20 



THE SEEDS OF THE BLUEGRASSES. 



Poa nemoralis L. 



WOOD MEADOW GRASS. 



Spikelets 2 or 3 flowered; florets 22-3 mm. long, lanceolate or ovate-lanceolate, 

 mostly acute at the apex, light brown, sometimes yellowish tinged near the apex; 

 glume rather broadly keeled and somewhat arched at the back; margins of the 

 glume narrowly infolded quite to the apex or hyaline-edged and often flaring above 

 the middle; intermediate veins very indistinct;" keel and marginal veins silky 

 pubescent below the middle; basal web slight; surface between the veins glabrous; 

 palea nearly equal to the glume, evidently shorter in florets having a flaring apex, 

 its keels hispid-ciliate and usually covered by the margins of the glume; rachilla 

 segment varying from one-fourth to three-fourths of the length of the glume, the 

 sterile rachilla segment very uniformly much longer than the others, more or less 

 appressed pubescent, the pubescence somewhat variable and sometimes nearly want- 

 ing; aborted floret of the sterile rachilla segment often one-half as long as the seg- 

 ment; grain Ij mm. long, rather slender, semitranslucent. (Fig. 7.) 



7 3 



% i 



Fig. 7.— .Seeds of wood meadow grass {Poa nemoralis): a-c, back views; d and e, side 

 views; /-/, front views; j, a terminal floret. 



Commercial wood meadow grass seed is not rubbed in preparation 

 for market, and therefore possesses much of its rather persistent and 

 prominent silky pubescence, and the thin tips of the florets are mostly 

 uninjured. The pubescence of the rachilla segment is persistent and 

 present in most of the seeds of all pure samples of this species. It 

 afl'ords the most marked characteristic by which the seeds of P. nemo- 

 ralls may be distinguished from those of other commercial species of 

 Poa. The conspicuously longer rachilla segments of the terminal 

 florets are noticeably abundant in samples of this species, since these 

 florets constitute from one-third to one-half of all the seed. The 

 abundance of the long rachilla segments is helpful in distinguishing 

 these seeds from those of other Poas. 



Commercial seed of P. nemoralis is apt to be very much adulterated 

 with other species of Poa. Of a number of samples examined less 

 than half were true to name. One was nearly pure Canada bluegrass 

 seed, and the rest consisted in part of one or all of the following 

 species: P. j^ratensis, P. compressa, and P. trivially. 



The following comparison of characters should render it compara- 

 tively easj'^ to distinguish the seeds of P. nemoralh from those of the 

 other .species. 



