538 GRAMINE^E. (<&RASS FAMILY.) 



87. BROMUS. Lower palea convex or keeled on the back, mostly awned or bristle-bearing bo- 



low the 2-cleft tip, 6 - 9-nerved. Styles subterminal. 

 * * Culms herbaceous, often tall and reed-like. Lowest flower sterile. Grain free. 



88. UNIOLA. Spikelets very flat ; the one or more lowest flowers neutral, of a single empty 



palea. Flowers strongly compressed keeled, crowded, coriaceous. 



89 PHRAGM1TES. Spikelets strongly silky-bearded on the rhachis, loosely-flowered, the low- 

 est flower staminate or neutral. Paleae membranaceous. 



* * * Culms woody, suffruticose or arborescent. 



40. ARUNDINARIA. Spikelets flattened, loosely 6-14-flowered : the jointed rhachis naked. 



Subtribe 5. HOKDEINE.E. Spikelets 1 - several-flowered, sessile on opposite sides of a zigzag 

 jointed rhachis (which is excavated or channelled on one side of each joint), forming a 

 spike Glumes sometimes abortive or wanting. Otherwise as hi the preceding subtribe 

 * Spikelets single at each joint of the rhachis, 1-flowered. Spikes often several. 



41. LEPTURUS. Spikelets almost immersed in the excavations of the slender rhachis 



* * Spikelets single at each joint of the rhachis, several-flowered. Spike solitary. 



42. LOLIUM. Glume 1, external : spikelets placed edgewise on the rhachis. 



43. TKITICUM. Glumes 2, transverse (right and left) ; spikelets placed flatwise on the rhachia 



* * * Spikelets 2 or more at each joint of the rhachis. Spike solitary, 

 i- Glumes anterior, forming a sort of involucre for the cluster of spikelets. 



44. HORDEDM. Spikelets 1-flowered, 3 at each joint, but the two lateral usually sterile. 



45. ELYMDS. Spikelets 1 - several-flowered, all perfect and similar. 



i- -i- Glumes none or 1 - 2 awn-like rudiments. 



48. GYMNOSTICHUM. Spikelets few-flowered, somewhat pedicelled, 1 - 3 at each joint 



Subtribe 6. AVENE^E. Spikelets 2 - several-flowered, panicled ; the rhachis or base of the 

 flowers often villous-bearded. Glumes mostly equalling or exceeding the flowers. Low- 

 er palea bearing a twisted, bent, or straight awn on its back or below its apex (hi No. 48 

 between the teeth) ; the upper 2-nerved. Stamens 3. 



* Flowers all perfect, or the uppermost merely rudimentary. 

 t~ Lower palea truncate or obtuse, its summit mostly denticulate or eroded 

 47. AIRA. Awn on the back or near the base of the palea, bent or straight. 



<- i- Lower palea cleft at the apex into 2 acute or sharp-pointed teeth, 

 w- Awn borne between the sharp or awn-pointed teeth ; proceeding from 3 middle nerres. 

 48 DANTHONIA. Lower palea rounded on the back ; the awn flat, spirally twisted. 

 <+ ** Awn below the apex or dorsal, proceeding from the midnerve only. 



49. TR1SETUM. Lower palea compressed-keeled. Awn mostly bent or flexuous. 



60. AVENA. Lower palea rounded on the back. Awn mostly twisted or bent. 



* * One of the flowers staminate only. 



61. AllRHENATHERUM. Lower flower staminate ; the perfect one commonly awnless ; the 



uppermost a rudiment : otherwise as No. 60. 



62 IIOLCUS. Lower flower perfect, awnless ; the upper staminate and awned : rudiment 

 none. 



TRIBE II.. PHALARIDE^E, Trin. (not of Kunth). Spikelets 3-flowered ; the upper 

 most or middle (terminal) flower perfect; the two lower (one on each side) imperfect, 

 either stamiuate, neutral, or reduced to an inconspicuous rudiment. 



Subtribe 1. ANTHOXANTH&ffi. Lateral flowers mostly awned, staminate or neutral, of 1 or 2 



paleae ; the perfect one awnless and diandrous. Upper palea 1-nerved. 

 53. HIEIIOCHLOA. Lateral flowers staminate and triandrous, of 2 paleae. 



64. ANTHOXANTHUM. Lateral flowers neutral, each of a single awned palea. 



Subtribe 2. PHALARIDE.E Proper. Lateral flowers reduced to a small neutral rudiment on 

 each side of the fertile oue ; which is awnless and triandrous. 



65. PHALAUIS Glumes boat-shaped, keeled, enclosing the coriaceous fertile flower, which ia 



somewhat flattened laterally. 



