This is one of the rare lichens with an accepted common name. Usnea as a whole are often called beard lichens, or old man’s beard, but every resource I looked at that gave any common names listed Methuselah’s Beard for Usnea longissima, and most of them only listed this one.
Speaking of names, the genus of this species has been called into question. A 2004 paper by Japanese researchers placed it in its own monotypic genus, Dolichousnea, based on DNA testing. But there is apparently resistance, and many peer reviewed papers from recent years still place it in Usnea.
Usnea sp. are fairly easy to identify to genus because fresh specimens are stretchy! This is because they have an elastic, strong, dense, central inner cord (axis). Pendulous Usnea like Methuselah’s Beard often end up draping multiple branches, and the elasticity of the cord keeps them from breaking when the branches are moving in different directions in the wind.
Usnea longissima used to be common and widespread in Europe and North America, but it is sensitive to air pollution and its population has declined drastically, especially in Europe. In the US it can still be found occasionally in good numbers away from population centers, although it faces other threats from collection for the floral trade. Here’s a fun fact: the original tinsel for Christmas tree decoration was made from Methuselah’s Beard (and according to David Wagner some folks call it tinsel moss for that reason, even though it is not a moss. See why I don’t like common names?)
One of the biggest reasons that collecting it is so problematic is that it has limited means for dispersal. It lacks apothecia and isidia, and soredia are only rarely present. It spreads by pieces, usually the fibrils, that have broken off, and, due to its arboreal nature, changes are slim that one of them will land in a suitable spot for propagation, or that it will travel more than 15’ from the parent organism.
Native peoples had many uses for this lichen including diapers, bedding, and straining medicines and pitch. Herbalists, especially Chinese and Vedic practitioners, use it as an expectorant and respiratory antibiotic. But really, its numbers no longer support collection for any purposes beyond limited scientific study by experts in the field. The small piece I brought home to photograph was found as blowdown on a gravel road, and I left 90% of that where I found it.
Description– Very distinctive lichen, and the only Usnea that I can identify in situ; long (up to 20’), pendulous gray green fruticose thallus; narrow, with an unbranched stem with numerous short tendrils and fibrils; the cortex of the stem scales off leaving a patchy and rough surface; lacks papillae, apothecia, isidia, and usually soredia; central cord thick and dark colored;
Similar species– This is the only unbranched Usnea with perpendicular tendrils and fibrils; some Ramalina and Alectoria may be superficially similar, but lack elastic central cord.
Habitat– Usually found on riparian trees; most abundant in old growth forests, but that is probably due to its limited dispersal capabilities. It has been found to do very well in reforested areas, if it is introduced into the ecosystem; most common in the transitional band between montane and foothill environments.
Range– West slope of the Cascades and in the Coast Range.
Eaten by– Used as a nesting material by some birds and terrestrial salamanders.
Etymology of names– Usnea comes from the Arabic ‘oosnah’ for moss, a common misnaming from before people understood the true nature of lichens. The epithet longissima means ‘longest’ in Latin, and is completely accurate since Usnea longissima is the longest lichen in the world.