Genus 33. 



GRASS FAMILY. 



1 S3 



14. Aristida divaricata H. & B. Spreading Triple-awned Grass. Fig. 436. 



Aristida divaricata H. & B. ; Willd. Enum. Hort. Berol. 

 99. 1809. 



Culms il°-3° tall, tufted, erect. Sheaths over- 

 lapping, rough, usually with a tuft of long hairs on 

 each side at the apex; ligule a short ciliate ring; 

 blades smooth beneath, rough above, those of the 

 culm 6'-i2' long, i"-2" wide, erect or ascending; the 

 sterile shoots from one-third to one-half as long as 

 the culm, the leaves narrower; panicle comprising 

 one-half of the plant, or more, often included at the 

 base, its branches rigid, at length widely spreading; 

 spikelets, exclusive of the awns, about V long, 

 numerous; empty scales acuminate, usually awn- 

 pointed; flowering scale commonly slightly shorter 

 than the empty ones, firm, sometimes spotted with 

 purple, hispidulous above; awns not articulated to 

 the scale, the lateral ones shorter than the central, 

 which is 6"-io" long; callus pilose. 



Dry sandy soil, Kansas to Arizona and Mexico. 



15. Aristida tuberculosa Nutt. Sea-beach 

 Triple-awned Grass. Fig. 437. 



Aristida tuberculosa Nutt. Gen. 1 : 57. 1818. 



Glabrous, culms 6'-2° tall, erect, dichotomously 

 branched, smooth. Sheaths shorter than the inter- 

 nodes; ligule short, ciliate; blades s'-g' long, about 1" 

 wide, attenuate into a long slender point, smooth 

 beneath, scabrous above; panicle s'-8' long, branches 

 slender, ascending; outer scales of the spikelet about 

 equal, awned, the third scale shorter; awns divergent 

 or reflexed, more or less coiled, united at the base into 

 a column $"-6" long which is articulated to the scale. 



Sandy soil, especially on sea-beaches, Massachusetts to 

 Georgia. Also about the Great Lakes. Long-awned 

 Poverty-grass. Aug.-Sept. 



16. Aristida desmantha Trin.&Rupr. West- 

 ern Triple-awned Grass. Fig. 438. 



Aristida desmantha Trin. & Rupr. Mem. Acad. St. 

 Petersb. (VI.) 5: 109. 1842. 



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

 brous. Sheaths shorter than the internodes, smooth, 

 glabrous or the lower sometimes pubescent ; ligule 

 short ; blades 6'-i2' long, less than 1" wide, attenuate 

 into a slender point, smooth beneath, scabrous above ; 

 panicle about 6' long, the branches slender, ascend- 

 ing; outer scales of the spikelet about equal, the 

 third one shorter; awns spreading or reflexed, some- 

 what coiled, united at base into a column less than 

 1" long, which is articulated to the scale. 



In dry soil, Nebraska to Texas. Aug.-Sept. 



