AGROSTIS. 151 



distinctive features are owing to the nature of the 

 ground. 



Var. aristata. Larger in its growth ; its leaves 

 rough, their sheaths smooth ; ligule more prominent 

 than in the normal form ; flowering glume awned from 

 a little above the base, and extending beyond the spike- 

 let, hence the distinctive name. The length of this awn 

 upon which the claim of the plant to rank as a variety 

 is founded, is extremely unreliable. Dr. Parnell, to 

 whom we are indebted for the notes on most of the 

 varieties, has taken immense pains to ascertain the limits 

 of their variability, and he says that this awn is some- 

 times so short as to be hardly perceptible. The other 

 distinctions which he records are : — the palea thin, half 

 as long as the flowering glume, furnished with a tuft of 

 short hairs. 



Var. vulgaris. This is often considered the typical 

 form, and either distinct altogether from A. alba, or the 

 more normal species, in which case A. alba is treated as 

 a variety of it. The careful Dr. Parnell treats them as 

 quite distinct. The smoothness of the sheaths, the 

 short, blunt ligule, and the lower outer glume being 

 toothed only on the upper part of the keel, are the prin- 

 cipal differences which he cites in the features of A. 

 vulgaris. This form of A. alba grows in dry situations, 

 over the same tracts of country as the normal form. 

 Cattle are said to dislike it. 



The A. alba is found in one or other of its forms 

 throughout Europe, and in Central Asia, North Africa, 

 and America. It flowers in July and August, and 

 ripens its seeds soon after the withering of the latest 

 flowers. Doubts are entertained by botanists as to the 

 permanency of any of the varieties, as they seem to de- 



