32 INDICATOR-PLANTS [CH. 



without reference to the quality of the soil, that they are 

 not indicative. The latter are often termed ruderal or 

 vagabonds (see p. 29). Without attempting too rigid a 

 classification of Grasses in this connection — which would 

 be premature in this early state of our knowledge — the 

 following remarks are at least generally true. 



A few grasses are Indicators of chalk and limestone — 

 e.g. Briza media, Kosleria cristata, and the exotic species 

 Stipa pennata and Melica ciliata. 



The following are said to indicate a sufficiency of 

 potassium salts, 



In moister soils. 



Digraphis amndinacea. Arundo Phragmites. 



Phleum prateiue. MoUnia ccerulea. 



Avena pubescens. Olyceria fluitans. 



In drier soils. 



Anthoxanthum odoratwm. Dactylis glomerata. 



Alopecniriis pratensis. Gynosurus cristatus. 



Agrostis alba. Poa pratensis. 



Holeus lanatus. P. trimalis. 



Arrhenatherum. P. com/pressa. 



Koeleria cristata. Festuca elatior. 



Briza media. Lolium perenne. 



Grasses like Bromus arvensis indicate the existence of 

 clay in the soil. 



While the following are indicative of sand, 



Aira caryophyllea. Festuca ovina. 



A. prcecox. Bromus sterilis. 



A. canesce'iis. 



