160 Agricultural Section [PT n 



cultivated there under the name of Kentucky Blue-grass. It is 

 also found in Australia and other parts of the southern hemi- 

 sphere. It is abundant in Britain in meadows, pastures, on road- 

 sides, etc. Its numerous and widely-creeping rhizomes enable it 

 to withstand extremes of heat and cold better than most other 

 useful grasses, and this fact no doubt partly accounts for its wide 

 distribution. 



Poa pratensis thrives better upon soils which possess a loose 

 texture than upon those which are heavy and compact. Its de- 

 velopment from seed is slow, and in the first year only small tufts 

 of herbage are formed. During the second season the under- 

 ground rhizomes spread considerably and its maximum growth 

 is attained by the third year. When this stage is reached it is 

 capable of covering the ground fairly evenly with a fine growth 

 of "bottom" grass. 



This plant can be most usefully used as a constituent of per- 

 manent pasture on soils which are loose or light, and of only 

 medium quality. Its growth commences early in the spring 

 especially upon warm dry soils. As a meadow plant it is less 

 valuable and its aftermath is small. On more fertile and moister 

 soils Poa trivialis is much to be preferred for either pasture or 

 meadow. Its nutritive value appears to be below that of most 

 pasture grasses. For alternate husbandry it is unsuitable owing 

 to its slow development and creeping habit. 



Poa pratensis can be usefully employed as a constituent of 

 the turf for lawns, especially for those on dry soils, or which are 

 required to "wear" well under hard usage. 



Commercial Seed. 



The seed is obtained mostly from North America, and owing 

 to its relative cheapness it is seldom adulterated. In some years 

 when it is scarce the seeds of the closely allied Poa compressa, L. 

 (Flat-stemmed Poa or Canadian Blue-grass) are either mixed with 

 it or wholly substituted. Compare Figs. 138 and 142. 



The proportion of chaff sometimes reaches 20 per cent, or more, 

 but in well-cleaned samples it should not exceed five to seven per 

 cent. The usual weed impurities are various Sedges (Carex sps.), 

 Mouse-eared Chickweed (Cerastium vulgatum, L.), Shepherd's 

 Purse (Capsella Bursa-pastoris, L.) and Sheep's Sorrel. 



