Guilt : Botanical Survey of a Pasture. 



1 1 1 



What are the differences existing on this side of the ditch 

 which have brought about the enormously different herbage? 

 Here Cyiwsurus is entirely excluded, and there is a wealth of 

 different grasses which similarly do not appear, even in small 

 quantity {Alopecurus excepted), in the Cyiiosurus area. Now, if 

 the soil conditions here are totally different from those found in 

 the part just considered, it is only reasonable to suppose that 

 it is to the soil alone to which these differences can be attributed; 

 such as has been explained is the case. The surface soil, which 

 is that of a sandstone vrasli, is of good depth and open. It 

 receives much of the drainage water from the higher land in 

 the adjoining field, but as the basement clay follows almost 

 uniformly the surface gradient (which is about : in 25), there is 

 a considerable natural drainage until the neighbourhood of the 

 ditch is approached where the surface becomes horizontal. 



Now, Tussock forms a great proportion of the herbage on 

 this side as a pure grass ; it grows luxuriantly even where the 

 slope is greatest^ and on the ridges alluded to, where the 

 conditions are merging toward the dry. It is not so abundant 

 here, however, as where the slope runs itself out. Water, at 

 first sight, is the go\'erning factor, as the areas increase in size 

 as the slope is descended, but if this is the case, this grass 

 should also extend to the other side of the ditch where like 

 conditions prevail ; the ditch has not constituted an impassable 

 barrier, for its shallowness and artificial origin have precluded 

 this. 



Water, then, as the governing factor, is excluded, and also 

 every other factor, which exerts its characteristic effect on 

 vegetation, is eliminated, but soil. It is clear that we have 

 here and in the foregoing very marked examples of the direct 

 influence which the soil has on the nature of the herbage which 

 it supports, for differences in herbage have in all cases been 

 found to agree with differences in soil. 



With regard to the pure areas of Holcits, the same is 

 apparently the case, as it invariably occurs, either surrounding 

 the Tussock masses, or, with Tussock, dispersed through it. 

 This would naturally be expected, as these two grasses when 

 growing under suitable conditions are rather similar in habit, as 

 evidenced by their disputing the same places. Tussock, how- 

 ever, occurs in tufted and solid masses, therefore Holcus, the 

 lesser, must surround it. 



With Foxtail, however, although in the main the foregoing- 

 ;applies, the case is somewhat different. At first sight, and what 



1904 April I. 



