius undatus page". mycodb.fr. Retrieved 2017-11-13.