This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Bistorta Pharm. Lond. & Edinb. Bis-torta major radice minus intorta C. B. Polygonum Bistorta Linn. Bistort or snakeweed: a plant with oval, pointed, wrinkled leaves, of a dark green colour above and bluish underneath, standing on long pedicles, and continued a little way down the pedicle, forming a narrow margin on each side: among these arise round, slender jointed, unbranched stalks, furnished with smaller and narrower leaves which have no pedicles; bearing on the top spikes of imperfect five-leaved red flowers, which are followed by triangular seeds. It is perennial, grows wild in moid meadows in several parts of England, and flowers in May and June.
The root of this plant is bent and jointed, commonly about the thickness of the finger, surrounded with bushy fibres, of a blackish brown colour on the outside, and reddish within: it is distinguished from the roots of the other bistorts, by being less bent; that of the officinal species having only one or two bendings, and those of the others three or more.
This root has a strong astringent taste, without any manifest smell or particular flavour. It is one of the strongest of the vegetable styp-tics, and frequently made use of as such, in disorders proceeding from a laxity and debility of the solids, for restraining alvine fluxes, after due evacuations, and other preternatural dis-charges both serous and sanguineous. It has been somerimes given in intermitting fevers; and sometimes, also, in small doses, as a corroborant and antiseptic, in acute malignant and colliquative fevers; in which intentions, Peruvian bark has now deservedly superseded both this and all the other astringents.
The common dose of bistort root, in sub-stance, is fifteen or twenty grains: in urgent cases, it is extended to a dram. Its astringent matter is totally dissolved both by water and rectified spirit* (a); the root, after the action of a sufficient quantity of either menstruum, remaining insipid: the watery tinctures are of a dark brownish colour, the spirituous of a brownish red. On infpiffating the tinctures, the water and spirit arise unflavoured, leaving extracts of intense stypticity.