No. 22. 
TRISETUM INTERRUPTUM Buckley. 
Plant slender, tufted, annual, rather glaucous throughout. 
Roots numerous, fine. 
Culms ascending, geniculate, branching, terete, smooth, 6 to 18 inches tall. 
Leaves of radical shoots numerous, with smooth or cinerous-pubescent sheaths 
and fiat blades, hispid above, 2 to 3 inches long; of culm 3 to 5; sheaths usually 
little shorter than internodes, smooth or somewhat scabrous or pubescent; blades 
flat or involute, scabrous, 2 to 3 inches long; ligule membranaceous, lacerate, 
obliquely truncate, 1 line long. cap 
_ Inflorescence a narrow, somewhat interrupted, erect or flexuous panicle, 3 to 
5 inches long; branches in 2’s or 3’s of unequal length, $ to 1 inch long. 
Spikelets sessile, obovate, 3- to 4-flowered, upper orie sterile or small and abor- 
tive, 2 to 24 lines long; first glume oblanceolate, acute, herbaceous, hispid on 
keel, 3-nerved, 14 to 2 lines long; second glume same, but twice as wide and 
5-nerved; internode of rachilla curved, glabrous, $ line long; floral glume lanceo- 
late, rounded on back, scarious above, rigid, smooth, about 2 lines long, 3-nerved, 
ending in 2 slender teeth, 2 lateral nerves uniting above with the midnerve and 
forming above the middle a slender hispid awn, 2 to 3 lines long; palet narrowly 
linear, wider at top, lanceolate when spread out, thin, smooth, 2-keeled, cleft at— 
apex, standing out of floral glume, 1 line long. te ae aa 
Grain yellowish, opaque, elliptical, flattened, 1 line long. 
‘PLatTE XXII; a, floral glume, side view; b, palet; ce, spikelet; d (marked a in 
plate), empty glumes. The floral glume, a, is not well figured, as 
Abundant in Texas, 
