Knot-grass: A genus of the trigynia order, belonging to the octandria class of plants; and in the natural method ranking under the 12th order, Holocaeae. There is no calyx; the corolla is quintuplicate, and calycine, or serving instead of a calyx; there is one angulated seed. There are 27 species; but the most remarkable are, 1. The bistorta, bistort, or greater flakeweed, hath a thick oblique intorted root, blackish without, and red within; a simple, round, slender stem, near two feet high; oval leaves, having decurrent footstalks, and the stalk terminated by thick short spikes of whitish-red flowers. 2. The viviparum, or smaller bistort, hath a thickish root, a simple slender stem half a foot high, spear-shaped leaves, and the stalks and branches terminated by long spikes of whitish-red flowers. Both these perennial flowers in May and June, succeeded by ripe seeds in August. They grow wild in England, &c. the first in moist, the other in mountainous situations. 3. Oriental polygonum, commonly called persicaria, hath fibrous roots; an upright, robust, strong, jointed stem, rising eight or ten feet high, dividing at top into several branches; very large oval-lanceolate alternate leaves, on broad footstalks half surrounding the stem; and all the branches terminated by long, slender, hanging spikes of reddish-purple heptandrous and digynous flowers, from July till October. 4. Fagopyrum, buckwheat, or branck, rises with an upright, smooth, branchy stem, from about a foot and a half to a yard high, heart-shaped fagittated leaves, and the branches terminated by clusters of whitish flowers, succeeded by large angular seeds; excellent for feeding pigeons and most sorts of poultry.

All these plants are hardy, and succeed in almost any soil and situation; the two first are perennial in root; and the third and fourth are annual, wholly decay at the end of summer, or early in winter. The first two sorts are retained in some curious gardens for variety; but their chief merit is for medical purposes; they are powerful astringents, and are used both internally and externally; esteemed very efficacious in hemorrhages and other fluxes; and good to heal sore mouths. The third sort, Oriental polygonum, or persicaria, is a most elegant elegant annual for the embellishment of pleasure-ground; assuming a majestic tree-like growth by its erect luxuriant stem, and branchy head; which being garnished with noble large foliage, and numerous pendulous spikes of flowers, in constant succession three or four months, exhibits a very ornamental appearance from June or July until October, and is easy of culture; that from its scattered seeds in autumn, young plants rise spontaneously in abundance the ensuing spring, and shoot up so rapidly as to attain six or eight feet in height by July, when they generally begin flowering, and continue till attacked by the frosts, when they totally perish; so that a fresh supply must be raised from seed annually. The fourth sort (buck-wheat) is a sort of corn, and is frequently cultivated both by way of fodder, cutting its stalks while young and green to feed cattle, and for its grain to feed pigeons, poultry, hogs, &c. It flourishes in any soil and situation, but generally thrives best in a light dry earth; and the drifted seeds seldom retard its growth. The first and second sorts are easily propagated in plenty, by parting the roots in autumn. The third sort, Oriental polygonum, being annual, is always propagated from seed annually, either in the full ground, or by means of hotbeds.

Uses. The root of a kind of bistort, according to Gmelin, is used in Siberia for ordinary food. This species is by Haller called *biflora foliis ad oram nervosis*, and by some other botanists *biflora montana minor*. The natives call it *mooska*; and so indolent are they, that, to save themselves the trouble of digging it out of the earth, they go in spring and pillage the holes of the mountain rats, which they find filled with these roots. In our country, bistort is used as a medicine. All the parts of bistort have a rough astringent taste, particularly the root, which is one of the strongest of the vegetable astringents. It is employed in all kinds of moderate hemorrhages and other fluxes, both internally and externally, where astringency is the only indication. It is certainly a very powerful styptic, and is to be looked on simply as such; the sudorific, antipellitential, and other like virtues ascribed to it, it has no other claim to than in consequence of its astringency, and of the antiseptic power which it has in common with other vegetable styptics. The largest dose of the root in powder is a single dram.