6 



SEEDS OF QUACK-GBASS AND OF CERTAIN WHEAT-GRASSES. 



QUACK-GRASS (aGROPYRON REPENS, l). 



The spikelets of quack-grass (fig. 4) vary from one-lialf to three- 

 fourths of an inch in length and contain four to seven seeds. Both 

 glumes and individual seeds may be merely acute or may bear a 

 short awn at the apex. The glumes may diverge somewhat, well 

 exposing the seeds, or they may be nearly parallel, nearly covering 

 the lower seeds. The two faces of the spikelet may be about 

 equally convex and the angles between the glumes about equal 

 on the two faces, or the faces may be unequally convex and the 

 glumes more widely separated on the more convex face than on 



Fig. 3.— a mixture of seeds of awnless brome-grass (a), partial spikelets of Ijrome-grass (6), spikelets and 



glumes of quack-grass (c), and seeds of quack-grass (d). (Enlarged about 2i times.) 



the other. The seeds extend beyond the tips of the glumes from 

 slightly to half the length of the glumes. The glumes (see figs. 4 

 and 5) are five veined or seven veined, the veins distinct, the cen- 

 tral or keel vein a little coarser than the others, giving the glumes 

 a slightly keeled form. The margins of the glumes are thin, papery, 

 narrowing to the apex, and usually merge abruptly into the pointed 

 or awned tip. 



^lature spikelets of quack-grass tend to retain the individual 

 seeds and in consequence whole or partial spikelets alwaj^s appear 



[Cir. 73] 



