This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Cetraria. - Synonym. - Iceland Moss. Cetraria islandica (Linne). Acharius (class Lichenes).
From 5 to 10 cm. long, foliaceous, irregularly branched into fringed and channelled lobes, brownish above, whitish beneath, and marked with small, depressed spots; brittle and inodorous; when softened in water, cartilaginous, and having a slight odor; its taste is mucilaginous and bitter.
The chief constituents are - (1) Lichenin, C12H20O10, 70 per cent (2) Cetraric Acid, C18H16O8, a bitter principle, 2 per cent. (3)
Lichenstearic Acid, C14H34O3 1 per cent. (4) Fumaric Acid. (5) Oxalic Acid.
Pine leaves, mosses and other lichens.
Cetraria, 50. By boiling in water and straining to 1000. Dose, 1 to 4 fl. oz.: 30. to 120. c.c.
The decoction is demulcent, and may be given in sore throat. The moss is a food, and the jelly formed by boiling may, when suitably flavored, be taken by diabetics.