Usnea longissima


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, but this is not the currently accepted name for this lichen.

Distribution

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

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.

Ecology

The most frequent host of this lichen is spruce trees. It is currently on threatened status.
It grows on old trees, deciduous or coniferous, including on this nearly 100 year old pear in the Dosewallips river delta of western Washington .