T 1 1 1 : ( J H ASS i:s < > f T k n n kss k k. 11 



38. Spikes stout, witli two to several herma])hrodite flowers 



in each spikelct |o 



39. Flowerinj^ ^lume and rudiment awned . . . 36. Chloris. 



39. Flowerin);^ ^lume and rudiment awnless . . 34. Cynodon. 



40, Axis of the spike projecting beyond the si)ikclcts. second 



empty j^lume awn-poinied . . . 40. DactylocteDium. 



40. Axis of the spike with a terminal spikelet, none of the 



glumes awn-pointed 39. Eleusine. 



41. Spikelets strictly one-flowered, no prolongation of the ra- 



chilla or rudiment of a second flower, crowded -md 

 strongly flattened 35. Spartina. 



41. Spikelets two- to three-flowered, or at least with the rachilla 



prolonged beyond the first flower 42 



42. Spikes short, flowering glume trifid, the divisions subulate 



or awn-pointed 38. Bouteloua. 



42. Spikes (or racemes) very slender, filiform, (two to six 



inches long); flowering glume not trifid 43 



43. Spikelets with only one hermaphrodite flower, its glume 



bearing a slender awn just below the bifid apex .... 

 37. Gymnopogon 



43. Spikelets with two to four hermaphrodite flowers, jinnies 



awnless 41. Leptochloa. 



44. Rachilla or flowering glume, at least of the fertile flower, 



with long hairs which equal or exceed the glumes in 

 length 45 



44. Rachilla or flowering glumes naked or with hairs much 



shorter than the glumes 47 



45. Spikelets unisexual (plants di(jecious) the staminate spike- 



lets naked; culms solid 41 Gynerium. 



45. Spikelets hermaphrodite; culms hollow 46 



46. Hairs on the glumes only 43 Arundo. 



46, Hairs an the rachilla only 44. Phragmites 



47. Flowering glumes three-nerved, the middle as well as the 



marginal lateral nerves silky-villous below, and ex- 

 tended bevond the glumes into three mucronate points . 

 . . . . ' 45. Triodia. 



47. Flowering glumes three- to many-nerved, lateral nerves not 



marginal nor extended beyond the glume 4S 



48. Flowering glumes three-nerved, usually falling with the 



grain in advance of the paleas which remain attached to 

 the continuous rachilla 46. Eragrostis. 



48. Flowering glumes and paleas falling together, each glume 



carrying a joint of the articulate rachilla 49 



49. Empty illumes three to six at the base of each spikelet . . 



50. Uniola 



49. Empty glumes two at the base of the spikelet 50 



50. Spikelets heart-shaped at the base, glumes ventricose . . 



51. Briza. 



50. Spikelets not heart shaped, glumes not ventricose .51 



