HOW TO KNOW THE GRASSES 



12a. Central awn spirally coiled at the base, 



13 



12b. Central awn not coiled 14 



1 3a. Glumes about equal in length; lateral awns about Va as long as 

 the central one. Fig. 197. 



Aristida dichotoma Michx. 



Annual; tufted, in small, shallowly-rooted 

 clumps; culms 20 — 40 cm. tall. The panicles 

 are very slender, almost racemose. The spe- 

 cies of Aristida are sometimes called wire- 

 grasses or needlegrasses. They are typically 

 grasses of depleted ranges or poor, sterile 

 soils. This species is found on dry sandy or 

 rocky open ground or in open sterile woods. 

 Forage value negligible. August — October. 



Figure 197 



13b. Glumes imequal, the first V2 to ^^ as long as the second. Fig. 198. 



Aristida basiramea Engelm. 



Annual; culms in small tufts, 30 — 50 

 cm. tall; leaf blades harsh, 1 — 2 mm, 

 wide; panicles slender, raceme-Uke, 5 

 — 10 cm. long, at the tips of the culms 

 and in axils of the upper leaf sheaths. 

 Dry sterile soil, open ground. August — 

 October. 



10 - 



Var. curtissii (Gray) Shinners has very 

 short lateral awns, 2 — 4 mm. long. Penn- 

 sylvania and Virginia to Wisconsin, 

 Wyoming, Colorado and Arkansas. 



Figure 198 



106 



