Zaaiproeven met de kustplanten Centaurium littorale (Turner) Gilmour en Blackstonia perfoliata (L.) Hudson subsp. serotina (Koch ex Reichenb.) Vollmann in het binnenland

C. littorale is distributed along the coast of Northwest Europe and in Central Europe. In the western part of its distribution area it occurs in young dune slacks and on protected beach plains; in the eastern part it is found on various saline soils. According to its distribution C. littorale may be regarded as a halophyte. B. perfoliata subsp. serotina is found in a coastal area in the southwestern part of the Netherlands. The main part of its distribution area is in southern Europe. Both species were sown in three inland sites in the Netherlands. C. littorale germinated on alkaline sandy substrates, but not on acid heath subsoil. On the alkaline soils, this biennial species completed its life-cycle several times, but after about ten years the number of specimens decreased because of competition with other species. It became clear that the absence of the species in the inland can be partly explained by the low dispersal capacity. The behaviour of B. perfoliata resembled that of C. littorale.