POLYGONUM. OCTANDRIA. TRIGYNIA. 407 



Perianth white or pale rose-colour; the 3 exterior leaflets 

 with a broad winged margin when in fruit. Mtt large, acutely 

 triangular, black and shining. 

 Hab. In hedges and thickets. August. 



17. P. sagitlatum L^ : flowers octandrous, capitate; 

 styles 3-cleft; leaves sagittate; stem retrorsely aculeate. 

 JVi 1 1 d. Spec, II. p. 453. M ic h. FL I. ■p. 241. Purs k 

 FLU p. 212. Big. Bost.]).d4. Elliott Sk.h p. A5S, 

 Walt. Car. p. 132. Helxine caule aculeate, foliis sagitta- 

 tis. Gron. Virg. Q4. Cold. Noveb. d2. Pluk. AmaL 

 t. 398. f. 5. 



Root annual. Stem long, slender, prostrate, or supported by 

 other plants, acutely quadrangular ; the angles armed with 

 minute reflexed prickles. Leaves an inch and a half in length, 

 and half an inch broad, acute ; the midrib and petioles acule- 

 ate. Stipules acute, lacerate at the tip. Flowers in small ter- 

 minal pedunculate heads. Perianth white. J^ut triangular, 

 black and shining ; the sides a little convex. 



Hab. In wet hedges and thickets. July — August. 



18. P. arifolium L, : flowers hexandrous, distinct ; styles 

 bifid ; spikes few-flowered ; leaves hastate ; stem retrorsely 

 aculeate. W i U d. Sptc. Ii.>. 453. Mich. Fl.U.p, 

 241. Pursh Fl.l.p.'212. B i g. Bost. p. 94. Elliott 

 S/c.\.p.45d. Walt. Car. T^. 132. P luk. Amal. 87. U 

 398. f. 3. 



Boot annual. Stem slender, very long, prostrate, or supported by 

 other plants, acutely angular; the angles armed with minute 

 prickles, which are much more remote than in the preceding 

 species. Leaves on long aculeate petioles, exactly hastate, 

 3 — 4 inches long, acuminate, with short scattered hairs on the 

 upper surface, minutely papillose beneath. Sti/ndes long, 

 smooth, obtuse, slightly ciliate. S/iifres 4 — 6-flowered ; Jlowerf! 

 remote. Perianth pale rose-colour, mostly 4-parted. 



Hab. In wet thickets. July — September, 



