Formations of annual pioneers occupying sands subject to variable salinity and humidity, on the coasts, in the dunal systems and in the saltmarshes of the Atlantic, the North Sea and the Baltic. They are usually limited to small surfaces and best developed in the zone of contact between dune and saltmarsh. Characteristic species include Sagina maritima, Sagina nodosa, Cochlearia danica, Gentiana uliginosa, Centaurium littorale, Bupleurum tenuissimum.