About Usnea hirta (L.) F.H.Wigg.
Usnea hirta (L.) F.H.Wigg. is a species of beard lichen that belongs to the Parmeliaceae family. It was among the 80 lichen species first formally described by Carl Linnaeus in his 1753 publication Species Plantarum. Friedrich Heinrich Wiggers reclassified it into the genus Usnea in 1780. This lichen is sensitive to air pollution, so it is frequently used as a biomonitor for sulphur dioxide. Usnea hirta has a broad worldwide distribution and high morphological variation; over its taxonomic history, this variation has resulted in the proposal of many intraspecific taxa, including subspecies, varieties, and forms.
