486 Key to the System of 



Spikelets often two-fruited, the outer bract about as 

 long as the next. 



Ascending, somewhat creeping or producing offshoots ; 

 leaves broad, often narrow-lanceolar, quite flaccid, flat ; 

 panicle spreading, almost capillarily branched ; spikelets 

 scattered, separately stalked, turgid, often in part dark- 

 colored ; all bracts blunt, the outer finely several-streaked ; 

 fruit -supporting bract slightly beset with very minute 

 hairlets. (Isachne Australis.) P, atro-virens. 



NEURACHNZi. 



2053. Lowest bract with an opening at the middle or towards 



the base. 



Desert-plant, never tall ; leaves short, broadish, usually 

 flat ; spike cylindrical, rather slender ; opening of the 

 lowest bract at its thickened upper margin conspicuously 

 beset with hairlets, at first membranously closed ; second 

 bract almost blunt; fruit finally dropping from the sup- 

 porting and the corering bract. N. Mitchelliana. 



Lowest bract without any opening ... ... ... 2054 



2054. Lowest bract closely ciliolated. 



Desert-plant, never tall ; leaves mostly narrow, somewhat 

 rigid ; spike ellipsoid- cylindrical, occasionally almost 

 globularly shortened, often assuming a somewhat dark 

 color ; lowest bract and the next gradually much pointed, 

 seven- to eleven-streaked, both conspicuously ciliolated ; 

 fruit finally dropping from the supporting and the 

 covering bract. N. alopecnroides. 



Lowest bract almost glabrous. 



Desert-plant, never tall ; leaves narrow, longitudinally in- 

 curved ; spike narrow-cylindrical, never dark-colored ; 

 lowest bract greenish, five-streaked, the next longer and 

 much more pointed, seven-streaked ; fruit finally dropping 

 from the supporting and the covering bract. 



TRAGUS. 



2055. Annual and relatively dwarf. 



Often of diffuse growth ; leaves flat, lax ; spike singly ter- 

 minal, somewhat raceme-like ; lowest bract rudimentary 

 or undeveloped ; second bract the largest, somewhat 

 pointed, bearing numerous minute hooked prickles ex- 

 teriorely ; fruit ellipsoid, free within its own thin bracts. 



T. racemosus. 



