FLOWERING PLANTS AND FERNS OF ARIZONA 125 



in New Mexico has been reported as having a narcotic effect on 

 horses and slightly on sheep, but not on cattle. The toxic principle 

 is unknown. An Old World species, esparto (S. tenacissima L.), is 

 used in the manufacture of fine paper and cordage. 



Key to the species 

 1. Terminal segment of the awn plumose, flexuous, up to 12 cm. long. 



1. S. NEOMEXICANA. 



1. Terminal segment of the awn not plumose (2). 



2. Lower segment of the once-geniculate awn conspicuously plumose, the 



hairs 5 to 8 mm. long 2. S. speciosa. 



2. Lower segment of the awn glabrous, scabrous, or pubescent, but not plumose 



(3). 

 3. Lemma densely villous with white hairs 3 to 4 mm. long; awn once-genic- 

 ulate 3. S. CORONATA. 



3. Lemma pubescent or sometimes villous toward the apex, the hairs not 



more than 2 mm. long (4). 



4. Panicles open, the slender branches ascending or spreading; lemma more 



than 7 mm. long (5). 



5. Ligule about 2 mm. long; mature lemma dark brown, 7 to 8 mm. 



long, papillose-pubescent; callus acute, 1 mm. long; awn about 



3 cm. long, the terminal segment straight 4. S. pringlei. 



5. Ligule 3 mm. long or longer; mature lemma pale (6). 



6. Mature lemma 8 to 12 mm. long, glabrous or sparsely pubescent 

 above the callus; callus acuminate, 3 mm. long; awn 10 to 15 

 cm. long, the terminal segment long and flexuous- 5. S. comata. 



6. Mature lemma 5 to 7 mm. long, pubescent 6. S. eminens. 



4. Panicles narrow, usually rather dense, the branches appressed, florifer- 



ous from the base (7). 



7. Lemma conspicuously villous toward the apex, the hairs 2 mm. long 



(8). 



8. Apex of the lemma with lobes 0.8 to 1.5 mm. long, the lemma 



evenly villous all over 7. S. lobata. 



8. Apex of the lemma not lobed or obscurely so, the lemma con- 



spicuously villous above, less so below 8. S. scribneri. 



7. Lemma pubescent, the hairs not more than 1 mm. long (9). 



9. Awn 4 to 6 cm. long, obscurely geniculate, the terminal segment 



flexuous 9. S. arid a. 



9. Awn 2 to 3 cm. long, twice-geniculate, the terminal segment 



straight (10). 



10. Sheaths villous at the mouth; panicle as much as 30 cm. long 



and 2 cm. thick, the lower nodes villous. _ 10. S. robusta. 



10. Sheaths glabrous at the mouth ; panicle 5 to 15 cm. long, rather 



narrow, the lower nodes glabrous (11). 



11. Hairs at apex of the lemma about as long as the others; awn 



mostly more than 2 cm. long 11 S. columbiaxa. 



11. Hairs at apex of the lemma longer than the others; awn 

 mostly 1.5 to 2 cm. long; leaf blades slender, involute, 

 crowded toward the base of the plant. 



12. S. lettermani. 



1. Stipa neomexicana (Thurb.) Scribn., U. S. Dept. Agr., Div. Agrost. 



Bui. 17: 132. 1899. 

 Stipa pennata var. neomexicana Thurb. in Coult., Man. 

 Rocky Mount, 408. 1885. 

 Apache, Navajo, Coconino, Mohave, Yavapai, and Pima Counties, 

 3,500 to 5,500 feet, dry, sandy or rocky hills and plains. May to Au- 

 gust. Western Texas and Colorado to Utah and Arizona. 



2. Stipa speciosa Trin. and Rupr., Acad. St. Petersb. Mem. VI. Sci. 



Nat, 5 1 : 45. 1842. 

 Apache, Navajo, Coconino, Mohave, Yavapai, Pinal, and Pima 

 Counties, 3,000 to 7,000 feet, dry rocky hills and canyons. April to 



