Marsilea quadrifolia L. (Klaverbladvaren) nieuw voor Nederland

In 1998 Marsilea quadrifolia was observed for the first time in the Netherlands, on the bank of a sheet of water in a foreland of the river Waal, 190 km north of its nearest (former) localities, in a pioneer vegetation belonging to the association Eleocharito acicularis-Limoselletum, resembling its past occurrence in similar plant communities in Hungarian rice fields and in the Upper Rhine Valley. Two of the three specimens produced 20 sporocarps altogether. The new appearance of a European Red List species in the Dutch riverine area might be termed a striking and encouraging phenomenon which was made possible by a new kind of water and nature management.