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Wetland Plants and Plant Communities of Minnesota and Wisconsin


(Polygonum amphibium L.)

Floating-leaved form of water smartweed
Terrestial form of water smartweed
Floating-leaved Form Terrestial Form



FIELD CHARACTERISTICS: A highly variable rhizomatous perennial herb with prostrate or erect stems to a length of 1-2 m. Several lance-shaped leaves occur along the elongate stems. This species is divided into two forms: an aquatic form with submergent and glabrous floating leaves 2-15 x 1-2 cm. (formerly known as P. natans) and a "terrestrial" form with erect, densely hairy leaves usually less than 4.5 cm. wide (formerly known as P. coccineum). The inflorescence is a usually solitary terminal spike of densely crowded pink flowers. The ocreae of at least the aquatic form exhibits a green flange at its summit.

ECOLOGICAL NOTES: Water smartweed occurs in lakes, permanent and ephemeral ponds, quiet backwater areas, river edges and marshes. The "terrestrial form" occurs typically in marshes and on shores.

SOURCE: Gleason and Cronquist (1991); Swink and Wilhelm (1994); Voss (1985).

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