The Physiomedical Dispensatory by William Cook, M.D., 1869
Description: Natural Order, Lichenaceae. This lichen is a native especially of Iceland, but also of Northern Europe and America. It is a membranous perennial; thallus erect, leaf-like, three to four inches high, tufted and divided, varying in color from olive-brown to red-brown, tough, fringed along the edges, stiff and crisp when dry. Found in dry mountainous districts.
Properties and Uses: More attention has probably been paid to this lichen than it really deserves. An ounce of it, washed and picked, may be boiled for fifteen minutes in a pint and a half of water, and then strained. It yields a starchy mucilage, which will gelatinize if concentrated. This is demulcent and nutritious, and is not undeserving of some attention in chronic catarrh, dysentery, and diarrhea. It contains a little bitter principle, which is supposed to make it slightly tonic; but renewed applications of moderate heat seem to destroy this. Boiled in milk and seasoned with lemon and spices, it is often valued as an article of diet in phthisis, and recovery from prostrating maladies.
Medical Herbalism journal and medherb.com