538 GRAMINE^E. (GRASS FAMILY.) 



3T. BROMUS. Lower palea convex or keele<\ on the back, mostly awned or bristle-bearing be- 

 low the 2-cleft tip. 5 - 9-nerv;d. Styles subterminal. 

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



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



palea. Flowers strongly compressed keeled, crowded, coriaceous. 



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



est flower stamiuate or neutral. Palea; meiubranaceous. 



* * * Culms woody, suffruticose or arborescent. 



40. ARUNDINARIA. Spikelets flattened, loosely 5- 14-flowered : the jointed rhachis naked. 



Bubtribe 6. HORDKISE^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 

 epikt . Glumes sometimes abortive or wanting. Otherwise as in the preceding subtrilx* 

 * 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. TRITICUM. Glumes 2, transverse (right and left) ; spikelets placed flatwise on the rhachis, 



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

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



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



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



<~ +- Glumes none or 1- 2 awn-like rudiments. 



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



Subtribe 6. AVENE^B. 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 (in No. 18 

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



* Flowers-all perfect, or the uppermost merely rudimentary. 

 H- 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. 

 * Awn borne between the sharp or awn-pointed teeth ; proceeding from 3 middle nerve* 



48. DANTIIONIA. Lower palea rounded on the back ; the a\vu flat, spirally twisted. 



H- -H- Awn below the apex or dorsal, proceeding from the niidnerve only. 

 40. TRISETUM. Lower palea compressed-keeled. Awn mostly bent or flexuous. 



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



* * One of the flowers staminate only. 



51. ARRIIENATIIERUM. Lower flower staminate; the perfect one commonly awnless ; the 



uppermost a rudiment : otherwise as No. 50. 



52. HOLCUS. Lower flower perfect, awnless ; the upper staminate and awned : rudiment 



none. 



TRIBE II. PHAL.ARIDEJE, Trin. (not of Kunth). Spikelets 3-flowered ; the upper- 

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

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



Subtribe 1. ANTHOXANTIEJE. Lateral flowers mostly awned, staminate or neutral, of 1 or 2 



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

 5-. HIEROCIILOA Lsiteral flowers staminate and triandrous, of 2 palese. 



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



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

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



55. PHALARIS. Glumes boat-shaped, keeled, enclosing the coriaceous fertile flov-er, which Is 



somewhat flattened laterally. 



