230 COMPOSITION (JF SOME INDIGENOUS (JHASSES. 



of little use to the fanner, as it is rarely eaten by stock, being 

 rather harsh to the touch, due probably to the excessive propor- 

 tion of silica present, as shown by the high percentage of ash, 

 much of which is insoluble in acids. 



Cjjpcnis cscidcntus is typically hygrophilous and of a simple 

 unbranched habit of growth. Hence its position on the list as the 

 lowest in fibre is readily correlated wath the fact that little 

 sclerenchyma and conducting tissue are required. 



ROTTBOELLIA COMPRESSA. 



In EotthoeUia co»ipressa we have an ecological point of some 

 interest. At Cedara in January, 1920, an experimental plot of 

 Eottboellia was planted on a typical hillside soil, well drained, 

 and quite different in type from the vlei soil of the farm where 

 this species finds its home, and whence young plants were 

 obtained for establishing this plot. The results were remarkably 

 good, although no figures were obtained as to the weight of hay 

 produced per acre. The grass flourished under its new conditions, 

 without being specially watered or treated in any way once it had 

 become established. It matured more rapidly and reached the 

 flowering stage some two or three weeks earlier than in the neigh- 

 bouring vlei. Its life, however, was shorter, as it became fibrous 

 and its leaves withered sooner than in the vlei. Had it been 

 mown or grazed off no doubt the period of growth would have 

 been prolonged. Hence it was possible to collect onlj^ two 

 samples before it became so coarse and rust-affected that an 

 analysis would be misleading. 



The samples from this trial plot were fairly uniform in com- 

 position, showing rather more protein in the later sample. The 

 corresponding samples in the vlei series are those taken two 

 weeks later than in the experimental plot, and these two also show 

 similar variation. The first vlei sample, taken on 24/12/21, was 

 somewhat immature, and hence is not used in comparing the two 

 series. 



The plot samples show slightly less fibre but much more 

 protein — nearly twice as much as in the vlei samples. Ash and 

 crude fat are very slightly higher, calorific value is decidedly 

 higher, and nutritive ratio much narrower. Thus a grass that 

 is relished by stock and has good feeding value has its main 

 defect, its lack of protein, remedied by change of habitat. 

 Further, by making its environment more okin to that of the 

 ordinary veld its composition seems to tend towards that of the 

 climax grasses. 



Phosphate Context of the Ash. 



At the suggestion of Dr. Green, of Onderstepoort, the scope 

 of the present work was inci-eased so as to include the phosphate 

 content of the ash. On account of the known general deficiency 

 in phosphates of the soils of South Africa, and hence the deficiency 

 of this constituent in the ash of veld grasses — to which is attrib- 



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