Pethybuidge & PuAEGEK — VefjetatloH South of Duhlin. 153 



Bosses of granite rising here and there bring in a few pronounced 

 xerophytes, such as : — 



The upper limit of the association, where it is usually succeeded by 

 that of U. Gallii, is often climatic, and consequent on exposure ; and 

 where the ground is steep, one association succeeds the other with a 

 tolerably sharp line of demarcation, and without change of soil or 

 water conditions. Elsewhere the upper limit of U. europmis is an 

 edaphic phenomenon, and caused by the appearance of peat, in which 

 case the supervening V. Gallii association is generally diluted with a 

 plentiful sprinkling of Calluna, in lieu of the characteristic Agrostis 

 sward. 



The most characteristic associations in this zone are the Ulex 

 Gallii association with its somewhat varying facias, the Pteris associa- 

 tion, and the not very extensive Nardus association. 



As one ascends from the farm-land on the U. europmis area, Vlex 

 Gallii makes its appearance among its stronger-growing congener, and 

 by degrees becomes completely dominant. The general appearance of 

 typical Gallii ground is quite different from that of typical U. europceus 

 ground. The rough, untidy surface of vegetation, interspersed with 

 small trees, bushes, and patches of grass, is replaced by a uniform 

 surface of low rounded bosses, very dense, and placed close together, 

 but with sheep-walks between ; and it is to the grazing of sheep 

 and rabbits that the roundness of the bosses is partly due. Other 

 bushes or trees are completely absent, though a stray Bramble or 

 stunted Blackthorn or Holly may occur. Agrostis vulgaris^ Erica 

 ciyierea, Calluna vulgaris, Galium saxatile hold their own in the 

 bosses of Gallii, straggling up through the dense, prickly surfaces. 

 In some areas, however, these bosses are far apart, or even almost 

 absent ; and here the upland grasses come in, forming a dense sward. 



In other cases U. Gallii is practically absent, and its place is taken 

 by a dense growth of Erica cinerea, the other plants of the association 

 remaining pretty much the same. The substratum here is usually 

 peaty, but dry. 



Ulex Gallii. 

 Sedum anglicum. 



Cotyledon Umbilicus, 

 Erica cinerea. 



The Zone of Hill-Pastuek. 



The Ulex Gallii Association. (G.) 



