84 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 
[PuatEe 29.] 
29. Polygonum Hydropiper Linnaeus. 
Polygonum Hydropiper Linnaeus, Sp. Pl. 361 (1753); Ginelin, Syst. Nat. 2: 638 
Michaux, Fl. Bor. Am. 1: 238; Persoon, Syn. 1: 440; Muhlenberg, Cat. 40; Bigelow, 
Fl. Bost. 93; Meisner, Monog. 76 and in DC. Prodr. 14: 109; Hooker, Fl. Bor. Am. 2: 
132; Torrey, Fl. N. Y. 2: 150; A. Gray, Man. 387; Wood, Am. Bot. and Fl. 283; S. 
Watson, Bot. Calif. 2: 14; Coulter, Man. Bot. Rocky Mt. Reg. 320. 
Polygonum punctatum Torrey, Fl. N. Y. 2: 151 (1834), not Elliott. 
Annual, glabrous, usually bright green. Stem erect or assurgent, 2-6 dm. long, 
lax, simple or branched throughout, sometimes red or reddish; leaves varying from 
ovate to oblong-lanceolate sometimes lanceolate, 1.5-9 em. long, .8-2.3 em. broad, acute 
at both ends or often acuminate at the apex, ciliate, more or less papillose, undulate or 
slightly crisped, punctate, containing a very acrid juice; ocreae cylindric, .5-1 em. long, 
becoming somewhat funnelform and oblique, nearly glabrous, fringed with long bristles, 
usually enlarged about the bases, often bearing one or two flowers within; inflorescence 
paniculate, more or less compound, the ultimate divisions ending in spicate racemes; 
racemes linear, 2-6 cm. long, drooping, much interrupted; ocreolae funnelform, 1.5-2 
mim. long, slightly oblique, fringed with a few short bristles; pedicels slender, 2. mm. 
long; calyx greenish, 2.5-3 mm. long, three to five-parted, usually four-parted, the seg- 
ments rather narrowly oblong, mutate glandular; stamens four or sometimes six, 1n- 
cluded; style .5 mm. long, two or three-parted to near the base; achene lenticular, bicon- 
vex, slightly gibbous or triquetrous, 3 mm. long, broadly oblong or ovoid, sometimes 
orbicular or even broader than high, short-pointed, dark brown, strongly granular and dull. 
Canada to Florida and westward across the continent. Naturalized from Europe 
southward and eastward, said to be native in the north and west. 
