65 



©iHgiual Mxiitlt^. 



ON AGROSTIS NIGRA, With. 

 By James E. Bagnall. 



(Tab. 227.) 



For some years past I have noticed an Ar/wstis growing on the 

 borders of corn and other cultivated fields (more especially in 

 marly and calcareous soils), which appeared to me to differ widely 

 from both A. vulgaris and A. alba ; so much so as to be at once 

 recognisable by any one accustomed to field observations, without 

 the trouble of gathering for closer insi^ection. 



More critical examination gives strongly-marked structural 

 differences, which I will endeavour to point out. From A. vulgaris 

 it differs in having larger flowers, with the glumes relatively longer 

 than the palea ; in having the lower glume more strongly serrulate 

 half its whole length, those of A. vulgaris being only faintly serru- 

 late one-third the whole length ; in the panicle branches being 

 more strongly toothed, more rigid, and more erect — those of A. 

 vulgaris bemg somewhat flexuous and divaricate ; in the leaf- 

 sheath being slightly rough, this roughness, however, varying much 

 according to the nature of the soil in which the plant grows — in 

 A. vulgaris the sheaths are quite smooth ; in the ligule being pro- 

 minent, oblong blunt and often jagged — in vulgaris the ligule is 

 very short and truncate ; and in its usually taller growth and more 

 robust habit. 



From A. alba it differs in the glumes not being serrulate from 

 the base upwards, in the panicle branches being bare of flowers for 

 a considerable distance from the main stem, and in the panicle 

 being open both in flower and fruit. 



When growing in light sandy soils A. nigra sends out numerous 

 underground shoots (soboles), often of considerable length and 

 much branched; these give origin to the new plants. In light 

 soils the plant often occurs in large roundish patches ; in marly or 

 clayey soils the soboles are shorter, and the plant has then a 

 thinner and more scattered growth. 



Specimens have been submitted to Professor Babington, who, 

 with his usual com-tesy and kindness, exammed them, and, in an 

 admirable letter on the plant, says — " Your Agrostis seems to differ 

 from our plants in several particulars, and is probably the A. nigra 

 of Withering. His quotation of Leers is a mistake, judging fr-om 

 both the figures and description in ' Fl. Herborn.' The pecuhar 

 points of your plant seem to be (1) the always spreading panicle ; 

 (2) the nearly undivided branches in the lower part ; (3) the long 

 truncate ligule. The roughness of the sheaths seems very slight, 



N. s. VOL. 11. [March, 1882.] k 



