Hygrophila polysperma found in thermal waters in Germany and in Poland
Hygrophila polysperma (Acanthaceae, EPPO Alert List) was found in 2007 in Germany in Nordrhein-Westfalen (Kasterer Mühlenerft) in the Erft thermal river, as well as in Lake Fülinger near Köln. The species was then found in 2008 in Poland in a farm fish pond near the Patnowskie Lake and Ślesiński Channel, which are part of the cooling system of power stations. H. polysperma is considered as casual in these thermal waters.
Gabka M ; Owsianny PM (2009) First records of the Hygrophila polysperma (Roxb.) T. Anderson (Acanthaceae) in Poland. Botanika-Steciana 13, 9-14.
Hussner A, Josephs M ; Schmitz U (2007) About Hygrophila polysperma (Roxb.) T. Anderson and Pontederia cordata in North Rhine-Westphalia. Floristische Rundbriefe 40, 25-30.
Hussner A (2005) Zur Verbreitung aquatischer Neophyten in der Erft (Nordrhein-Westfalen). Frankfurter Geobotanische Kolloquien 19, 55-58.