MANUAL OF THE GRASSES OF THE UNITED STATES 



421 



Prairies, Quebec to Saskatchewan, 

 south to Connecticut, eastern Texas, 

 and Colorado. 



13. Sporobolus silveanus Swallen. 

 (Fig. 602.) Culms 85 to 115 cm. tall, 

 densely tufted, erect, scabrous ; sheaths 

 glabrous or scaberulous, pubescent 

 on the collar, the uppermost elongate, 

 the lower shiny, becoming more or 

 less papery with age; blades as much 

 as 45 cm. long, 1 to 2 mm. wide, 

 usually involute, curved or flexuous; 

 panicles 30 to 50 cm. long, the as- 

 cending branches rather distant, few- 

 flowered, naked at the base; spikelets 



5 to 6 mm. long, purple; first glume 

 3 to 4.5 mm. long, the second 4.5 to 



6 mm. long; lemma subacute; palea 

 as long as the lemma, the keels ob- 

 scure. % — Open woods, western 

 Louisiana and eastern Texas. 



14. Sporobolus curtissii (Vasey) 

 Small ex Scribn. (Fig. 603.) Peren- 

 nial, in dense tufts; culms slender, 

 30 to 70 cm. tall; basal sheaths pilose 

 at the throat; blades flat or folded, 

 flexuous, about 1 mm. wide, pilose 

 o"n the upper surface near the base; 

 panicle pyramidal, open, 7 to 20 cm. 

 long, the branches solitary or in twos, 

 ascending; spikelets appressed along 

 the main branches, bronze or pur- 

 plish, about 4.5 mm. long; glumes 

 about equal, acuminate, as long as 

 or longer than the lemma and palea. 

 % — Dry pine barrens, North Caro- 

 lina to Florida. 



15. Sporobolus teretifolius Harper. 

 (Fig. 604.) Perennial, in tufts; culms 

 erect, wiry, 60 to 80 cm. tall, sheaths 

 pilose at the throat; blades elongate, 

 slender, terete, wiry, flexuous, pilose 

 on the upper surface at base; panicle 

 pyramidal, open, 15 to 20 cm. long, 

 the capillary branches, branchlets, 

 and pedicels ascending to spreading; 

 spikelets purplish brown, 4 to 5 mm. 

 long; glumes acute, the first half as 

 long, the second as long as the equal 

 lemma and palea. % — Moist pine 

 barrens, North Carolina and Georgia. 



16. Sporobolus floridanus Chapm. 

 (Fig. 605.) Plants more robust than 

 S. curtissii, as much as 1 m. tall; 



Figure 600. — Sporobolus interruptus. Plant, X 1; 

 glumes and floret, X 10. (Rusby, Ariz.) 



sheaths keeled, the basal ones some- 

 what pilose at throat, the base in- 

 durate and shining, blades folded at 

 base, usually flat above, 2 to 5 mm. 

 wide, abruptly narrowed at apex; 

 panicle narrow, open, 15 to 35 cm. 

 long, the branches and branchlets 

 ascending; spikelets 4 to 5 mm. long; 



