Usnea has a mossy look to it, but is actually a lichen- a fungus and an algae living in symbiosis as one organism. Its historical name, Old Man’s Beard, points both to its appearance and to its use, following the Doctrine of Signatures, as a tonic to the hair and scalp.
Usnea has also long been prized for its more common modern use as a strong anti-infective and antibiotic. It is especially active against bacteria such as Streptococcus, Staphylococcus, Tuberculosis, and other fast-growing bacteria.
It has very little effect on the beneficial bacteria of the digestive system, and so is gentler and has fewer side effects than pharmaceutical antibiotics, while still being more effective than penicillin in some cases. It also fights Trichomonas infection and other pathogens, such as yeasts and fungus, which commonly affect the female reproductive system.
Usnea is also commonly used against urinary tract infections and lupus. Its combination of antibiotic and immune-enhancing effects with its ability to relax smooth muscles, especially the bronchi, make it very valuable for colds, flu, pneumonia, bronchitis, tuberculosis, and related problems.
Read more about Usnea in this post.