4() memoirs from the department of botany of columbia college. 



[Plate 7.] 

 7. Polygonum amphibium Linnaeus. 



Polygonum amphibium Linnseus, 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. S, 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 amphihium, 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 coccineum var. aquaticum Pursh, FL Am. Sept. 271 (1814). 



Polygonum fluitans Eaton, Man. 274 (1817); Eaton & Wright, N. A. Bot. Ed. 8, 

 368. 



Polygonum amphibium Yar. 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 cm. broad, thickish and somewhat coriaceous, glossy above, obtuse or sub- 

 acute at the apex, shghtly unsymmetrical, rounded or narrowed at the base, ciliate or 

 eciliate ; petioles almost wanting or sonietimes 6 cm. long ; ocreae cylindric, those of the 

 stem 1.5-2.5 cm. long, those of the branches exceeding the internodes, truncate or rarely 

 with a spreading rim at the summit, nearly ecihate or fringed with a few bristles ; inflor- 

 escence consisting of a single terminal spicate raceme ; raceme oblong, ovoid or conic, 1-3 

 cm. long, erect, very dense ; ocreolae funnel-form, 2-3 mm. long, membranous, very thin ; 

 pedicel 1.5-2 mm. long; calyx Kght rose-colored, 4.5 mm. long, five-parted to below the 



