No. 40. 



TRIODIA TRINERVIGLUMIS (Munro) (Tricuspis trinerviglumis Munro 



in Herb.) 



Plant perennial, with slightly thickened tufted base. 



Culms erect or geniculate below, rarely branching, terete, hispid, 2 to 3 feet tall. 



Leaves; radical and of radical shoots numerous, with loose, pubescent sheaths 

 and involute, hispid, often pubescent blades, 3 to 6 inches long; of culm 4 to 6; 

 sheaths longer than internodes, open above, upper ones nearly smooth; blades like 

 those of radical leaves; ligule an inconspicuous fringe. 



Inflorescence a narrow, erect, spike-like panicle, 4 to 8 inches long; branches 

 erect, simple, almost appressed, \ to 2 inches long, or often reduced to single 

 spikelets a little distant, or interrupted. 



Spikelets oblong or oblanceolate, but little compressed, 7- to 9-flowered, 3 to 5 

 lines long; first glume lanceolate, obtuse or nearly acute, carinate, scarious, 7- 

 nerved, 2 to 3 lines long; second glume lance-ovate, acute, carinate, scarious, sca- 

 brid, hispid on keel, 3-nerved, 2| to 3-£ lines long; internode of rachilla stout, 

 pubescent, articulate above, i line long; floral glumes oblong-ovate, obtuse, emar- 

 ginate, mucronate or entire at apex, 3-nerved, pubescent below, lateral nerves 

 vanishing before reaching the margin, palet ovate, obtuse, pubescent on the 2 keels, 

 1-J lines long. 



Grain ovate-conical, deeply hollow on one side, dark-brown, punctate, 1\ lines 

 long. 



Plate XL; a, spikelet; b, and b', empty glumes; c, floral glume dorsal and 

 side views; d, and e, palet, ventral and side views. 



Prevails throughout Texas, westward to Arizona, and northward to Colorado. 

 Apparently not of great agricultural importance. Tricuspis mutica Torr. appears 

 to be a smaller form, with shorter, interrupted panicle. 



