;}(54- Proceedings Portland Society Natural History 



arctic flora in this region has been discussed in an earlier 

 paper (15), and it will be sufficient here merely to enumer- 

 ate the more characteristic forms : 



Juniperus horizontalis Sedum roseum 



Elymus arenarius var. Empetrum nigrum 



villosus Coelopleurum actaeifolium 



Carex salina var. Vaccmium Vitis-Idaea var. 



kattcgatensis minus 



Carex maritima Mertensia maritima 



Iris setosa var. canadensis 



Association-types of sea bluffs in uncompacted rocks 

 Where wave action is cutting away a deposit of clay or 

 glacial till, bluffs result which differ materially in their veg- 

 etative covering from the rocky bluffs described above. As 

 long as the process of erosion is still active no plants can 

 grow on the face of these bluffs. The only vegetation 

 which appears is at the base and consists of a miscellaneous 

 aggregation of "slump plants", which have slid down from 

 the crest, together with various annuals, notable among 

 which may be cited Cirsium arvense, Oenothera muricata, 

 Senecio sylvaticus and Erigeron canadensis. When for 

 some reason erosion ceases, grasses and alders rapidly in- 

 vade the surface of the bluff and the latter spread with 

 amazing swiftness, forming in a comparatively shoi't time a 

 dense thicket. Associated with Alnus crispa var. mollis, 

 which is the alder commonly present in such places, are 

 various of the herbaceous plants to be cited later (page 372) 

 as characteristic of the moist edge of beaches. In some 

 cases spruces and birches are invading the alders and even- 

 tually a coniferous forest will occupy the area. 



The shore at the foot of these bluffs consists of a narrow 

 rocky strip of boulders and cobbles, showing gradations to 

 a shingle or a gravel beach. Unlike the latter, in this case 

 the beach is the result of erosion and not deposition. The 

 littoral zone, lying between the tide levels, is also covered 



