The Natural History of British Grasses. 



529 



•greatly indebted for some valuable information, and from which 

 we extract the following table, showing the percentage of water 

 in three species of Poa compared with PIdeum pratense. 



G rass. 



Date of 

 Collection. 



Water 

 per Cent. 



Xature of soil. 



Poa annua .. 

 ,, prafensis 

 „ irivialis ,, 



I'Idcum pratensis 



May 23 

 June 11 

 June 18 

 July 11 



79*14 i Loam, ■«-ith gravelly subsoil. 



67 • 14 I Dry calcareous loam. 



73-60 I Calcareous loam. 



57-21 ■ Ditto. 



From this, no less than long observations of its history and gene- 

 ral characteristics, we should feel disposed to rank Poa trivialis 

 as a very inferior grass to Poa -pratensis, holding indeed, as far as 

 the value of its hay and herbage is concerned, an intermediate 

 position between the latter and Poa annua. As a weed, the Poa 

 trivialis is often exceedingly annoying, especially on poor damp 

 clays. We have seen it in some of the stretches of the Fuller's- 

 earth, choking even the scanty crop of grain which this stratum 

 will grow when ill tlrained or otlierwisc unmitigated ; it is how- 

 ever easily got rid of by thorough-draining, and letting light and 

 air into this stubborn soil. 



3. Poa pratensis — smooth-stalked meadow grass — is very con- 

 stant in pastures, and especially in those of the best quality ; it 

 yields a good bulk for the rick, and sends up a quantity of herb- 

 age for the aftermath, which is less injured by cold and other 

 climatal changes than almost any other species ; its range is very 

 wide, being found on dry uplands, in deep loams, and in both 

 flooded and irrigated meadows, and should always be largely 

 intermixed with seeds in the laying down of permanent pasture. 

 Thus it will be seen that our experience of this species is quite 

 ^t variance with that of the ' Hortus Gramineus Woburnensis,' 

 in Avhich it is stated, that " upon the whole it is an inferior grass ; 

 its strong creeping roots exhaust the soil ; its growth after mowing 

 is slow ; and its spring growth, though early, is inconsiderable ; 

 nnd upon the whole it is unfit to be introduced among the supe- 

 rior sorts." 



Now, as regards the creeping roots, these are never strong in 

 the pasture ; if, however, the grass be employed in turf- walks 

 in the garden, it then spreads strong rhizomes into the plots in 

 contact, on which account it slioidd never be brought to such 

 situations ; l)Ut how rhizomes could exhaust the soil except by 

 producing grass, we cannot make out; the truth is, that all good 

 grasses exhaust the soil if taken off in the shape of hay, and this 

 one especially by reason of its good crops ; but such should be 



