Vegetation of Northern Cape Breton. 335 



The association-types of fallozv fields. — For several years 

 after a plowed field has been abandoned its vegetation may 

 consist largely of weeds. Common species in such a habitat are : 



Riimex Acetosella Solidago graminifolia 



Spergula arvensis Achillea Millefolium 



Raphanus Raphanisintm Chrysanthemum LeiicantJiemum 



Prunella vulgaris Leontodon atitnmnalis 



Galeopsis Tetrahit Taraxacum officinale 



Plantago major Cirsium arvense 



In the early stages of reclamation, so long as the plants are 

 scattered and the vegetation relatively open, both annual and 

 perennial species may be about equally well represented. But 

 as the ground comes to be more densely populated, most of the 

 annuals are crowded out and the plant cover comes to consist 

 almost entirely of species which are perennial. Various grasses, 

 especially Danthonia spicata and Poa pratensis, appear rather 

 early in the succession, and as time goes on these come to com- 

 prise a more and more important element. Sooner or later a 

 continuous mat of vegetation is developed, in which the grasses 

 are usually the predominant plants, and the formerly bare soil 

 becomes covered over by a thin turf. Species of Cladonia and 

 Polytrichum also commonly play an important part in the 

 development of the turf. With the formation of a grassy sward, 

 the conditions come to approximate those of pastures. A few 

 shrubs and trees may have appeared, but on the whole the suc- 

 cession beyond this point is essentially the same as that in 

 abandoned fields, which is discussed in the following paragraphs. 



The association-types of abandoned fields. — The predominant 

 plants in open fields are the grasses. In dry pastures Danthonia 

 spicata and Poa pratensis are ordinarily the most abundant 

 species, but growing along with these and contributing to the 

 formation of the thin sward may be various perennial weeds, 

 particularly any of those mentioned in the second column of the 

 preceding list as characteristic of fallow fields, together with 

 other herbaceous perennials such as Fragaria virginiana, Tri- 

 foliuni repens, and Antennaria neodioica. Species of Cladonia 

 and Polytrichum also are usually present here; sometimes the 

 ground cover consists almost wholly of Polytrichum and 

 Leontodon. 



