Wasser-Kn?terich, Persicaria amphibia, Synonym: Polygonum amphibium / Persicaria amphibia, syn. Polygonum amphibium is a species of flowering plant in the knotweed family known by several common names, including longroot smartweed, water knotweed, water smartweed, and amphibious bistort, Historisch, historical, digital improved reproduction of an original from the 19th century / digital restaurierte Reproduktion einer Originalvorlage aus dem 19. Jahrhundert, genaues Originaldatum nicht bekannt.