FLOWERING PLANTS AND FERNS OF ARIZONA 121 



1. Plants perennial (5). 

 5. Spikelets 4 to (i mm. long (6). 



6. Panicle contracted, more or less included in the sheaths; second glume 



shorter than the glabrous lemma 5. S. aspek. 



G. Panicle open, exserted; second glume about as long as the lemma. 



6. S. INTERRUPTUS. 



5. Spikelets 1 to 3 mm. long (7). 



7. Spikelets about 1 mm. long; lower panicle branches in distinct whorls. 



7. S. PYRAMIDATUS. 



7. Spikelets 1.5 to 3 mm. long; lower panicle branches not whorled (8). 

 8. Sheaths glabrous or nearly so at the mouth (9). 



9. Panicle loose, 1 to 2 times as long as broad, the branches naked below, 

 the branchlets spreading; leaf blades mostly involute. 



12. S. AIROIDES. 



9. Panicle relatively dense, 30 to 60 cm. long, the numerous, relatively 



short, crowded, densely flowered branches floriferous nearly to 

 base, the branchlets appressed; leaf blades usually flat. 



13. S. WRIGHTII. 

 8. Sheaths with a conspicuous tuft of hairs at summit (10). 



10. Panicles open, the branches spreading, naked at base (11). 



11. Panicle branches loosely flowered, the branchlets and pedicels 

 implicate, spreading 8. S. flexuosus. 



11. Panicle branches densely flowered, the branchlets and short 



pedicels appressed 9. S. cryptandrus. 



10. Panicles contracted, spikelike (12). 



12. Spikelets 2 to 2.5 mm. long; culms slender, usually less than 1 



meter high 10. S. contractus. 



12. Spikelets 2.5 to 3 mm. long; culms robust, 1 to 2 meters high. 



11. S. GIGANTEUS. 



1. Sporobolus vaginiflorus (Torr.) Wood, Class-book, ed. 3, 775. 



1861. 



Vilja vaginiflora Torr. in A. Gray, Gram, and Cyp. 1: no. 3. 

 1834. 



Fort Huachuca and Willcox (Cochise County), sandy soil or open 

 waste ground. Maine and Ontario to Minnesota and Nebraska, 

 south to Georgia, Texas, and Arizona. 



2. Sporobolus neglectus Nash, Torrey Bot. Club BuL 22: 464. 1895. 

 Black Springs, Coconino National Forest, Coconino County, in deep 



black gravelly loam (Talbot C-13). Quebec and Maine to North 

 Dakota south to Maryland, Tennessee, and Texas; Washington and 

 Arizona. 



3. Sporobolus ramulosus (H. B. K.) Kunth, Rev. Gram. 1: 68. 1829. 



Vilja ramulosa H. B. K., Nov. Gen. et Sp. 1: 137. 1815. 



Coconino, Cochise, and Pima Counties, 5,400 to 8,000 feet, dry or 

 moist open ground, August to September. Colorado, New Mexico, 

 and Arizona, to Guatemala. 



4. Sporobolus microspermus (Lag.) Hitchc, Wash. Acad. Sci. Jour. 



23: 453. 1933. 



Milium microspermum Lag., Gen. et Sp. Nov. 2. 1816. 

 Sporobolus confusus Vasey, Torrey Bot. Club Bui. 15: 293. 

 1888. 



Navajo County to Mohave County, south to Cochise, Santa Cruz. 

 and Pima Counties, 3,500 to 8,000 feet, dry or usually moist open 

 ground and borders of marshes, August to October. Nebraska to 

 Montana and eastern Washington, south to Costa Rica. 



