GRASSES OF OHIO 307 



a hairy callus at the base, terminating in a simple, strong persistent, 

 bent, twisted awn ; palet 2-nerved, small ; grain narrow, free, tightly 

 enclosed in the fruiting lemma. 



1. Stipa spartea Trim Porcupine-grass. A tall, slender grass 

 with erect, simple stems, 2-4 ft. high, with involute leaf blades and 

 loose, narrow panicles, finally long-exserted. Empty glumes ac- 

 uminate into long, slender points, glabrous ; lemma brownish, ap- 

 pressed-pubescent below with a long, rigid, scabrous, twisted, usually 

 bent awn ; callus acuminate, very sharp-pointed, densely clothed with 

 silky, appressed hairs. The awns are highly hygrometric, and the 

 sharp-pointed fruit is injurious to animals, by penetrating the skin. 



On plains, prairies, and sandy places. June, July. Erie County, 

 where it occurs on Cedar Point. 



49. Aristida L. Triple-awn-grass. 



Tufted annuals or perennials with narrow leaves and usually 

 with loose, narrow panicles. Spikelets 1 -flowered ; empty glumes 

 unequal, narrow, acute or acuminate ; lemma somewhat indurated, 

 convolute, terminating in a three-branched awn ; palet thin, 2-nerved ; 

 grain elongated, free, tightly enclosed in the lemma. 



1. Awns separate to the base, not articulated to the lemma. 2 



1. Awns united below into a long twisted neck and articulated to the lemma. 



A. tuberculosa. 



2. Lateral awns much shorter than the middle one. 3 



2. Lateral awns not much shorter than the middle one. 4 



3. Middle awn coiled at the base. A. dichotoma. 



3. Middle awn not coiled at the base. A. gracilis. 



4. Outer empty glume 5-7-nerved ; annuals. A. oligantha. 

 4. Outer empty glume 1-3 nerved; perennials. A. purpurascens. 



1. Aristida dichotoma Mx. Poverty-grass. An annual tufted 

 grass with wiry much-branched stems, y 2 -2 ft. high, loose, glabrous 

 sheaths, much shorter than the internodes, and narrow, simple, few- 

 flowered, spike-like panicles, often reduced to racemes, the lateral 

 ones often sessile and partly enclosed in the sheaths. Lemma with 

 a horizontal awn, coiled at the base, with the two lateral awns erect 

 and very short. 



In dry sandy soil. Aug., Sept. Scioto, Vinton, Fairfield. 



2. Aristida oligantha Mx. Few-rlowered Triple-awn-grass. An 

 annual, tufted grass with wiry, branched, erect, solid stems, loose 

 sheaths, and few-rlowered, lax, spike-like racemes or panicles. Empty 

 glumes unequal, awned ; lemma scabrous above with three nearly 

 equal, divergent awns. 



In dry sterile soil. Aug., Sept. Cuyahoga County. 



