Shrubby lichens like the bushy beard (Usnea strigosa) are sensitive enough to air pollution to be bioindicators: the bushier the beards, the cleaner the air. Judging by the robustness of the specimen growing on a tree alongside West Road at the Wellfleet Bay Wildlife Sanctuary, it appears we can breathe easy here on the Outer Cape. Unless, of course, you happen to be the tree the lichen is perched on: Usnea strigosa is often found on dying or dead wood. Bushy beard lichen isn’t the cause of a tree’s decline, though; it simply takes advantage of the brighter light that a diminished canopy provides.
