HOW TO KNOW THE GRASSES 



7b. Leaves flat, usually green; upper surface of blades finely nerved, 

 with 25 — 40 nerves across the width. Fig. 164. 



QUACKGRASS Agropyron repens (L.) Beauv. 



Perennial; with extensive creeping rhizomes; 

 culms 50 — 100 cm. tall; leaves flat, green, 

 often hairy on the upper surface; spike slen- 

 der, with erect spikelets. Some of the plants 

 have awned lemmas. Quackgrass is one of 

 the worst grass weeds in the northern states. 

 It produces good forage but is not intention- 

 ally planted as a crop. Waste ground, road- 

 sides, fields and meadows. May — July. In- 

 troduced from Europe. 



10 





Figure 164 



8a. Spikelets erect, pressed against the rachis; rachis joints at least 

 5 nun. long 9 



8b. Spikelets spreading away from the rachis, overlapping; rachis 

 joints about 1 mm. long . Fig. 185. 



CRESTED WHEATGRASS Agropyron deserforum (Fisch.) Schult. 



Perennial; tufted; culms 60—100 cm. tall. The 

 strongly divergent spikelets distinguish this spe- 

 cies from all others of this genus. Crested 

 wheatgrass is a recent introduction from the 

 Old World and has proved very useful for re- 

 grassing abandoned crop lands and depleted 

 ranges in the northern great plains states. A 

 valuable forage species. June — August. Former- 

 ly known as Agropyron cristatum. 



Fiaure 165 



88 



