538 GRAMINEJE. (grass family.) 



37. BROMTJS. Lower palea convex or keeled on the back, mostly awned or bristle-bearing be- 



low the 2-cleft tip, 5 - 9-nerved. Styles sub terminal. 

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



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



palea. Flowers strongly compressed keeled, crowded, coriaceous. 



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



est flower staminate or neutral. Palea? membranaceous. 



* * * Culms woody, suffruticose or arborescent. 



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



Subtribe 5. IIordeime.3. 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 

 spikt . Glumes sometimes abortive or wanting. — Otherwise as in the preceding subtribn 

 * Spikelets single at each joint of the rhachis, 1-flowored. 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. TRIT1CUM. 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. 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- +- Glumes none or 1-2 awn-like rudiments. 



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



Subtribe 6. AvenejE. 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. 

 +- 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. 



+- -t- 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 awn flat, spirally twisted. 



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



49. 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. ARRIIENATHERUM. 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. PHALARIDEjE, 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. AntfioxanmEjE. Lateral flowers mostly awned, staminate or neutral, of 1 or 2 

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



53. HIEROCIILOA Lateral flowers staminate and triandrous, of 2 palese. 



54. ANTHOXANTIIUM. 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 one ; which is awnless and triandrous. 



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



somewhat flattened latex-ally. 



