40 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE, 
[Puate 7. ] 
7. Polygonum amphibium Linnaeus. 
(>) 27 
Polygonum amphibium Linneus, Sp. Pl. 361 (1753); Gmelin, Syst. Nat. 2: 637; 
Willdenow, Sp. Pl. 2: 443; Michaux, Fl. Bor. Am. 1: 240; Persoon, Syn. 1: 440; 
Sprengel, Syst. 2: 259; Meisner, Monog. 67, in DC. Prodr. 14: 115; Torrey, Fl. 1: 403, 
Comp. 172; Beck, Bot. 301: Hooker, Fl. Bor. Am. 2: 131; Eaton & Wright, N. A. Bot. 
Ed. 8, 368; A. Gray, Man. 388; Wood, Cl. Bk. Ed. 41, 475, Am. Bot. & Fl. 283; S. Wat- 
son, Bot. Calif. 2: 13; Coulter, Man. Bot. Rocky Mt. Reg. 320; Greene, Fl. Francis. 
137, Man. Bay Reg. Bot. 42. 
Polygonum amphibium var. natans Michaux, Fl. Bor. Am. 1: 240 (1803) ; Meisner, 
Monog. 67, in DC. Prodr. 14: 115. 
Polygonum coccineum Muhlenberg, Cat. 40 (1813); Willdenow, Enum. Hort. Berol. 
1: 429 (1809); Pursh, Fl. Am. Sept. 271; Eaton, Man. 371; Barton, Comp. Fl. Phila. 
188; Sprengel, Syst. 2: 259; Eaton & Wright, N. A. Bot. Ed. 8, 368; Wood, Cl. Bk. 
Ed. 41, 475. 
Polygonum coccinewm var. aquaticum Pursh, Fl. Am. Sept. 271 (1814). 
Polygonum fluitans Eaton, Man. 274 (1817); Eaton & Wright, N. A. Bot. Ed. 8, 
368. 
Polygonum amphibium var. aquaticum Torrey, Fl. 1: 404 (1824), Comp. 172; Beck, 
Bot. 301; A. Gray, Man. 388. 
Polygonum amphibium var. fluitans Wood, Cl. Bk. Ed. 41, 475 (1855). 
Perennial, glabrous when mature, young shoots often pubescent. Stem immersed or 
floating on the surface of the water and rooting in the mud, 6-60 dm. long, branches 
usually arising from the rooting nodes; leaves oblong, elliptic or elliptic-lanceolate, 3-11 
em. long. 5-5 em. broad, thickish and somewhat coriaceous, glossy above, obtuse or sub- 
acute at the apex, slightly unsymmetrical, rounded or narrowed at the base, ciliate or 
eciliate; petioles almost wanting or sometimes 6 cm. long; ocreae cylindric, those of the 
stem 1.5-2.5 em. long, those of the branches exceeding the internodes, truncate or rarely 
with a spreading rim at the summit, nearly eciliate or fringed with a few bristles; inflor- 
escence consisting of a single terminal spicate raceme; raceme oblong, ovoid or conic, 1-3 
em. long, erect, very dense; ocreolae funnel-form, 2-3 mm. long, membranous, very thin ; 
pedicel 1.5-2 mm. long; calyx light rose-colored, 4.5 mm. long, five-parted to below the 
