Het Myriophyllo verticillati — Nupharetum bij Denekamp

Myriophyllum verticillatum and Nuphar lutea were observed growing together in the Almelo- Nordhorn Canal near Denekamp (Prov. Overijssel) together with among others the rare Utricularia neglecta. The composition of the aquatic vegetation found in this canal strongly corresponds with that of the Myriophyllo-Nupharetum described by OBERDORFER (1957). The occurrence of this association, as interpreted by the author, is in contradiction to the findings of WESTHOFF & DEN HELD (1969), who state that the association is lacking in the Netherlands. However, it is possible that in the Netherlands the association is restricted to this described locality. The author suggests to add Utricularia neglecta to the characteristic species of the Parvopotamion alliance and to consider U. neglecta and M. verticillatum as the two differentiating taxa of the Myriophyllo-Nupharetum.