MAEITIME ASSOCIATIONS 283 



becomes a calluna-heath, or a heath dominated by Salix 

 repens. 



Dime -Marsh. In the hollows amongst the dunes 

 water collects, and a fresh-water marsh develops. It 

 differs in no important respect from an ordinary marsh, 

 except where the sea has access to it, when it is inter- 

 mediate in character between a fresh-water marsh and a 

 salt-marsh. 



3. Pebbly and Shingly Beaches. These differ from a 

 sandy beach chiefly in the greater abundance of inland 

 plants and the scarcity of grasses with underground 

 creeping rhizomes, which are so characteristic of sand. 



The following zones met with on some pebbly beaches 

 of the south coast of England may be taken as typical of 

 such beaches in general : 



Nearest the sea is a zone of Atriplex hastata. Behind 

 this a narrow zone of Rumex crispus, associated with 

 which are Glaucium luteum, Solatium Dulcamara var. 

 marinum (forming a mat close to the ground), Senecio 

 Jacobcea, and various species of Atriplex. Farther back 

 Ulex europceus is dominant, with Silene maritima very 

 abundant, and a few specimens of Galeopsis Ladanum var. 

 canescens. Between this zone and the Rumex-zone occur 

 many scattered plants of Beta maritima, Galium Mollugo, 

 Teucrium Scorodonia, and Silene maritima. Behind the 

 zone of Ulex the plants are again scattered. In addition 

 to the foregoing, Daucus Carota, EcJiium vulgar e, and 

 Leontodon hirtus occur. In places the Ulex-zone is absent, 

 the vegetation behind the Rumex - zone consisting of 

 scattered plants of Dianthus prolifer, Geranium Roberti- 

 anum var. purpureum, Glaucium luteum (very abundant), 

 Galium Aparine, and G. Mollugo, Matricaria inodora var. 

 salina, and Helminthia echioides. 



Where the beach is more sandy Eryngium maritimum 

 becomes dominant, and associated with this are Arenaria 

 peploides, Trifolium arvense, Crithmum maritimum, Silene 

 maritima, Spergularia marina, Beta maritima, Rumex 

 crispus, Senecio Jacobcea, Crambe maritima, and Daucus 

 Carota. 



All the inland plants or their varieties develop much 

 thicker, succulent leaves than when growing in their usual 

 habitat. 



4. Rocks and Cliffs. The vegetation of rocks which 



