Vegetation of Northern Cape Breton. . 367 



(toward the right in Fig. 44) that where the rock floor is 

 slightly inclined the layer of peat becomes thinner. Swamp C 

 differs from both swamps A and B in having originated in and 

 around a shallow, poorly drained pond, the extreme depth of 

 which was not ascertained. In its larger aspects, the vegetation 

 in both these swamps is similar to that of swamp A: the two 

 species of Scirpus and the Sphagna predominate, and various 

 species characteristic of both well-drained and undrained swamps 

 are represented. But the still more boggy nature of the habitat 

 is evidenced particularly by the frequency here of the ericaceous 

 shrubs, Chamaedaphne calyculata and Ledum grocnlandiciim, 

 neither of which occur in swamp A. The relatively xerophytic 

 nature of the habitat is further suggested by the presence of 

 Pteris aquilina and Jtmiperus communis depressa. 



The following list of species characteristic of one or all of the 

 Broadcove Mountain swamps, but mostly not heretofore men- 

 tioned in any connection, is of interest. 



Selaginella selaginoidcs Spiranthes Rofnanzoffiana 



Larix laricina Potentilla fruticosa 



Muhlenbergia racemosa Viola conspersa 



Eriophorum tenellum Conioselinum chinense 



Eriophorum viride-carinatum Solidago rugosa 



Carex Michauxiana Solidago uUginosa 



Car ex oligosperma Cirsium muticum 



General observations. — In general, bogginess seems to be 

 correlated with poor drainage ; and this may be either occasioned 

 by the nature of the terrain or brought about through the 

 influence of vegetation. Topography favors the development of 

 boggy swamps where the surface is flat, fairly level, and so 

 situated that the ground becomes covered with a thin sheet 

 of water in wet weather. Boggy swamps are frequently 

 encountered, for example, on low, flat areas, bordering lakes and 

 ponds, which are subject to periodic inundation (see in this con- 

 nection p. 419). A heavy soil which dries out slowly favors the 

 development of boggy swamps. But many of the tracts, which 

 in northern Cape Breton are occupied by swamps of this type, in 

 a warmer, less humid climate would be merely periodic swamps 

 of the ordinary, well-drained type. The general prevalence here 



