''Usnea hirta'' is a species of beard lichen in the family

Parmeliaceae The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: '' Xanthoparmelia'' ( ...

. It was one of 80 lichen species first formally described by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

in his 1753 work '' Species Plantarum''.

Friedrich Heinrich Wiggers Friedrich Heinrich Wiggers (15 March 1746 – 3 March 1811) was a German botanist who wrote a flora of Holstein in 1780. A number of variants of his name exist, including "Fridrich Hindrich" and the Latinisation "Fredericus Henricus" and the alter ...

transferred it to the genus ''

Usnea ''Usnea'' is a genus of mostly pale grayish-green fruticose lichens that grow like leafless mini-shrubs or tassels anchored on bark or twigs.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, The genus is in the f ...

'' in 1780. The lichen is sensitive to

air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different typ ...

, and is often used as a biomonitor of sulphur dioxide. ''Usnea hirta'' has an extensive worldwide distribution, and it is morphologically variable, which has led to numerous intraspecific taxa (i.e. subspecies,

varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

, and

forms Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to write or enter data * ...

) being proposed in its taxonomic history.

References

hirta Hirta ( gd, Hiort) is the largest island in the St Kilda archipelago, on the western edge of Scotland. The names (in Scottish Gaelic) and ''Hirta'' (historically in English) have also been applied to the entire archipelago. Now without a perman ...

Lichen species Lichens described in 1753 Taxa named by Carl Linnaeus Lichens of Africa Lichens of Europe Lichens of North America Cosmopolitan species {{Parmeliaceae-stub