This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Hair-cap Moss, Polytrichum juniperum, is diuretic in strong infusion of the whole plant, two ounces of the infusion being given every hour. Its use in dropsy seems to be justified; but pharmaceutical preparations are commonly disappointing. The fl. is given in 30- to 60-minim doses.