606 GRAMINE^E. (GRASS FAMILY.) 



- t- Glumes none or 1-2 awn-like rudiments in their place. 



47. Gymiiostichum. Spikelets few-flowered, somewhat pedicelled, 1 - 3 at each joint. 



Sul> tribe 7. Avenerc. Spikelets 2 - several-flowered, panicled ; the rhachis or base of 

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

 Lower palet bearing a twisted, bent, or straight awn on its back or below its apex ; the 

 upper palet 2-nerved. Stamens 3. 



* Flowers all perfect, or the uppermost rudimentary. 



48. Danthonia. Spikelets several-flowered. Lower palet firm and rigid, rounded on the 



back, several -nerved, the 3 middle nerves running into the flattish twisted awn which 

 proceeds from the cleft at the apex. 



49. A vena. Spikelets 2 - several-flowered. Lower palet roundish on the back, and of firmer 



texture than the glumes, several-nerved, sharply 2-toothed or 2-cleft at the tip, the bent 

 or twisted awn rising only from the midnerve at or below the cleft. 



60. Trisetum. Spikelets 2 - several-flowered. Lower palet laterally compressed and keeled, 

 sharply 2-toothed or 2-pointed at the apex, the slender awn rising at or near the cleft, 

 from the midnerve only. 



51. Aira. Spikelets small, 2-flowered, with or without the rudiment of a third flower. Palets 



thin or scarious, the lower awned from towards the base. 



* * One of the flowers staminate only. 



52. Arrlieiiatlierum. Lower flower staminate ; the perfect one commonly awnless ; the 



uppermost a rudiment : otherwise as in Avena. 



53. Helens. Lower flower perfect, awnless ; the upper staminate and awned: rudiment 



none : otherwise resembling Aira. 



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. Antlioxaiitlieeo. Lateral flowers mostly awned, staminate or neutral, 



of 1 or 2 palets ; the upper one awnless and diandrous. Upper palet 1-nerved. 

 51. Ilierocliloa. Lateral flowers staminate and triandrous, of 2 palets. 



55. Aiithoxanthum. Lateral flowers neutral, each of a single awned and hairy palet. 



Subtribe 3. Phalarideee proper. Lateral flowers reduced to a small neutral rudiment 

 or abortive pedicel on each side of the fertile one ; which is awnless and triandrous. 



56. Phalaris. Glumes boat-shaped, keeled, enclosing the coriaceous fertile flower. 



Tribe III. PANICEJE. Spikelets 2-flowered ; the lower flower always imperfect, either 

 staminate or neutral ; in the latter case usually reduced to a single empty palet (placed 

 next the lower glume, if that be present) ; the upper (terminal) flower (placed next the 

 upper or inner glume) only fertile. Embryo and groove (when present) on the outer side 

 of the grain ! (next the lower palet of the fertile flower). (Flowers polygamous, or herni- 

 gamous (when the lower flower is neutral), or sometimes seemingly simple and perfect, 

 from the suppression both of the lower glume and of the upper palet of the neutral flower, 

 sometimes monoecious, or rarely dioecious. Rarely both glumes are wanting.) 



Subtribe 1. Paspaleee, Griseb. Glumes and sterile palets herbaceous or membrana- 

 ceous : palets of the fertile flower of firmer texture, coriaceous or chartaceous, awnless, not 

 keeled, more or less flattened parallel with the glumes. 



* Spikelets appearing as if simply 1-flowered, from the suppression of the lower glume, the 

 single neutral palet of the sterile flower apparently occupying its place. (Awnless.) 



57. Mili urn. Spikelets not jointed with their pedicels, all alike in a terminal open panicle. 



58. Amphicarpum. Spikelets jointed with their pedicels, of 2 sorts ; one in a terminal 



panicle ; the other subterranean, on radical peduncles. 



59. Paspalnm. Spikelets jointed with their short pedicels, all alike, plano-convex, in one- 



sided spikes or spiked racemes. 



