Succession ai< Relations of Vegetation. 273 



merged meadow.. Zostera marina is the dominant plant. 

 Melosira and Ceramium rubrum are the principal algal asso- 

 ciates. These are not nearly so abundant as in the harbors 

 farther south. Consequently the eel-grass washed ashore is 

 dean and when dried forms a valuable packing material. 



The Lowei Beach (Fig. 1) is the zone between low tide ancj 

 the upper limit of the summer waves. As elsewhere along the 

 coast, from the standpoint of vegetation it is sharply divided 

 into two sub-zones. These are most distinct on the rocky ex- 

 posures, Here the lower sub-zone extends about two meters 

 vertically on the cliffs and is occupied by a dense growth of rock- 

 weeds — -the Fucus-Ascophyllum Formation. The principal 

 species noted were Fucus vesiculosus, F. furcatus and Asco- 

 phyllum nodosum. Associated with them, but quantitatively 

 insignificant, are Polysiphonia fastigiata, Ulva lactuca lanceolata, 

 Chordaria flagelliformis, Cystoclonium purpurascens, Clado- 

 phora sp., Chondrus crispus and Rhodymenia palmata. 



Above, the rocks are bare. Thus, on the exposed headlands 

 the marine succession terminates abruptly in the Fucus-Asco- 

 phyllum Formation. Since the principal physiographic process 

 here is erosion the battering down of the cliffs results in the de- 

 struction of the rockweeds and succession of the Laminaria 

 Formation* 



Within the harbors where rocks afford a foothold the 

 laminarias and rockweeds maintain their usual positions. As a 

 tule, howevei, such situations are areas of deposition and conse- 

 quently muddy shoals prevail. These are, for the most part, bare 

 of vegetation except for scattered specimens of Ulva lactuca 

 latissima and mud-inhabiting bluegreen algae— the Ulva For- 

 mation. The upper portion of the lower beach in such situations 

 favors the development of the Saltmarsh Formation. This is 

 inaugurated by the Spartina glabra association, in which Spar- 

 tina glabra alterniflora * is the dominant plant. Fucus, Asco- 

 phyllum, Cladophora, and various bluegreen algae are scattered 

 throughout. The Spartina is usually less than a half meter in 

 height. 



The Middle Beach is reached only by the storm waves of 

 the winter months. On the headlands it is free of vegetation and 



• Nomenclature of higher plants follows Gray's New Manual of Botany, 7th edition, 1908. 



