GRASS FAMILY 



12. Aristida desmantha Trin. & Rupr. 

 Western Aristida. (Fig. 308.) 



Arislidti dfsmmitlia Trin. & Rupr. Mem. A cad. St. 

 IVtersb. i YI. i 5: 109. 1842. 



Culms i-2 tall, erect, branched, smooth and 

 glabrous. Sheaths shorter than the internodes, 

 smooth, glabrous or the lower sometimes pubes- 

 cent ; ligule short ; leaves 6'-i2' long, less than 

 \" wide, attenuate into a slender point, smooth 

 beneath, scabrous above ; panicle about 6' long, 

 the branches slender, ascending ; outer scales 

 of the spikelet about equal, the third one 

 shorter ; awns spreading or reflexed, somewhat 

 coiled, united at base into a column less than 

 i" long, which is articulated to the scale. 



In dry soil, Kansas (?), the Indian Territory and 

 5. Aug.-Sept. 



22. STIPA L,. Sp. PI. 78. 1753. 



Generally tall grasses, the leaves usually convolute, rarely flat, the inflorescence panicu- 

 late. Spikelets i-flowered, narrow. Scales 3; the two outer narrow, acute or rarely bearing 

 an awn, the third rigid, convolute, with a hairy callus at the base, and bearing a more or lev 

 bent awn, which is spiral at the base, and articulated to the scale. Palet 2-oerved. St.. 

 3, rarely fewer. Styles short, distinct Stigmas plumose. Grain narrow, free, tightly en- 

 closed in the scale. [Greek, in allusion to the tow-like plumes of some species.] 



A genus of about 100 species, distributed throughout the temperate and tropical zone*. Betide* 



the following, some 20 others occur in the southern and western parts of North America. 



Outer scales of the spikelet 2" -6" long: 



Obtuse or blunt-pointed, 2" in length. I. 5. J/avM>*. 



Acute, 4"-6" in length. 



Awn less than five times the length of the scale. 

 Awn more than seven times the length of the scale, 

 iter scales of the spikelet 10" long or more. 

 Base of panicle usually included in the upper sheath; third scale 4" -6" lonn ; awn aleaaer, 



curled. 

 Panicle exserted from the upper sheath; third scale 7" -12" long, bent. 5. S. sfcrttm. 



i. Stipa Macounii Scribn. Macoun's Stipa. (Fig. 309.) 



Riiliardstniii A 

 1856. Not Link, 1833. 



G3 M >' W 3. *4Q. 



Stif>a Macotinii Scribn.; Macoun Cat C.; 

 390. 1890. 



Culms glabrous, i-2 tall, erect, simple, slen- 

 der, smooth or somewhat scabrous. Sheath* 

 shorter than the internodes; ligule about t" 

 long, obtuse or truncate; leaves 3'-$' long, 

 W~\" wide, flat, becoming involtite-seUceou* 

 in drying, scabrous; panicle 

 tracted, the branches i'-a' Ion :>akcl 



below ; spikelets borne at the ends of the 

 branches; outer scales about 2" long, obtuse or 

 blunt-pointed, glabrous; third scale somewhat 

 shorter, pubescent with long appresaed 

 hairs, callus obtuse; awn 4" 5" loK. con'. 



New Hrunswicktotl 



to Maine. New Hampshire. I.-iU S 

 Montana. July. 



