256 GRAMINE^E. 



Lower palet usually bearing on the back or between its teeth a twisted bent or straight 

 awn. Ovary sometimes hairy at top. 



* Spikelets with two or more lower florets perfect. 



32. Danthonia. Spikelets several -flowered. Lower palet rounded on the back. Awn formed 



from the three united middle nerves, proceeding from the cleft at the apex. 



33. Avena. Spikelet 2 - several-flowered. Lower palet rounded on the back, 2-toothed at tip. 



Awn from the midnerve only. 



34. Trisetum. Spikelet 2 -several-flowered. Lower palet compressed and keeled, 2-toothed or 



2-pointed at apex. Awn from near the cleft, from the midnerve only. 



35. Aira. Spikelet 2-flowered, with or without a rudiment of a third flower. Lower floret 



awned from near the base. 



* * Spikelets 2-flowered, with one flower staminate. 



36. Arrhenatherum. Lower flower staminate, awned ; upper perfect and usually awnless. 



37. Holcus. Lower flower perfect, awnless ; upper staminate and awned. 



Subtribe VI. FESTUCACEJ:. Spikelets panicled, several - (rarely 2-) many-flowered, the 

 rhachis usually prolonged and bearing an imperfect floret or a bristle. Palets pointless, 

 or the lower tipped with a straight and (except in Bromus) terminal awn. 

 * Abortive flowers of several empty palets in a separate spikelet from the perfect ones. 



38. Lamarckia. Panicle unilateral, spike-like. 



* * Abortive or staminate flowers in the same spikelet with the perfect ones. 

 +- Lower 1 or 2 florets staminate or neutral. 



39. Phragmites. Spikelets in an ample panicle, with 1 staminate floret below 2 to 4 perfect 



ones ; rhachis bearded with long hairs. 



40. Eremochloe. Spikelets in a short nearly simple panicle, with 2 neutral florets below one 



fertile one, beyond which is a triple hairy rudiment. 



+- +- Lowest flowers all perfect : grain not adherent to the palets : joints of the rhachis bearded 



only in Tricuspis. 



41. Tricuspis. Lower palet bearded on the 3 nerves, one or all of which project into short 



awns. 



H- Lower palet pointed, awned or acute, the nerves, when present, running into the point. 



42. Dactylis. Glumes and lower palets herbaceous, awn-pointed, compressed-keeled. Spikelets 



in dense 1-sided clusters in a 1 -sided panicle. 



43. Koeleria. Glumes and lower palet membranous, keeled, acute or mucronate. Panicle con- 



tracted, spike-like. 



n- ++ Lower palet pointless and awuless (except in Melica), blunt, the nerves parallel. 

 = Lower glurne 1 -nerved, the upper 3-nerved. 



44. Eatonia. Glumes very unlike, the upper much broader than the linear lower one and 



wrapped around the flowers. 



-.= = One or both glumes 5-nerved or more. 



45. Melica. Lower palet flattish on the back, 7-nerved or more, membranous at tip. Fertile 



flowers 1 to 3, the upper enwrapping the 1 to 3 imperfect ones. 



46. Distichlis. Lower palet much compressed laterally, many-nerved, somewhat coriaceous. 



Flowers dioecious. 



= ==== Glumes 1- 3-nerved. 



47. Lophochleeiia. Lower palet prominently 7-nerved, its midnerve produced as an awn at the 



2-toothed or truncate scarious apex. Upper palet appendaged on the nerves. Glumes 

 much shorter than the florets. 



48. Glyceria. Lower palet rounded on the back, the 5 to 7 nerves not reaching the scarious 



mostly blunt apex. Spikelets many-flowered, deciduous at maturity, the rhachis break- 

 ing up into joints. 



49. Atropis. Lower palet chartaceous, convex or rounded on the back, faintly 5-nerved, the 



nerves not reaching the obtuse subdenticulate or mucronulate apex. 



50. Poa. Lower palet laterally compressed, mostly keeled, 5-nervcd, meinbranous, the margins 



or nerves below with cobwebby hairs or pubescent ; upper palet falling with the lower. 



51. Eragrostis. Lower palet 3-nerved, keeled, deciduous, leaving the persistent upper one. 



Spikelet flattened, usually many-flowered. 



52. Steiiochloa. Glumes long and narrow, much exceeding the 2 or 3 deciduous florets. Lower 



palet 3-nerved. 



-t- -i- Lowest flowers all perfect : grain adherent to the palets. 



53. Briza. Lower palet rounded, very obtuse, pointless, many-nerved, becoming ventricose. 



Spikelets somewhat heart-shaped. 



