Dolichousnea longissima explained

Dolichousnea longissima (syn. Usnea longissima),[1] [2] commonly known by the names old man's beard or Methuselah's beard lichen, is a fruticose lichen in the family Parmeliaceae.

Description

This lichen is fruticose, with very long stems and short, even side branches. It is considered the longest lichen in the world.[3] The stems are usually 15 to 30 cm in length but are sometimes much longer.[4] It is pale green to silvery-yellow. It has a distinct central cord, which is white.[5]

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 in boreal forests and coastal woodland in Europe, Asia, and North America.[6] In North America, it is primarily found on the Pacific Coast, and the largest populations are concentrated in the Pacific Northwest. It ranges from Upper Midwest into Canada, the Great Lakes region, and extends to the coast of the Atlantic ocean.[7] It was historically circumboreal, but has been regionally extirpated from areas of Europe and Scandinavia.[5] It has been placed on the Red List ofCalifornia Lichens, and is considered Endangered in the Norwegian Red List.[5] [8]

The species grows within the canopies of coniferous trees, primarily those found in old growth Douglas fir forests and near bodies of water. Air pollution heavily affects the metabolic functions of the species, and as a result, populations have declined.[7] Industrial logging has also had detrimental impacts on population numbers.[8]

Human use

The species is harvested for decoration.[5] It has also been historically used as a bedding and filtering material.[7] Medicinally, D. longissima is known as an anti-inflammatory due to the presence of the compound longissiminone.[9] 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".[3]

See also

Notes and References

  1. Articus, K. (2004) Neuropogon and the phylogeny of Usnea s.l. (Parmeliaceae, lichenized Ascomycetes). Taxon 53(4): 925–934.
  2. Esslinger, TL. (2018) A Cumulative Checklist for the Lichen-Forming, Lichenicolous and Allied Fungi of the Continental United States and Canada, Version 22. Opuscula Philolichenum 17: 6-268. http://sweetgum.nybg.org/science/op/biblio_details.php?irn=480859
  3. Web site: Usnea longissima . lichen.com . Lichens of North America . 10 July 2022 . https://web.archive.org/web/20120503045319/https://www.lichen.com/bigpix/Ulongissima.html . 3 May 2012.
  4. Book: Walewski, Joe . Lichens of the North Woods . Kollath-Stensaas . Duluth, MN. 2007 . 0-9792006-0-1 .
  5. Web site: Fact Sheet for Usnea longissima . blm.gov . Bureau of Land Management . 10 July 2022.
  6. "Fact Sheet: Usnea longissima in Norway." Nov 08, 1996.http://www.toyen.uio.no/botanisk/bot-mus/lav/factshts/usnelong.htm (accessed Dec 19, 2008).
  7. Web site: DeLay . Chantelle . Bearded Lichen . www.fs.fed.us . 10 July 2022.
  8. Storaunet . Ken Olaf . Rolstad . Jørund . Rolstad . Erlend . Effects of logging on the threatened epiphytic lichen Usnea longissima: an experimental approach . Silva Fennica . 2014 . 48 . 1 . 10.14214/sf.949 . 10 July 2022. free .
  9. Choudhary . Muhammad I. . Jalil . Saima . Bioactive phenolic compounds from a medicinal lichen, Usnea longissima . Phytochemistry . October 2005 . 66 . 19 . 2346–2350 . 10.1016/j.phytochem.2005.06.023 . 10 July 2022.