Usnea longissima

Usnea longissima, old man's beard or Methuselah's beard lichen, is a lichen in the family Parmeliaceae. Usnea longissima has also been named Dolichousnea longissima, but this is not the currently accepted name for this lichen. Usnea longissima is found in boreal forests and coastal woodland in Europe, Asia, and North America. 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. The most frequent host of this lichen is spruce trees. It is currently on threatened status.