70 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Tribe IX. FESTUCEAE. 



Plants tall and stout, 2-4 meters high; inflorescence a large plumelike panicle. 



40. PHRAGMITES. 

 Plants low or moderately tall, rarely over 1.5 meters high ; inflorescence not plumelike. 

 Lemmas prominently 3-nerved. 

 Lemmas villous on the nerves below; panicle large, drooping, viscid. 



41. TKIDENS. 

 Lemmas glabrous; panicles not viscid, sometimes odoriferous. 



42. ERAGROSTIS. 

 Lemmas 5-many-nerved. 

 Upper florets reduced, the empty lemmas inclosed one within the other, forming 

 a club-shaped mass. Glumes broad and papery; spikelets in a small panicle, 



pendulous on capillary pedicels 43. MELICA. 



LTpper florets not differing from the lower in shape. 

 Spikelets with 1-4 sterile lemmas below the fertile ones, these persistent with 



the glumes 44. UNIOLA. 



Spikelets with no sterile lemmas below the fertile ones. 

 Spikelets strongly flattened, subsessile in 1-sided clusters at the ends of long 

 naked panicle branches, these spreading in anthesis, erect in fruit. 



45. DACTYLIS. 

 Spikelets neither strongly flattened nor in clusters. 

 Lemmas awnless, obtuse or subacute. 

 Lemmas keeled, the spikelet compressed; nerves rather faint. . .46. POA. 

 Lemmas convex, the spikelet turgid or subterete; nerves usually 



prominent 47. PANICTJLARIA. 



Lemmas awned or sharp-pointed. 

 Lemmas rounded on the back, the awn, if present, from the tip. 



48. FESTUCA. 



Lemmas keeled toward the summit, awned from between 2 minute teeth 



(awn very short in B. unioloides) 49. BROMUS. 



Tribe X, HORDEAE. 



Spikelets more than one at each node of the rachis, awned. 

 Spikelets not all alike, the cluster consisting of a sessile perfect spikelet with a 



pediceled spikelet reduced to the 2-4 awns on each side 54. HORDETTM. 



Spikelets all alike. 

 Glumes well developed; spikelets oppressed or ascending, imbricate. 



55. ELYMTJS. 

 Glumes obsolete or reduced to small bristles; spikelets remote, horizontally 



spreading 56. HYSTRIX. 



Spikelets solitary at each node of the rachis. 

 First glume (except in the terminal spikelet) wanting; spikelets placed edgewise 



to the rachis 50. LOLITJM. 



First glume present; spikelets placed flatwise to the rachis. 

 Racbilla disarticulating between the florets; plants perennial. 



51. AGROPYRON. 

 Rachilla disarticulating above the glumes only; plants annual. 

 Glumes subulate, 1-nerved; lemma3 ciliate on the keel and exposed margin. 



52. SEC ALE. 

 Glumes lanceolate, 3-nerved; lemmas not ciliate 53. TRITICTJM. 



Tribe XI. BAMBOSEAE. 

 A single genus 57. ARUNDINARIA. 



