POACEAE 123 



Plants with no long rootstocks : stems tufted or single. 

 Leaf-sheaths glabrous. 



Upper leaf-sheaths enclosing panicles which are usually concealed, or some- 

 times partially protruding : terminal panicle contracted, narrow. 

 Annual. 1- S. vaginacflorus. 



Perennial. 



Flowering scale appressed-pubescent below with long hairs. 



Palet long-acuminate, sometimes almost awned, much exceeding 



the scale. 2. S. asper. 



Palet merely acute, about equalling the scale, rarely a little exceed- 

 ing it. ' 3. -S. canorircns. 

 Flowering scale glabrous. 



Stems slender : panicle very slender, usually less than 5 mm. broad : 

 spikelets 4 mm. long or less. 

 Spikelets 3 mm. long. 4. S. attenuatus. 



Spikelets 4 mm. long. 5. S. Drummondii. 



Stems stout : panicle broader, usually 1 cm. wide : spikelets 5-6 mm. 



long. 6. .S'. lonpifolhis. 



Upper leaf-sheaths not enclosing panicles. 



Panicle usually loose and open, its branches spreading or ascending, or if 

 erect the jaanicle not elongated. 

 Spikelets 2 mm. long or less. 



Panicle branches verticillate, at least the lower ones. 



Larger leaf-blades rarely exceeding 5 cm. in length. 7. S. argutus. 



Larger leaf-blades 1 dm. long or more. 8. .S. Domlngensis. 



Panicle branches scattered. 13. S. Buckley i. 



Spikelets 3 mm. long or more. 



Panicle branches verticillate. 9. S. ejuncidus. 



Panicle branches scattered. 



Empty scales very unequal, the first subulate, the second very 



broad. 10. 'S. heterolepis. 



Empty scales approximating each other in shape, the first lanceo- 

 late. 

 Basal leaf-blades 1.5 mm. wide or less. 11. S. Curtissii. 



Basal leaf-blades 3 mm. wide or mofe. 12. S. Flondanui'. 



Panicle narrow and elongated, spike-like. 15. X Indicus. 



Leaf-sheaths with a tuft of long spreading hairs on each side of the apex. 14. S. ct-gptandrus. 



Plants with long rootstocks. 



Panicle loose and open : rootstocks slender. 16. S. fwperifoliiis. 



Panicle contracted, spike-like : rootstocks stout : sand-binders. 17. S. Virginicus. 



1. Sporobolus vaginaeflorus (Torr. ) Wood. Stems 2-6 dm. tall, erect, slender: 

 leaf-blades 2 mm. wide or less, attenuate and slender above, tlie lower ones elongated, the 

 upper 2-8 cm. long : terminal panicle 2-5 cm. long : spikelets 3.5-4.5 mm. long, the scales 

 acuminate, the flowering one appressed-pubescent with long hairs. [S. vaginaeflorus var. 

 minor Scribn.] 



In dry soil, Massachusetts and New York to Nebraska, Georgia and Florida. Summer and fall. 



2. Sporobolus asper ( Michx. ) Kunth. Stems 6-12 dm. tall, erect : leaf-blades 7-35 

 cni. long, 2-4 nun. wide, attenuate into a long slender involute tip : panicle 5-13 cm. 

 long : spikelets 6-8 mm. long, the empty scales unequal, acute, the flowering scale ap- 

 pressed-pubescent below, much longer than the second one and much exceeded by the 

 long-acuminate palet. 



In dry soil, New York to Illinois, Florida and Texas. Summer and fall. 



3. Sporobolus canovirens Nash. Stems 3-10 dm. tall, erect : leaf-blades 2.5 dm. 

 long or less, 1-3 mm. wide, attenuate and filiform above : panicle 5-13 cm. long : spikelets 

 5-6 mm. long, the scales acuminate, the empty ones unecjnal, the flowering scale appressed- 

 pubescent below with long hairs, about equalling or a little exceeded by the acute palet. 



In dry sandy soil, Tennessee to Missouri, Kansas, Mississippi and Texas. Summer and fall. 



4. Sporobolus attenuatus Nash. Stems tufted, slender, 5-7 dm. tall, erect : leaf- 

 blades 4 dm. long or less, 1-2 mm. wide at the base, the upi)er portion filiform : panicle 

 5-7 cm. long, very slender : spikelets 3 mm. long, the scales acuminate, the empty ones 

 unequal, the second a little shorter than the glabrous flowering one which about equals 

 the acute palet. 



In dry soil, Mississippi. Fall. 



5. Sporobolus Drummondii (Trin. ) Vasey. Stems 5-10 dm. tall, erect, slender: 

 leaf-blades 3 dm. long or less, 1-3 mm. wdde, attenuate and filiform at the apex : panicle 

 1-1.5 dm. long, slender: spikelets about 4 mm. long, the empty scales acute, the first a 

 little shorter than the second, the flowering scale glabrous, acute or obtusish, longer than 

 the second one and abont equalling the acutish palet. 



In dry soil, Louisiana and Texas. Summer. 



6. Sporobolus longifolius (Torr.) Wood. Stems 4-12 dm. tall, stout, erect: leaf- 

 blades 5 dm. long or less, 2-5 mm. wide : panicle 2-3 dm. long, usually more or less in- 

 cluded in the upper leaf-sheath, sometimes entirely so : spikelets 5-6 mm. long, the scales 

 obtuse, the first about s as long as the second, the flowering scale glabrous, considerably 

 exceeding the second one, about equalling the palet or a little shorter or longer than it. 



In dry soil, Massachusetts to Iowa, Kansas and Arkansas. Fall. 



