CLASS Till. ORDER II. J POLYGONUM. 575 



Habitat. Gravelly watery places ; about London, Norwich, in 

 Worcestershire, Cheshire, aiid Lancashire ; near Forfar, Scotland ; 

 near Cork, on the shore of Ballyowan Lake, and Castle Blauey Lake, 

 near Churchhill, side of the Baun, below Coleraine, Ireland. 



Annual ; flowering in September. 



Nearly allied to P. Hydropiper, but is of more slender habit, with 

 creeping underground stems, narrower leaves, and undivided styles. 



*** AVICULARE. Meisn. Flowers in axillary fascicles, or formed 

 into leafy interrupted spikes at the end of the branches. Styles 

 three, very short, and stigmas very small. 



9. P. avicula'ie, Linn. (Fig. 655.) Knot grass. Flowers axillary ; 

 leaves elliptic-lanceolate, rough on the margins, flat ; stipules short, 

 six ribbed, bifid, at length much divided ; stem herbaceous, much 

 branched ; fruit shorter than the perianth, striated, with raised points ; 

 root annual. 



English Botany, t. 1252. English Flora, vol. ii. p. 238. Hooker, 

 British Flora, vol. i. p. 185. Lindley, Synopsis, p. 212. 



Root stout, twisted, fibrous, somewhat woody, branched. Stems 

 mostly several aud prostrate, rarely erect, round, smooth, striated, with 

 numerous joints, from one and half to two inches apart, leafy and 

 branched from almost every joint, very variable in length and luxu- 

 riance, flexuous, smooth and shining, or glaucous, often of a purplish 

 colour. Leaves alternate, flat, with a rough somewhat creuated margin, 

 elevated on a short footstalk, the mid-rib and lateral veins slender, 

 green above, and glaucous beneath, or glaucous on both sides, smooth, 

 elliptic-lanceolate, obtuse, or acutely pointed, very variable in width 

 and length, rarely more than an inch long. Stipules at the base of the 

 leaves, at first tubular, and cleft into two lanceolate segments, brown, 

 with six elevated ribs at the base, the margin broad, pale, thin, mem- 

 branous, becoming much torn into very narrow shreds. Inflorescence 

 axillary clusters, of from two to four Jlowers, small, white, tinged with 

 pink or green, sessile, and elevated on short slender simple stalks. 

 Perianth divided about half way down into four or five oblong obtuse 

 segments. Stamens eight or ten, the filaments about half as long as 

 the perianth, dilated at the base, the anthers yellow, roundish, flat. 

 Styles short, three, spreading, with small obtuse stigmas. Fruit 

 shorter than the perianth, acutely triangular, pointed with the base of 

 the styles, broad, an opaque brownish black colour, rough, with close 

 lines of elevated points, closely enveloped in the persistent perianth. 



Habitat. Waste places, road sides, &c.; very common. 



Annual ; flowering all summer. 



This is an extremely common and variable plant in the size and 

 shape of its leaves, from the circumstance of its growing in such 

 various situations ; and like all other of our common plants it is most 

 useful not only in clothing waste places, and fringing the road sides 



