In addition to the the leaves and needles that they produce themselves, trees in the Pacific Northwest are often covered with teeming masses of little plants and lichens.
Some of these lichens hang from tree branches like shaggy beards, giving the forest an ancient, mystical look. Beard lichens might have inspired J. R. R. Tolkien when he created Fangorn Forest and the walking, talking tree creatures called Ents.
Plants and lichens that grow on the surface of a host plant, without actually doing any harm to the host plant, are called epiphytes. Many epiphytes use trees as support platforms so that they can get up off the ground. What do epiphytes gain by living up in the branches? More sunlight and safety from herbivorous animals that can’t climb trees.
There are numerous species of ferns, mosses, and lichens that live as epiphytes in the northwest. Beard lichens are some of the most conspicuous.
I’ll quickly explain what a lichen is. It is actually two distantly-related species living together: a fungus and an alga. The fungus provides the overall structure of the lichen. Most of what you are looking at when you see a lichen is the fungus. Just under the surface of the fungus is a layer of microscopic algae cells. The algae convert sunlight into sugars through photosynthesis (like plants) and the sugars are eaten by the fungus. The relationship is mutually beneficial because the algae are sheltered from the outside world by the fungus.
So, even though lichens are often green and they sometimes look like plants, they are definitely not plants.
The term ‘beard lichens’ does not describe an officially-recognized group. This is just the common term for lichens that have a beard-like appearance. In our region, there are several types of lichen that have this form. And by types, I mean genera, the plural form of the word genus.
Lichens in the genus Usnea are generally called ‘old man’s beard.’ The species Usnea longissima, known as Methuselah’s Beard Lichen, can have fibers over 10 feet (3 m) long! This species, like many lichens, is very sensitive to air pollution and can grow to such lengths only where the air is very clean. It grows in moist forests around the world, although its range is shrinking as pollution takes its toll. The Pacific Northwest is one of the last strongholds of this lichen.
Each pale green branches of an Usnea lichen has a single, central cord.
The very similar-looking Alectoria lichens don’t have this central cord. The photo at the top of this post and the one below are of Alectoria sarmentosa, a species that hangs from the branches of conifers (such as the Mountain Hemlocks in the photos) in cool, moist forests.
The shaggy Bryoria lichens are generally brown or grayish in color, instead of green like Usnea and Alectoria.
In low-elevation valleys, you might see Ramalina menziesii hanging from an oak tree. This beard lichen has the common name Lace Lichen. People sometimes call it ‘Spanish moss,’ but this is incorrect because Ramalina is definitely not a moss. The real Spanish moss is a flowering plant (and therefore also not a moss) that grows in the southeastern U.S.
It should come as no surprise that birds and squirrels often use beard lichens to make their nests. The lichen fibers are fairly soft and provide some insulation.
Beard lichens maximize their exposure to sunlight, moisture, and air by having large surface areas– more strands means more surface area– and by hanging down from tree branches, away from leaves or needles. They have evolved a fascinating way of making a living in the dense forests of the northwest and elsewhere.