34 POALES 



den; Niobrara River; Thedford. 



16. Redfieldia. 128. 



1. Redfieldia flexuosa (Thurb.) Yasey. 



A common grass of the sand-hill regions. Antelope County; Box Butte 



County; Dismal River; Keya Paha; :\Iinden; Mullen; Thomas County; 



Valentine. 



17. Triplasis. 127. 



1. Triplasis purpurea (Walt.) Chapman. Sand Grass. 



In ravines in the sand-hills. Long Pine; Minden; Plummer Ford; 

 Rock County; Valentine. 



18. Tricuspis. 126. 



1. Tricuspis seslerioides (Michx.) Torr. 



Tridens flavus (L.) Hitchc. 

 In the eastern part of the state. Richardson County; Red Cloud; 

 Riverton; St. Paul. 



19. Phragmites. 125. 

 1. Phragmites phragmites (L.) Karst. Reed. 



Pliragmites communis Trin. 

 In wet places and in shallow water throughout the state. Albright; 

 Alliance; Halsey; Lincoln; Newark; Niobrara; North Platte; Pluni- 

 mer Ford; Valentine; Whitman. 



20. Munroa. 125. 

 1. IVIunroa squarrcsa (Nutt.) Torr. 



Common in the sand-hills, often in "blow-outs." Belmont; Callaway; 

 Crawford; Thedford; Valentine. 



Tribe 2 Hordeae. 

 With 1 spikelet at each joint of the rachis. 



Spikelets with their sides turned towards the rachis. 1. Agropyron. 

 Spikelets with their edges turned towards the rachis. 2. Lolium. 



With several spikelets at each joint of the rachis. 

 Spikelets 2-many flowered. 



Empty scales present forming an involucre around the cluster 

 of spikelets. 

 Rachis of the spike not readily breaking into joints, awns as- 

 cending or wanting, not widely spreading. 3. Elymus. 

 Rachis readily breaking into joints., awns of the empty scales 

 wide spreading. 4. Sitanion. 

 Empty scales wanting or rudimentary. 5. Hystrix. 

 Spikelets with but 1 fertile flower, lateral spikelets often rudimen- 

 tary and sterile. 6. Hordium. 

 1. Agropyron. 153 



No horizontal rootstocks or stolons, stems tufted. 

 Awns erect or none, spikelets nearly terete, approximate on the axis. 

 Awns usually as long as the scales. 



Spikes erect, 7-10 mm. wide, usually one-sided. 



1. A. richardsonil. 

 Spikes nodding, about 5 mm. wide. 2. A. caninum. 



Awns short or none. 



Spikes slender and lax, 7-20 cm. long, green. 3. A. tenerum. 



