Over een duinvalleivegetatie met Kammos [Ctenidium molluscum (Hedw.) Mitt.], een nieuwe soort voor het Waddendistrict

In 1987 the moss Ctenidium molluscum was found at three sites in a small secondary dune-slack on the island of Texel. Outside the area of limestone grasslands in the south of Limburg this species is very rare in the Netherlands. The vegetation in which it was found is dominated by Schoenus nigricans and Juncus subnodulosus, while in the moss-layer Calliergonella cuspidata, Fissidens adianthoides and Campylium stellatum occur frequently. This vegetation can best be regarded as a fragmentary example of the Schoeno-Juncetum subnodulosi Allorge 1922, a community of calcareous mires. From 1982 onwards the vegetation is mown annually, under the influence of which it is still changing. Every year ‘new’ species can be recorded at the site. In the past two years amongst others Oenanthe lachenalii, Samolus valerandi and Taraxacum palustre were discovered as newcomers. In the Netherlands these species are mainly restricted to brackish areas near the sea-coast, like young dune-slacks and salt-marshes. Outside the Netherlands they may also be found in areas with purely fresh water, e.g. in the Schoeno-Juncetum subnodulosi. The same is true for Carex distans. It is suggested the occurrence of these plants (none of which is a true halophyte) in brackish environment should not be ascribed to the salt-content of the soil but to the fact that such brackish sites are also quite base-rich.