Catapodium marinum (L.) Hubbard, Scirpus planifolius Grimm en Trifolium micranthum Viv. op Goeree

The mediterranean-atlantic species Catapodium marinum (L.) Hubbard reaches its northern limit on the continent in the Netherlands. Up to 1959 only 2 localities on the Dutch coast were known. In 1961 the species was discovered in large quantities on the brackish estuary shore of the island of Goeree, by far the richest occurrence in the country. The habitat in the three Dutch localities is similar: low, sandy, dry, irregularly submersed dunes in the ecotone between xerosere and halosere, with fluctuating, but mostly low, salt content and rather high lime content; i.e. in the dry desalinated “Koelerion”-variant of the Saginetum maritimae. Scirpus planifolius Grimm, another ecotone species, is rather common in Britain, but much rarer on the continent, although it is not an atlantic or subatlantic plant. Here it is probably diminishing by reclamation of the suitable habitats. It is a characteristic species of the “disturbance ecotone”, the transition zone between some contrasting habitats: salt-fresh, dry-wet, rich in nutrients-poor in nutrients. In the island of Goeree it was observed in large quantities in moist dune valleys, as well in the salt-fresh transition zone as in the wet-dry one. Its ecology as a species of the alliance Agropyro-Rumicion crispi is discussed. Finally a new locality of the mediterranean-atlantic Trifolium micranthum Viv. is described. In the Netherlands this species was hitherto only known from a few localities. In the island of Goeree it was found in two spots in damp grazed valleys in the inner dunes poor in lime.