T 11 K (J K A SS KS ( 1 1 • '1' K N X K.S8 K K. (15 



more or less spreading, the midiUe awn usually about an inch lon;^, 

 slij^htlv exceedinj^- the lateral ones. Callus slender-pointed, hairy. 

 On dry and usually poor s(jil, common. September — October. 



5. Aristida Striata Michx. 



Platr X I\. Fi^airo 7<5. 



This may occur within the State. It resembles //. purpurascens, 

 but the leaves are more ri^^nd and involute, and the upper eni])ty 

 o;-lume is distinctly lonij;-er than the lower. The awns are shorter 

 (one-half inch), subecjual, and all divergent or rellexed. 



6. Aristida oligantha Michx. 



IMatc \'X. Figure 77. 



A tufted annual with slender, l)ranchini^ culms, six to twelve 

 inches high, narrow leaves and loosely few- flowered racemes. 

 Sheaths smooth: ligule a fringe of short hairs; leaf-blade two to 

 six inches long, involute filiform, at least when dry. Panicle race- 

 mose, four- to six-flowered. Spikelets nine to eleven lines long (ex- 

 clusive of the awns); empty glumes three- to five nerved, subequal, 

 a little shorter than the flowering glume, more or less awn-pointed; 

 flowering glume scabrous, at least above, three-awned, awns 

 nearly equal or the lateral a little shorter, divergent, one to two 

 inches long. Callus soft-hairy, acute. 



Dry, gravelly or sterile soil, common. August to October. Of 

 no economic value. 



19. STIPA Linn. Sp. PI. yS (1753). 



Spikelets one-flowered, usually on long filiform pedicels in ex- 

 panded or rarely narrow panicles, rachilla articulated above the 

 empty glumes, and produced below the flowering glume into a 

 strong, bearded, obconical and sharp-pointed callus. Glumes 

 three, the first two empty, thin-membranaceous, subequal, acute or 

 bristle-pointed, the third or floral glume narrow, sub-coriaceous, 

 closely rolled around the flower and shorter palea, terminating by 

 a twisted and geniculate simple awn, which is articulated with its 

 apex. Grain terete and closely enveloped by the hardened fruit- 

 ing glume. Tufted perennial grasses, with very narrow or invo- 

 lute leaves and usually open panicles. 



Species about 100, widely distributed throughout the tropical 

 and temperate regions of the world. Twenty-four species are re- 

 corded as occurring within the United States, chiefly southwes- 

 tern. Only one comes within the State. 



I. Stipa avenacea Linn. Black Oat-grass, 



Plate XX. Figure 78. 



An erect perennial one to three feet high with, very narrow 

 leaves and a lax, few- flowered panicle. Lower leaves four to six 

 inches long, the membranaceous ligule one to two lines long. The 

 lower nearly erect rays of the nodding panicle, usually in pairs, 

 and one- to two-flowered. Empty glumes four to four and one-half 



