POIyYGONUM. 



Nut solitary, either triangular or compressed, pointed. Embryo 

 enveloped in farinaceous albumen. 



747. P. Hydropiper Linn. sp. pi' 51 7. Eng. Bot. t. 989. FL 

 Lond. t. 26. Eng. Fl. ii. 235. Common in ditches and watery 

 places. 



Root fibrous, whorled, as in most of the genus. Herb smooth. Stem 

 erect, 2 feet high, branched, round, more or less red and shining, swelled 

 above each joint. Leaves lanceolate, undulated, stalked, pale shining 

 green, without spots. Stipules fringed with unequal bristles, very 

 obscurely ribbed. Clusters terminal, long and slender, curved, in- 

 terrupted, leafy in their lower part ; their partial flower-stalks erect, 

 close, accompanied by tubular, sheathing, abrupt, coloured bracteas. 

 Calyx 4- or 5-cleft, variegated with red, white and green, covered with 

 glandular dots, such as are scattered more or less universally, over the 

 whole herbage, and in which its acrid quality resides. Stamens 6, 

 rarely 8. Styles united nearly half way up. Stigmas capitate, often 

 red, sometimes 3. Fruit compressed, purplish black. Leaves so acrid 

 as to act as vesicants. It is reputed to be a powerful diuretic, but to 

 lose its activity by drying, on which account it requires to be used fresh. 

 Will dye wool yellow. 



748. P. Bistorta Linn. sp. pi. 516. Eng. Bot. t. 509. FL 

 Lond. t. 22. Woodv. t. 34. Eng. Fl. ii. 236. Pastures and 

 meadows, especially in the north. (Bistort.) 



Root creeping, fleshy, or rather woody, often bent or zigzag, power- 

 fully astringent. Stems solitary, simple, erect, straight, leafy, 1^ or 2 

 feet high, round, striated, smooth. Leaves smooth, ovate, wavy, blunt- 

 ish, glaucous beneath; radical ones somewhat heart-shaped, and 

 nevertheless decurrent, making a narrow wing to their footstalks. 

 Footstalks of the stem-leaves tubular and sheathing, each crowned 

 with a membranous jagged stipula. Cluster terminal, leafless, erect, 

 cylindrical, dense, many-flowered, interspersed with membranous, 

 notched, brown, bracteas. Partial stalks simple, very slender. Calyx 

 rose-coloured, deeply 5-cleft, obtuse, spreading. Stamens 8, longer 

 than the calyx. Styles quite distinct, with small obtuse stigmas. Fruit 

 triangular, black and shining. Smith. A powerful astringent. The 

 decoction may be employed in gleet and leucorhoea, as an injection ; as 

 a gargle in relaxed sore throat and spongy gums, and as a lotion to 

 ulcers attended with excessive discharge. Internally it has been em- 

 ployed, combined with gentian, in intermittents. It may also be used 

 in passive haemorrhages and diarrhoea. Pereira. 



749. P. aviculare Linn. sp. 519. Eng. Bot. 1. 1252. Fl. Lond. 

 t. 27. Eng. Fl. ii. 238. Common every where in sandy waste 

 places, hard beaten gravel walks, &c. (Knot grass.) 



Root fibrous, long, very tough, and somewhat woody, branched 

 below, simple at the crown. Stems several, spreading in every direc- 

 tion, generally prostrate, much branched, round, striated, leafy at the 

 numerous knots or joints. Leaves alternate, stalked, hardly an inch 

 long, elliptic or lanceolate, entire, obtuse, single-ribbed, smooth except 

 at the margin, tapering at the base, very variable in width; their sub- 

 361 



