[Knotweeds and Smartweeds: The Genera Bistorta, Fallopia, Persicaria and Polygonum in the
Columbia River Gorge of Oregon and Washington]
Pink Knotweed, Water Smartweed
Persicaria amphibia
Synonyms: Polygonum amphibium, Polygonum amphibium var. coccineum, Polygonum amphibium var. emersum, Polygonum amphibium var. natans, Polygonum amphibium var. stipulaceum, Polygonum coccineum, Polygonum coccineum var. coccineum, Polygonum coccineum var. hartwrightii, Polygonum natans, Polygonum natans var. hartwrightii
The photo above shows a close-up of the inflorescence of pink knotweed as seen from the Columbia River shoreline at Dalton Point.........September 1, 2007. Note the short, gland-tipped hairs on the stem.
Characteristics:
Habitat:
Closeflowered knotweed may be found on mudflats or damp sandy areas in riparian zones along rivers, streams or lake and pond edges.
Range:
In the Columbia River Gorge, pink knotweed may be found along the shores of the Columbia River and its major tributaries between the Sandy River in the west and Horsethief Lake in the east.
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The photo above shows a close-up of pink knotweed as seen from the Columbia River shoreline at Dalton Point........September 1, 2007. Plants can be as much as 70 cm high. The photo at right shows pink knotweed as seen on the Columbia River shoreline at Dalton Point........September 28, 2015.
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Close-ups of water smartweed as seen along the boat ramp at Dalton Point, western Columbia River Gorge..........August 19, 2009.
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Water smartweed as seen in vernally moist meadows at Panakanic in western Klickitat County...........May 17, 2013.
A close-up of pink knotweed sprawling across the shoreline of the Deschutes River about one-half mile upstream of its mouth.........July 27, 2011.
Paul Slichter
