Dolichousnea Longissima on:
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''Dolichousnea longissima'' ( syn. ''Usnea longissima''), commonly known by the names old man's beard or Methuselah's beard lichen, is a
''Dolichousnea longissima'' ( syn. ''Usnea longissima''), commonly known by the names old man's beard or Methuselah's beard lichen, is a fruticose lichen
A fruticose lichen is a form of lichen fungi that is characterized by a coral-like shrubby or bushy growth structure. It is formed from a symbiotic relationship of a photobiont such as green algae or less commonly cyanobacteria and one, two or mor ...
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'' ( 822 ...
.
Description
This lichen is fruticose, with very long stems and short, even side branches. It is considered the longest lichen in the world. The stems are usually 15 to 30 cm in length but are sometimes much longer. It is pale green to silvery-yellow. It has a distinct central cord, which is white. ''D. longissima'' may grow to be 20 feet in length. It predominantly reproduces asexually through fragmentation. Spore-producing structures are rarely observed. It can double its length each year.Distribution
''Dolichousnea longissima'' is found inboreal forests
Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces ...
and coastal woodland in Europe, Asia, and North America. In North America, it is primarily found on the Pacific Coast, and the largest populations are concentrated in the Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
. It ranges from Upper Midwest into Canada, the Great Lakes region, and extends to the coast of the Atlantic ocean. It was historically circumboreal
The Circumboreal Region in phytogeography is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan.
It is the largest floristic region in t ...
, but has been regionally extirpated from areas of Europe and Scandinavia. It has been placed on the Red List of
California Lichens, and is considered Endangered in the Norwegian Red List.
The species grows within the canopies of coniferous trees, primarily those found in old growth Douglas fir
The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...
forests and near bodies of water. Air pollution heavily affects the metabolic functions of the species, and as a result, populations have declined. Industrial logging has also had detrimental impacts on population numbers.
Human use
The species is harvested for decoration. It has also been historically used as a bedding and filtering material. Medicinally, ''D. longissima'' is known as an anti-inflammatory due to the presence of the compound longissiminone. It has been described in Chinese herbal medicine dating back to 500 A.D., where one of the names for the species translates to "pine gauze".References
{{Taxonbar, from1=Q1809933, from2=Q22111343 Parmelia Lichen species Lichens described in 1810 Taxa named by Erik Acharius Lichens of Asia Lichens of Europe Lichens of North America