The rhizome and tops of Polypodium vulgare, Linné.
COMMON NAMES: Common polypody, Rock polypod, Fern-root, Rock-brake, Brakeroot, Female fern, etc.
Botanical Source.—Polypodium has a perennial, creeping, irregular, brown rhizome, with membranous scales extending to the caudex or base of the stipe. The fronds are 6 to 12 inches high, distiched, green, smooth, deeply pinnatifid, being divided into alternate segments, nearly to the mid-vein, which are linear., oblong, obtuse, crenulate, the upper ones gradually smaller, parallel, a little curved, about a quarter of an inch wide. The stipe is naked and smooth. The fruit is borne on the lower surface of the frond, in large, distinct, golden dots, sori, or capsules, without any indusium, round, in a double row, and becoming finally brownish (W.—Eaton).
History and Description.—Polypody is common on shady rocks, in woods, and mountains throughout the United States. The root and tops are used in medicine. The root is of some length, 2 to 4 lines in diameter, frequently crooked, with chaffy scales, which are readily removed, and having many delicate, knobby rootlets. It has a peculiar, rather unpleasant odor, and a saccharo-mucilaginous, somewhat sickening taste. Water extracts its properties. Its constituents, according to Hager (Handbuch der Pharm. Praxis), are fatty oil (about 8 per cent), resin, some tannin, mannit, dextrose, dextrin, starch, malic acid, and a sweet substance resembling glycyrrhizin.
Action, Medical Uses, and Dosage.—This plant is pectoral, demulcent, purgative, and anthelmintic. A decoction or syrup as been found very valuable in pulmonary and hepatic diseases, and a strong decoction is recommended as a purgative, and for the expulsion of taenia and other worms. Dose of the powdered plant, from 1 to 4 drachms; of the decoction or syrup, from 1 to 4 fluid ounces, 3 or 4 times a day.
Related Species.—Polypodium adiantiforme, a West Indian plant, is regarded by the natives as a pronounced antisyphilitic, and medical testimony seems to confirm its reputation in that direction. The Central American fern, Polypodium friedrichsthalianum, is said to possess like virtues, and to be a remedy against the bite of the Mexican insect, toboba (New Idea, 1885; from Dragendorff's Heilpflanzen).