>.<s&t! 



SEEDS OF QUACK-GRASS AND OF CERTAIN WHEAT-GRASSES. 5 



larcjer than the other, the palea. The seeds are broadly crrooved on 

 the side bearin^r the palea (&) and rounded on that bearino^ the lemma 

 (c). A portion of the cluster axis, termed the "rachilla seojment" (/), 

 appears at the base of the grooved palea of the seed. The individual 

 seeds of Agropyron are so similar that no attempt is made here to 

 distinguish the kinds by them. The number of seeds per spikelet 

 varies from four or five to twelve. Both glumes and seeds may be 

 either acute or awn pointed at the tips. 



The spikelets are attached facewise to the axis bearing them (see 

 fig. 2, a and h), differing from other 

 grasses in which the spikelets are at- 

 tached edgewise to the axis. 



The spikelets and seeds of Agropyron 

 are generally straw colored or tinged 

 with green. 



THE SEEDS OF AGROPYRON AND OF 



BROME-GRASS COMPARED. 4 



Seeds of awnless brome-grass (see fig. ■ ■ 

 3, a) are about three-eighths of an inch 

 long, flattened and thin, light brown, 

 the darker grain evident through the ; 



thin palea, which is more or less l|i&|p^ ^^i^,. 



A\Tinkled and bears two slender, hairy a b 



veins. The slender rachilla segment is fiq. 2.-a section of the seed cluster of 



, . rni 11111 c quack-grass, showing the mode of attach- 



han-y. Ihe rounded back, or lemma, ot ^ent of the spikelets to the rachis, or 



the seed is more or less distinctly five cluster axis: a, side view; 6, edge view. 



veined. The seeds of brome-grass are 



larger than those of quack-grass (fig. .3, d) and smaller than all 

 except the smallest of the spikelets of the latter (fig. 3, c). Samples 

 of brome-grass seed usually contain partial spikelets of brome-grass 

 (fig. 3, h), which are not likely to be confounded with the spikelets of 

 c^uack-grass when compared with the latter. The generally lighter 

 color of the quack-grass seeds and spikelets, together with the oppo- 

 site attachment of their glumes, serves to distinguish them from 

 the brome-grass seeds. 



THE SEEDS OF QUACK-GRASS, SLENDER WHEAT-GRASS, AND 

 WESTERN WHEAT-GRASS DESCRIBED. 



The following descriptions are designed to point out the con- 

 trasting characters of the mature spikelets of quack-grass, slender 

 wheat-grass, and western wheat-grass, as they appear in commercial 

 samples of seed. 



[Cir. 73] 



