GRAMINEAE. 65 



One-several empty scales above the flower. 



Lower empty scales 4 ; spike solitary, dense. 55. Campulosus. 



Lower empty scales 2. 



Spikes in false whorls or closely approximate ; scales long-awned. 



56. Chloris. 

 Spikes remote, or the lowest only approximate. 



Spikelets scattered or remote on filiform spikes. 



57. Gymnofogon. 

 Spikelets crowded, sometimes 2-flowered. 



Spikes 4 or less ; spikelets numerous, 25 or more. 



59. Bouteloiia. 

 Spikes numerous, 12 or more ; spikelets few, 12 or less. 



60. Atheropogon. 

 2-3 perfect flowers in each spikelet. 



Spikelets densely crowded : spikes usually digitate. 



Spikes with terminal spikelets. 62. Elensine. 



Spikes without terminal spikelets, the rachis extending beyond them into a 

 point. 63. Dactyloctenium. 



Spikelets distinctly alternating : spikes remote. 64. Leptochloa. 



Spikelets dioecious, very unlike ; spikes short ; low prairie grass. 65. Bulbilis. 



Tribe X. FESTUCEAE. 



Rachilla with long hairs enveloping the flowering scale ; tall aquatic grass. 



67. Phragmites. 

 Rachilla and flowering scales naked or hairy, hairs much shorter than the scales. 



Stigmas barbellate ; spikelets in clusters of 3-6 in the axils of stiff spinescent leaves. 



66. Munroa. 

 Stigmas plumose ; spikelets not in the axils of leaves ; inflorescence various. 



Spikelets of two forms, the fertile i-3-flowered, surrounded by the sterile, con- 

 sisting of many empty pectinate scales. 86. Cynosurus. 

 Spikelets all alike. 



Flowering scale i-3-nerved, or rarely with faint additional intermediate 



nerves. 

 Flowering scales membranous ; seed not beaked nor exserted from the 



scales. 

 Lateral nerves of flowering scale pilose. 



Internodes of the rachilla long, the deeply 2-lobed flowering 

 scale attached by a long-pointed callus, which is copiously 

 pilose on the outer surface. 70. Triplasis. 



Internodes of the rachilla and the callus of the flowering scale 



short, blunt. 



Panicle simple or compound, contracted or open, the 

 spikelets on pedicels of varying length. 



69. Tricuspis. 



Panicle composed of long branches along which the ap- 

 pressed spikelets are arranged on short pedicels. 



72. Diplachne. 

 Lateral nerves of the flowering scale glabrous. 



Callus of the flowering scale conspicuously pubescent with long 



hairs. 

 Panicle contracted ; flowering scale broadly oval, rounded 



at the apex. 74. Rhombolytrum. 



Panicle open and diffuse ; flowering scales lanceolate and 



acute. 71. Redfieldia. 



Callus of the flowering scale glabrous. 



Second empty scale similar to the first. 



Panicle narrow, the branches appressed. 



Panicle dull, interrupted ; rachilla articulated. 



73. Molinia. 

 Panicle shining, dense and spike-like ; rachilla 



continuous. 77. Koeleria. 



Panicle open, the branches more or less spreading. 

 Rachilla continuous ; flowering scales deciduous in 

 fruit, the palet persistent. 



75. Eragrostis. 



Rachilla articulated ; flowering scales and palets 

 both deciduous with the rachilla internodes. 

 78. Catabrosa, 



