Usnea (Usnea barbata) isn't a plant at all, but actually it is a lichen, which is a combination of algae and fungi functioning as a single organism. Usnea grows on old trees in cool, damp forests, most commonly found in the pacific Northwest which provides most of the nations supply. Usnea is abundant throughout most parts of the Northwest and the various species of usnea are hard to distinguish, but have equivalent uses in herbal medicine.