Hypericum. Hypericum perforatum L. St. John's Wort. Millepertuis, Casse-diable, Fr. Johanniskraut, Hartheu, G. (Fam. Hypericaceae.)—A perennial herb, with a very acrid juice, naturalized from Europe and a pernicious weed in this country. It has a peculiar balsamic odor, which is rendered more sensible by rubbing or bruising the plant. Its taste is bitter, resinous, and somewhat astringent. It imparts a yellow color to cold water, and reddens alcohol and the fixed oils. Its chief constituents are volatile oil, a resinous substance, tannin, and coloring matter. This latter, known as hypericum red, is a reddish resin, smelling like the flowers, soluble in alcohol, ether, ethereal and hot fatty oils, coloring the solution from wine red to blood red. It is soluble in alkalies with green color, and gives yellow precipitates with the alkaline earths and metallic salts. As a medicine it was in high repute among the ancients and the earlier modern physicians. Among the complaints for which it was used were hysteria, mania, intermittent fever, dysentery, gravel, hemorrhages, pectoral complaints, worms, and jaundice; but it was, perhaps, most highly esteemed as a remedy in wounds and bruises, for which it was employed both internally and externally. It probably has somewhat analogous power to the turpentines. It formerly enjoyed great reputation for the cure of demoniacs, and the superstition still lingers among the vulgar in some countries. At present the plant is scarcely used except as a domestic remedy. The summits were given in the dose of two drachms or more. A preparation, oleum hyperici or red oil, made by macerating four ounces of the tops in a pint of olive oil, is still used in many families for bruises.
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.