Small stands of ephemeral vegetation with an often open cover of annuals and short-lived perennials occur patchily on British salt-marshes. Recurrent assemblages are rare and there seems to be a large element of chance in the floristic composition, early arrivals frequently preempting the niche. Such vegetation may include Sagina maritima, S. nodosa and Plantago coronopus, more rarely Bupleurum tenuissimum (to the south-east) and Centaurium littorale (to the north) and provide a salt-marsh context for ephemerals such as Cochlearia danica and Desmazeria marina which also occur in other maritime habitats.

Breaks in the turf of mid-and upper-marsh communities provide the most usual habitat for such species and they are especially characteristic of old turf-cuttings where they form part of the sequence of recolonising vegetation giving way to mixtures of Festuca rubra, Agrostis stolonifera, Puccinellia maritima and Potentilla anserina, which come to approximate to the Puccinellietum maritimae, the Juncetum gerardi or the Festuca-Agrostis-Potentilla mesotrophic grassland. Such ephemerals also occur in disturbed situations around reclamation banks (e.g. Gray 1977, 1979, Adam & Akeroyd 1978).

This kind of vegetation is the nearest equivalent in Britain to similarly diverse assemblages on Continental salt-marshes which have been assigned to the Saginion alliance in the Saginetea maritimae Westhoff, van Leeuwen & Adriani 1962 (e.g. Beeftink 1962, 1965, 1975, 1977a; Tüxen & Westhoff 1963; Westhodd & den Held 1969).