It is the name of a genus of lichens of the family Parmeliaceae, They are similar to goatee beards or gray hair. It has medicinal uses, because from them you can extract the uric acid which is a strong antibiotic.
Usnea : Genus of lichens eladoniaceous, whose species are characterized by having the thae upright, sufruticosand and, as adult, pendant and filamentous, with the cortical layer somewhat separated from the medular.