Dolichousnea longissima

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Methuselah's beard lichen
Usnea longissima.jpg
Scientific classification
D. longissima
Binomial name
Dolichousnea longissima
Lichen Dolichousnea longissima growing on a conifer in the hills north of Mount St. Helens, showing the leaf-like side-branches and pendent "stems", some of them several metres long

Dolichousnea longissima, old man's beard or Methuselah's beard lichen, is a lichen in the family Parmeliaceae. It was previously known as Usnea longissima.[1]


Dolichousnea longissima is found in boreal forests and coastal woodland in Europe, Asia, and North America.[2]


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]


The most frequent host of this lichen is spruce trees. It is currently on threatened status.[citation needed]

It grows on old trees, deciduous or coniferous, including on this nearly 100 year old pear in the Dosewallips river delta of western Washington [picture needed].


  1. ^ Articus, K. (2004) Neuropogon and the phylogeny of Usnea s.l. (Parmeliaceae, lichenized Ascomycetes). Taxon 53(4): 925-934.
  2. ^ "Fact Sheet: Usnea longissima in Norway." Nov 08, 1996. Archived March 30, 2007, at the Wayback Machine (accessed Dec 19, 2008).
  3. ^ Sharnoff, S.. "'Usnea longissima..'." (accessed Dec 19, 2008).
  4. ^ Walewski, Joe (2007). Lichens of the North Woods. Duluth, MN: Kollath-Stensaas. ISBN 0-9792006-0-1.