Polygonum punctatum is a perennial or annual herb, to 1 m tall; slender, habit very variable.
Leaves alternate, lance-shaped to 20 long, 2 cm wide, sheaths (ocrea) bristle fringed.
Flowers greenish-white, 5-parted, petals (tepals) with minute dots (use hand lens); inflorescence slender, to 10 cm long, interrupted, especially towards base, internodes to 3 cm).
Fruit dry, achenes, lens-shaped or 3-sided; seeds eaten by some waterfowl and muskrats (Martin et al 1951).
Wetland status: OBL.
Frequency in NYC: Infrequent.
Habitat: Open, wet soil, swamps, swamp forest gaps; soil pH 6-8.7 Intolerant of shade, moderately tolerant of salt (USDA, NRCS 2010).