Hill: Penobscot Vegetation 423 



tion of sediment in shallow places. Consequently these 

 marshes are much less frequent than on less rugged portions 

 of the Atlantic coast, and where they do occur they are 

 much less extensive. In this region they attain their best 

 development behind barrier-beaches and along the tidal riv- 

 ers on the western side of the Bay (Figure 4-8). 



As is the case elsewhere the first species to appear in the 

 building up of a salt marsh is the salt thatch (Spartina 

 alterniflora). This coarse grass lines the banks of the ti- 

 dal creeks in situations where it is submerged at every high 

 tide. Back from the edges of the creeks the surface of the 

 marsh is higher and there is a zone in which the salt meadow 

 grass (Spartina patens) predominates. Frequently this is 

 present in a pure stand, but in other cases the following 

 species may be associated with it : 



Triglochin maritima Limonium trichogonum 



Salicornia europaea Plantago decipiens 



Suaeda maritima Solidago sempervirens 



The shoreward edge of the marsh where the substratum 

 is still higher is characterized by a zone in which the black 

 grass ( J uncus Gerardi) is the chief species. Often in lo- 

 calities where the salinity is reduced this species may be re- 

 placed by J uncus balticus var. Utt oralis (Figure 49). In 

 this rush zone are found such forms as : 



Agrostis alba var. maritima Carex maritima 

 Puccinellia paupercula Juncus bufonius 



var. alaskana Atriplex patula var. 



Hordeum jubatum hastata 



Agropijron re pens Spergularia canadensis 



Scirpus nanus Ranunculus Cijmbalaria 



Scirpus campestris var. Potentilla pacific*/ 



paludosus 

 Of these species Scirpus campestris var. paludosus. Carex 

 maritima and Ranunculus Cijmbalaria occur in the wetter, 

 muddier places. 



