153. Polygonum Bistorta, Linn.—Great Bistort or Snake-Weed.
Sex. Syst. Octandria, Trigynia.
History.—It is doubtful by whom this plant is first mentioned. It was certainly noticed by the herbalists of the 16th century.
Botany. Gen. Char.—Calyx 4—5-cleft, more or less coloured. Stamens 5—8, in 2 rows, generally with glands at the base. Styles 2—3, more or less united at the base. Nut 1-seeded, lenticular or 3-cornered, inclosed by the calyx. Embryo lateral, incurved; cotyledons not contorted.
Sp. Char.—Stem simple. Leaves oblong-ovate, somewhat cordate and wavy; petioles winged. Spike dense, terminal.—Flowers flesh-coloured. Stem 1—1 ½ foot high.
Hab.—Indigenous. Meadows. Perennial. Flowers in June.
Description.—Bistort root (radix bistortae) is twice bent on itself—hence its name, from bis, twice; and torta, twisted or bent. It is rugous and brown externally; reddish internally; almost inodorous; it has an austere, strongly astringent taste.
Composition.—This root has not been analyzed. The principal constituents are tannic acid, starch, oxalate of lime, colouring matter, and woody fibre.
Physiological Effects.—The local effect is that of a powerful astringent, depending on the tannic acid which it contains; its remote effects are those of a tonic (see vol. i. p. 243). The presence of starch renders the root nutritive—hence in Siberia it is roasted and eaten.
Uses.—It is but little employed. A decoction of the root is sometimes employed as an astringent injection in leucorrhoea and gleet; as a gargle in spongy gums and relaxed sore-throat; and as a lotion to ulcers attended with a profuse discharge.
Internally it has been employed, in combination with gentian, in intermittents. It has also been used as an astringent in passive hemorrhages and chronic alvine fluxes.
Administration.—The dose of the powder is from ℈j to ʒss. The decoction (prepared by boiling ℥ij of the root in Ojss of boiling water) may be administered in doses of from f℥j to f℥ij.