Vegetation of Northern Cape Breton. 319 



observed, such forests represent the culmination of hydrarch 

 rather than xerarch successional series, and they will therefore 

 be discussed later (p. 371), in connection with hydrarch succes- 

 sions. 



The average climax forest of sandy flood plains along swift 

 streams approximates closely the climatic climax forest-type of 

 the region, differing from this chiefly in the presence, or more 

 luxuriant development, of such species as Ulnius americana and 

 Fraxinus americana, among the trees, and of various herbaceous 

 plants, such as the following: 



Osmnnda Claytoniana Streptopus amplexifolius 



Polystichiim Braunii Thalictrnm polygamum 



Cinna latifolia Saniciila marilandica 



Trillium cernnum Osmorhiza divaricata 



Smilacina racemosa Pyrola asari folia 



Listera convallarioides Solidago latifolia . 



3. The Formation-types of Uplands along the Seacoast 



a. INTRODUCTORY 



Under this heading are included only those upland associations 

 which are peculiar to habitats in the immediate proximity of the 

 shore and whose ecological aspect is obviously correlated with 

 this fact. The character of vegetation along the seacoast is 

 influenced to a greater or less degree by wind, salt water, and 

 physiographic agencies. The plant associations are best classi- 

 fied with reference to physiographic factors, as (i) Associations 

 along Eroding Shores, and {2) Associations along Depositing 

 Shores. As eroding shores are classed the sea bluffs and head- 

 lands which form such a striking topographic feature along much 

 of the coastline. Depositing shores include the commonly 

 encountered shingle beaches and the less frequently encountered 

 sandy beaches and dunes. 



In addition to the figures that accompany the description which 

 follows, attention may be called in this connection to Figs. 3, 6, 

 8. 15, 33, 38,41. 



h. THE ASSOCIATION-COMPLEXES OF SEA BLUFFS AND HEADLANDS 



Association-types of rocky sea bluffs. — The application of the 

 term sea bluff is here restricted to the more or less precipitous 



