Myriophyllum heterophyllum in Belgium and in the Netherlands
In Belgium, Myriophyllum heterophyllum (Haloragaceae, EPPO Alert List) was first recorded in 1993 and isolated populations are still occurring in freshwater habitats in the Kempen region (Limburg province).
In the Netherlands, M. heterophyllum was first recorded in 1997-1999 in a gravel pit (now transformed into a fish pond) near Arcen (Limburg). According to Bruinsma (2009), the species was initially recorded in canals in the Brabant and Limburg regions and is suspected to have arrived via the Meuse river (originating in France and flowing through Belgium and the Netherlands before draining into the North Sea). M. heterophyllum is now commonly found in the Netherlands in North Brabant, Utrecht, Gelderland, Drenthe and Groningen. A distribution map of M. heterophyllum in the Netherlands is available in the Q-Bank database.
In both countries, the species is exhibiting a high spread potential, and forms dense populations.
Sources
Johan van Valkenburg, Plant Protection Service of the Netherlands, E-mail: j.l.c.h.van.valkenburg@minlnv.nl
Van der Meijden R, Holverda W J ; Duistermaat H (1999) Nieuwe vondsten en zaldzame planten 1997, 1998 en 1999 [New records of rare plants in 1997, 1998 and 1999]. Gorteria 25, 117-136.
Bruinsma J (2009) Myriophyllum heterophyllum. Werkgroep Aquatische Planten. 3 pp.
Invasive Species in Belgium (2011) Myriophyllum heterophyllum. http://ias.biodiversity.be/species/show/117
Q-Bank Invasive Plants in the Netherlands (2011) Myriophyllum heterophyllum. http://www.q-bank.eu/Plants/BioloMICS.aspx?Table=Plants