Nieuwe vondsten van Ceratophyllum submersum L. (Fijn hoornblad) in de Maas en de IJsselvallei; uitbreiding als gevolg van klimaatverandering?

New records of Ceratophyllum submersum L. in the River ‘Meuse’ and in the ‘IJssel Valley’; an expansion caused by climate change? Inland records of Ceratophyllum submersum L. have always been rare in the Netherlands. Between 2009 and 2014 the authors have found the species in the valley of the River IJssel and twice in the River Meuse. Others have recently found the species in the eastern part of the Netherlands and in the east central floral district associated with the major rivers (‘Fluviatiel District’, F). The records suggest that C. submersum is extending its range to inland habitats, probably because of the higher winter temperatures in the last decade.