112 Bulletin V. 2. 



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 dioecious); the staminate spikelets 



naked; culms solid . . .. .. ... 41. Gynerium. 



45. Spikelets hermaphrodite; culms hollow 46 



46. Hairs on the glumes only .42. Arundo. 



46. Hairs on the rachilla only 45. Phragmites. 



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



marginal lateral nerves silky-villous below, and extended 

 beyond the glumes into three mucronate points. 44. Triodia. 



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



marginal nor extended beyond the glume 48 



48. Flowering glumes three-nerved, falling w'th the grain in 



advance of the paleas which remain actached to the 

 continuous rachilla. (See Fig. 54.) 45. Eragrostis. 



48. Flowering glumes and paleas falling together, each glume 



carrying a joint of the articulate rachilla 49 



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



.49. Uniola. 



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



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



(See. Fig. 57.) 50. Briza. 



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



51. Flowering glumes three-nerved, rounded on the back, 



coriaceous, subulate-pointed 48. Diarrhena. 



51. Flowering glumes three to many nerved, herbaceous, 



membranaceous, or chartaceous 52 



52. Terminal sterile florets in each spikelet club-shaped, flowering 



glumes papery-membranaceous with a broad and scarious 

 apex ... 47. Melica. 



52. Terminal sterile florets not club-shaped 53 



53. Empty glumes nearly equal in length, but very dissimilar; 



the first narrowly linear, one nerved; the second broadly 



obovate, folded around the florets, three-nerved 



46. Eatonia. 



53. Empty glumes similar, but often of unequal length. - • 54 



54. Spikelets crowded in one-sided clusters on spreading 



branches, flowering glumes awn-pointed and strongly 

 ciliate on the keel above 51. Dactylis. 



54. Spikelets not crowded in one-sided clusters 55 



55. Spikelets of two forms, fertile and sterile, the latter pectinate 



and standing with the fertile; inflorescence terminal, 



spike-like 52. Oynosurus- 



55. Spikelets all alike 5^ 



