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 family Parmeliaceae. It grows all over the world. Members of the genus are commonly called old man's beard, beard lichen, or beard moss. Like other lichens it is a symbiosis of two or three fungi and an alga. In ''Usnea'', the fungus belongs to the division Ascomycota, while the alga is a member of the division Chlorophyta. Members of the genus are similar to those of the genus '' Alectoria''. A distinguishing test is that the branches of ''Usnea'' are somewhat elastic, but the branches of ''Alectoria'' snap cleanly off. Systematics The genus ''Usnea'' was circumscribed by Michel Adanson in 1763. He used the name designated by Johann Jacob Dillenius, whose earlier published description did not met the rules of valid publication as ...
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Dolichousnea Longissima
''Dolichousnea longissima'' (syn. ''Usnea longissima''), 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. 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 in boreal forests 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. It ranges from Upper Midwest into Canada, the Grea ...
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