Botanical Source.—This is a perennial plant, with simple, stout, erect, jointed, and hollow stems, marked with from 14 to 26 longitudinal furrows, the ridges rough with 2 rows of minute tubercles, growing from 2 to 3 feet in height, each stem bearing a terminal, ovoid spike. Frequently 2 or more stems are united at the base from the same root. The sheaths are from 2 to 3 lines long, from an inch to an inch and a half apart, ashy-white, black at the base and summit, short, with subulate, black, awned, deciduous teeth, which leave a bluntly crenate margin. The fertile plants are mostly leafless. The fruit is placed under peltate polygons, being pileus-like bodies, arranged in whorls, forming a spike-like raceme, from 4 to 7 spiral filaments surround the spores, which resemble green globules, and which roll up closely around them when moist, and uncoil when dry (G.—W.).
History and Chemical Composition.—This plant is common to the northern and western parts of the United States, growing in wet grounds, on river banks, and borders of woods, and maturing in June and July. Together with other Cryptogamia, this species abounds in the fossil remains of coal measures, indicating that they were once of gigantic dimensions, and formed a large part of the original flora of our globe. Silica enters largely into the composition of these plants, on which account they have been used to scour, rough, polish, etc.; 1.4 per cent of a brownish-green, semi-fluid fixed oil, easily saponifiable, was abstracted from this plant by F. J. Young, by means of petroleum benzin (Amer. Jour. Pharm., 1886, p. 420). The plant left 18.2 per cent of ash, and proved to be free from tannin, alkaloid, or glucosid. Mucilage, sugar, and a soft, green resin were shown to be present. The equisetic acid of Braconnot was found by Regnault to be identical with aconitic acid. The whole plant is medicinal, and imparts its properties to water.
Action, Medical Uses, and Dosage.—Diuretic and astringent. An infusion (℥ij to aqua Oj) drank freely, has been found beneficial in dropsy, suppression of urine, hematuria, gravel, and nephritic affections; and has also been used with advantage in gonorrhoea and gleet. This drug has a specific action in irritation the bladder, and in dysuria with tenesmic urging, in the nocturnal urinal incontinence of children, and in urinal incontinence, the effect of cystic irritation, it is a very serviceable remedy. The infusion or the decoction of the green stalks is preferred. The ashes of the plant are very valuable in dyspepsia connected with obstinate acidity of the stomach, and may be given alone, or combined with powdered rosin, or hydrochlorate of berberine, etc. Dose of the pulverized ashes from 3 to 10 grains, to be repeated 3 or 4 times daily. The fresh juice may be given in 1 or 2 ounce doses, administered in water. Specific equisetum, 5 to 60 drops.
Specific Indications and Uses.—Cystic irritation; nocturnal urinal incontinence; tenesmic urging to urinate; dropsy; renal calculi.
Equisetum arvense, Linné; Common horse-tail.—Canada to Kentucky and Virginia. This species puts forth its sterile stems after the appearance of the fertile ones. It has the medicinal uses of Scouring rush.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.