502 Key to the System of 



Fruit-supporting bracts seven- to eleven-streaked. 



Desert-plant, dwarf ; stems very thin, often purplish ; leaves 

 flat, narrow, lax ; membrane inside at the upper end 

 of the leaf-stalk conspicuous ; panicle small, slightly 

 spreading, few-branched ; spikelets much compressed, 

 mostly elliptic-ovate ; flowers several or few or occa- 

 sionally reduced to three ; fruit-supporting bract thin, 

 blunt, its keel ciliolated towards the base ; fruit very 

 slender. P. lepida. 



TRXODXA. 



2112. Tufts very large, with extremely pungent leaves. 



Desert-plant, with hardening base, often assuming a pale- or 

 dull-yellowish hue ; leaves numerous, very long and rigid, 

 straight, cylindrically convolute, the majority much 

 spreading ; panicle long but rather narrow ; spikelets 

 somewhat crowded ; fruit-supporting bract much streaked, 

 outside towards the base beset with short dense and 

 somewhat shining vestiture, terminated by three blunt 

 denticles; fruit loose within its bracts. "Porcupine- 

 Grass." T. irritans. 



TRXRAPHXS. 



2113. Panicle close and soft, its awns short, without any 



twist. 



Desert-plant, from quite dwarf to somewhat tall, rather 

 weak ; leaves simply acute, hardly involute along the 

 margin ; panicle often pale-green or purplish ; spikelets 

 very numerous, narrow, the lowest flowers fruit-bearing ; 

 fruit-supporting bract outside laxly beset with minute 

 hairlets and producing setular denticles between its awns, 

 the middle awn the longest ; fruit minute, narrow- 

 ellipsoid, loose within its bracts ; seed transparent. 



T. mollis. 



ELYTHROPHORUS. 



2114. Clusters of spikelets copiously pointed by the minute 

 setular awns. 



Annual, dwarf, erect; leaves flat; spikelets in the clusters 

 closely crowded, few-flowered, very short but compara- 

 tively broad ; fruit-bearing flower the lowest ; bracts all 

 narrow, gradually ending in their minute awn ; fruit- 

 supporting bract hardly extending beyond the lowest 

 bracts ; fruit loose within its bracts. E. articulatus. 



