THE SELECTION OF GEASSES AND CLOVEES. 63 



turf is wanted for holding the soil together, there is no more 

 valuable plant. 



In the United States, where Poapratensis is known under the 

 name of Kentucky Blue Grass, or June Grass, it has been cultivated 

 with striking success, and when it has taken possession of a pasture 

 the value of the land is immediately enhanced. Americans grow 

 it on their richest soil, and are surprised that we use it so little 

 and never sow it alone. But in some parts of New Zealand this 

 grass has developed a very objectionable habit of groAvth which 

 overruns pastures, and is difficult to eradicate from arable land 

 when once it has obtained a footing. This fact does not 

 prove the worthlessness of the grass for British use. It is analo- 

 gous to the case of our familiar Sweetbriar, which since its intro- 

 duction into Tasmania forms dense thickets in that country, 

 entanghng and overpowering all other vegetation, throwing under- 

 ground suckers across fields, and matting the soil with its dense 

 mass of fibre. But we are not on that account inclined to sacrifice 

 the charming bush of our gardens and hedgerows. Neither the 

 merits of Poa pratensis when cultivated in America, nor its 

 demerits when sown in certain districts of New Zealand, how- 

 ever interesting they may be, need influence our employment of 

 a grass which experience has proved to be of great service in this 

 country. 



Dressings of nitrate of soda discourage the growth of this 

 grass, while mineral superphosphates combined with ammonia 

 salts foster it. 



The botanical description and chemical analysis are given 

 on page 158, facing an illusti^ation. 



Poa trivialis {Rough-stalked Meadow Grass, or Orcheston 

 Grass) diSers from Poa pratensis in having narrower foliage, a 

 long pointed instead of a blunt ligule to its leaf, fibrous instead 

 of creeping roots, and shghtly rough sheaths. The roughness 

 is only apparent to a sensitive touch, but is readily perceived 

 when the grass is drawn across the tongue. 



