HEUKELS-VAN OOSTSTROOM (1962) mentions that Ranunculus aquatilis subsp. peltatus occurs in the pleistocene part of the Netherlands. In 1966 the species was found some tens of kilometers west of the western border of the area, in the centre of the polderland near Bodegraven in a small natural stream of young-holocene origin (a geographical phenomenon). The habitat of the species is a small winding ditch containing shallow water with only periodical weak movement. The vegetation is strongly influenced by anthropozoogene factors. The species is not accompanied by the characteristic species of Callitricho-Batrachion except Hottonia palustris. In 1970 the species occurred in a few number of individuals as a probable consequence of an excessive development of Elodea nuttallii.