144 Proceedings of the Royal Irish Academy. 



The agrarian zone is occupied chiefly by the farm- land. XJndei- 

 this term may he included all the cultivated area and grazing lands, 

 and also the areas occupied by demesnes and pleasure-grounds. The 

 areas occupied by houses and streets, though yielding, if any, a modi- 

 fied and much-reduced flora, need not be distinguished from the farm 

 land, as both come under the same category, namely, area where the 

 influence of man is dominant, and where the natural plant-associations 

 have been broken up or destroyed. The limits of the farm-land are 

 fixed sometimes by questions of altitude and exposure, but more often 

 by the thinning-out of the glacial deposits. Where this latter occurs 

 on the lower ground in the agrarian zone, pastures, meadows, and till- 

 age usually give way to rough, broken ground, strewn with boulders of 

 granite, which rock also lies immediately beneath what shallow soil 

 there may be in such places. This rough ground is occupied by the 

 Gorse ( Vlex europceus) and the Pteris associations. Where the farm- 

 land reaches its upward limits, the zone of hill-pasture begins, although 

 between the two there is often a thin line of the Ulex europmis 

 association. In this zone several associations occupy the ground. 

 Thus in some places, though not very frequently, above the farm -land, 

 we find considerable areas of pretty pure grass-land in which the upland 

 grasses are well represented. This seems to be especially the case, as 

 on parts of Montpelier Hill, for instance, where there is still a fair 

 sprinkling of glacial gravel over the underlying rock. The greater part 

 of the area, however, is covered with that form of the gorse association 

 in which Ulex Galliiis the characteristic plant, and which will be fully 

 described in its proper place. Again, we find some areas in this zone 

 covered by an association in which the Purple Heather {PJ. cinerea) is 

 predominant; and this is frequently the case when the subjacent rocks 

 are the slates, &c., of the Silurian period, rather than the granite and 

 its debris. Finally, in this zone the Pteris andJimcus associations are 

 often well developed. 



In the moorland zone we have also several associations which form 

 the covering of vegetation. It is here that the influence of peat first 

 makes itself seriously felt. On the better-di\iined slopes CaUuna 

 reigns supreme. The flatter and wetter bogs present us with associ- 

 ations in which Scirpus C(Bspitosus and Eriopliorum angustifolium are 

 respectively predominant. The moss Racomitrium Imiiiginosum, grow- 

 ing in grey bosses, gives us another characteristic type of moorland ; 

 and on the drier hill-tops gives rise to the sort of moss-tundra mentioned 

 previously. 



