Slender annual or perennial to 1 m, simple or branched, erect or ascending; lvs narrowly lanceolate or elliptic, glabrous, to 20 נ2 cm; ocreae glabrous or strigose; racemes slender, erect or arched, to 10 cm, much interrupted, especially below, where the internodes may be 2-3 cm; fls greenish; tep 5, 2 mm; pedicels exsert 1-2 mm at maturity; achenes smooth and shining, lenticular or trigonous, 2.4-3 mm, two-thirds as wide; 2n=44. Wet soil, open swamps, and shallow water; Que. to Fla., and w. to the Pacific; also in tropical Amer. (Persicaria p.; Polygonum acre) Two geographically coextensive vars. of doubtful significance:
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.