Usnea longissima

Methuselah's beard lichen
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Lecanorales
Family:	Parmeliaceae
Genus:	Usnea
Species:	U. longissima
Binomial name
Usnea longissima Ach.

Lichen Usnea 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

Usnea longissima, old man's beard or Methuselah's beard lichen, is a lichen in the family Parmeliaceae.

Name[]

Usnea longissima has also been named Dolichousnea longissima,^[1] but this is not the currently accepted name for this lichen.^[2]

Distribution[]

Usnea longissima is found in boreal forests and coastal woodland in Europe, Asia, and North America.^[3]

Description[]

This lichen is fruticose, with very long stems and short, even side branches. It is considered the longest lichen in the world.^[4] The stems are usually 15 to 30 cm in length but are sometimes much longer.^[5]

Ecology[]

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].

References[]

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