256 GRAMINE^. 



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 aiiex. 



33. Avena. Spikelet 2 -several-flowered. Lower i)alet rounded on the back, 2-toothed at tij). 



Awn from the midnerve only. 



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



2-puintcd at apex. Awn from near the cleft, from the nudnerve only. 



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



awned from near the base. 



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



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



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



Subtiibe VL FESTUCACEi'E. 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, 

 -i- 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. 

 +- -t- 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. 

 ++ 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. Kceleria. Glumes and lower palet membranous, keeled, acute or mucronate. Panicle con- 



tracted, spike-like. 

 ++ ++ Lower palet pointless and awnless (except in Mclicn), blunt, the nerves parallel. 

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



44. Eatonia. Glnmes 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 flatfish on the back, 7-nerved or more, membranous at tip. Fertile 



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

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

 Flowers diojcious. 



= = = Glumes 1 -3-nerved. 



47. Lophochleena. 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 

 nnich shorter than the florets. , . , 



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



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

 in <; up into joints. i r • i r i +i 



49. Atropis. Lower palet chartaceous, convex or rounded on the back, faintly o-neived, tfie 



nerves not reaching the obtuse subdenticulate or mucronulate apex. 



50. Poa, Lower palet laterally compressed, mostlv keeled, 5-nerved, membranous, the margnis 



or nerves below with cobwebby hairs or pubescent ; upi)er i)alet falling with the lower. 



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



Spikcli't flattened, usually manv-flowered. 



52. Steuochloa. Glumes long and narrow, much exceedhig the 2 or 3 deciduous florets. Lower 



palet 3-nerved. 



-i- +- Lowest floweis all jierfect : grain adherent to the palets. 



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



S[)ikelets somewhat heart-shaped. 



