52 CLASSIFICATION ACCORDING TO [CH. 



A. alba, L. Only the variety A. stolonifera is of moderate 

 value for pasture, especially on poor soils, as it lasts late 

 into autumn : the others are weeds, like couch-grass. 



Agrostis is full of difficulties for the beginner. The weed-forms 

 often spring up after wheat has been cut, and count as " twitch," 

 like Agropyrum. 



All the ordinary forms — A. stolonifera, A. vulgaris, and 

 A. canina — may be included in A. alba (Linn.). On dry hills a 

 close tufted grass, with setaceous leaves, and in rich soils creeping 

 and luxuriant with broad leaves. It is one of the few grasses that 

 thrive in wet soils. 



The chief points in the flat-leafed forms are the thin, dry leaves, 

 rough on both sides and on the margins, with distinct raised ridges, 

 and the base of the leaf narrowing suddenly into its insertion with 

 the sheath, with no auricle, but with a long membranous ligule. 

 The sheath not coloured, and the blade convolute. 



Again, A. stolonifera has a long, serrated, acute ligule, while 

 A. vvlgaris has a much shorter, entire and truncate one, and 

 narrower leaves. 



Agropyrum is the grass most likely to lead to confusion. Its ears, 

 lower ridges, very short or obsolete ligule, and pubescence (sometimes 

 glabrous) distinguish it. 



Cynoaurus sometimes gives trouble (see p. 50) with Alopecurtts 

 pratensis : the sheaths, ligule and flattened ridges should suffice for 

 distinction. 



Alopecurus geniculatus is even more like Agrostis, but its ridges 

 are more prominent and sharp, and its aquatic habit and bent 

 "knees'' distinguish it. 



Alopecurus agrestis, in dry corn-fields, has a thickened ligule, 

 sometimes coloured, and is annual or biennial, but otherwise very 

 Uke Agrostis. 



Alopecurus pratensis, L. (Meadow Foxtail). Large 



grass with stolons ; very early, and much prized as pasture 



and hay, but soon dies out on light poor soils. Especially 



good for stiff soils. Sheaths long, ridged, brown or nearly 



black at the base as they age. Ligule distinct and obtuse, 



