Long pendulous thallus of Usnea cavernosa, found on conifers in Rocky Mountain National Park, the San Juan Mountains, and other high elevations in Colorado. Not common here; this scan is of a specimen from Idaho.
Some fruticose lichens form long webs, dangling from tree branches, that acquire common names like “tree hair” or “old man’s beard,” especially in places like the Pacific Northwest, where high humidity and tall trees support their robust expression. From a distance, these resemble the “Spanish moss” of southern states (which is neither moss nor lichen).
Common species of Usnea, such as U. hirta and U. subfloridana, occur on conifer bark and are small and shrubby. At higher elevations with adequate moisture, larger species like U. cavernosa (at top) may be seen.
More common in our Colorado forests are species of Usnea
that display themselves less dramatically. Most are no more than a few inches tall (or long) and are frequently seen on bark of conifers like Douglas-fir and Colorado or Engelmann spruce. (Oddly, however, not on ponderosa pine.)
A closer view of this same specimen is below; click to enlarge further.
A close-up of the same lichen shows the tangled branches characteristic of the Usnea thallus. Each branch has a tough central cord, which distinguishes this genus from other light-green arboreal genera, like Evernia and Ramalina.
Detailed description of Usnea cavernosa
More Usnea photos (at Ways of Enlichenment)
List of Usnea species and photos (at Sharnoff Lichens)