Tmk (ikAssKs OF Tknnksskk. Ill 



32. Spikclets two to inany-ilowered, all the flowers hermaphrodite 



or the uppermost imperfect or rudimentary 34 



33. Lower flower staminate, its ^lume lonj4--awned (jn the back 



from near the base 31. Arrhenatherum. 



;^^. Lower flower hermaphrodite, its glume awnless. 27 Holcus. 



34. Powering glumes thin and hyaline, carinate, awned from 



near the apex 29. Trisetum. 



34, Flowering glumes herbaceo-chartaceous, rounded on the 



back, two-toothed or bifid at apex, awned between the 

 teeth 35 



35. Awn terete, proceeding from the mid-nerve only. 30. Avena. 



35. Awn flat below, formed by the union of the three middle 



nerves of the glumes 32. Danthonia. 



36. Spikelets sessile or nearly so, in two rows along one side of 



the continuous axis forming unilateral racemes or spikes, 

 these racemed or digitate. (Tribe Chloride.k) 37 



36. Spikelets in opposite rows along a jointed rachis, forming a 



two-sided or equilateral, terminal spike. (Tribe Horde.k.) 59 



37. Spikes terminal or nearly so, digitate or whorled. (Fig. 56.) 38 



37. Spikes (or one-sided racemes) scattered along a common 



axis (usually racemed) 41 



38. Spikes slender, one hermaphrodite flower and a sterile 



rudiment of a second flower in each spikelet 39 



38. Spikes stout, with two to several hermaphrodite flowers in 



each spikelet 40 



39. Flowering glume and rudiment awned 35. Chloris. 



39. Flowering glume and rudiment awnless 33. Cynodon. 



40. Axis of the spike projecting beyond the spikelets. second 



empty glume awn-pointed . . 39. Dactyloctenium. 



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



glumes awn-pointed 38. Eleusine. 



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



rachilla or rudiment of a second flower, crowded and 

 strongly flattened 34. Spartina. 



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



prolonged beyond the first flower 42 



42. Spikes short (one inch or less), flowering glume trifid. the 



divisions subulate or awn-pointed. (Fig. 53.) 37. 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 



36. Gymnopogon. 



43. Spikelets with two to four hermaphrodite flowers, glumes 

 awnless 40. Leptochloa. 



