GENUS 32. 



GRASS FAMILY. 



177 



3. Stipa avenacea L. Black Oat-grass. Fig. 420. 



Stipa avenacea L. Sp. PI. 78. 1/53. 



Stipa barbata Michx. Fl. Bor. Am. i: 53. 1803. 



Stipa virginica Pers. Syn. i : 99. 1805. 



Stipa bicolor Pursh, Fl. Am. Sept. 73. 1814. 



Culms glabrous, \-2\ tall, erect or leaning, simple, 

 smooth. Sheaths shorter than the internodes ; ligule 

 about i" long, obtuse; blades involute-filiform, smooth 

 beneath, scabrous above, the basal one-third to one- 

 half the length of the culm, those of the culm 3'-5' 

 long; panicle 5 '-8' long, loose, the branches lax, erect 

 or finally spreading, naked below ; outer scales of the 

 spikelet 4" -5" long, acute, glabrous; third scale a little 

 shorter, scabrous near the summit, black, pilose at base 

 and with a ring of short hairs at the top, otherwise 

 smooth and glabrous; callus hard, acute; awn \\'-2.\' 

 long, bent, loosely spiral below. 



In dry woods, Massachusetts to Wisconsin, Florida and 

 Texas. Feather-grass. May-June. 



4. Stipa comata Trin. & Rupr. Bunch-grass. 

 Needle-grass. Silk-grass. Fig. 421. 



Stipa comata Trin. & Rupr. Mem. Acad. St. Petersb. 

 (VI.) 5: 75- 1842- 



Glabrous, culms i-2 tall, erect, simple, smooth. 

 Sheaths usually longer than the internodes, smooth 

 or scabrous, the uppermost very long and inflated, 

 enclosing the base of the panicle; ligule i"-2" long, 

 obtuse; blades smooth or somewhat scabrous, the 

 basal involute-filiform, one-quarter to one-half as 

 long as the culm, the culm blades 3' -6' long, a little 

 broader than the basal ones, involute; panicle 6'-g' 

 long, loose, the branches 3 '-5' in length, erect- 

 ascending, naked at base; outer scales of the spikelet 

 g"-i2" long, glabrous, acuminate into an awn 2" -4," 

 in length; third scale 4"-6" long, callus acute; awn 

 4'-8' in length, slender, curled, spiral and pubescent 

 below. 



Dry places, Yukon to Iowa, Texas and California. 

 Porcupine- or Blow-out-grass. Needle and Thread. 

 June-July. 



5. Stipa spartea Trin. Porcupine-grass. Fig. 

 422. 



S. spartea Trin. Mem. Acad. St. Petersb. (VI.) i : 82. 1831. 



Culms glabrous, 2-4 tall, erect, simple, smooth. 

 Sheaths longer than the internodes, smooth or some- 

 what scabrous; ligule i"-2" long, obtuse; blades smooth 

 beneath, scabrous above, the basal one-third to one- 

 half as long as the culm, i" wide or less, usually invo- 

 lute, those of the culm 6'-i2' long, about 2" wide, 

 generally flat, attenuate into a long slender point ; 

 panicle finally long-exserted, 4'-io' in length, its 

 branches 3' -6' long, erect, naked below ; outer scales 

 of spikelet 12"-! 8" long, acuminate into a long slender 

 point, glabrous; third scale 7"-! 2" long, callus acute; 

 awn 4'-8' long, stout, usually twice bent, tightly spiral 

 and pubescent below, doubly spiral about the middle. 



On prairies, British Columbia to Michigan and Kansas. 

 June-July. 



