No. 10. 



HILARIA CENCHROIDES H. B. K., var. TEXAN A Vasey. 



Plant perennial. 



Rootstock none. Roots slender, branching. 



Stems of two kinds, (1) runners and (2) normal culms. Runners with 1 or 

 few nodes, producing a plant at each; internodes several inches long, slender, ter- 

 ete, glabrous. Culms erect, 6 to 12 inches high, slender, densely tufted from a 

 single rootstock, glabrous, retrosely long-villous at the nodes. 



Leaves of the stem 2 to 4; sheaths about 1 inch long, distant, tightly sheathing, 

 glabrous; blade to 1 line wide, seldom exceeding 3 inches in length, flat, scab- 

 rous above and on the margins, rarely beneath, otherwise smooth except sometimes 

 a few long hairs. Root-leaves similar, several on each stem, sheaths imbricated. 



Inflorescence a usually slender-pedunculate spike f to l inches long; rachis 

 flat, zigzag, minutely pubescent, spikelets inserted in clusters of 3 (resembling a 

 single spikelet) on opposite sides, contiguous or one-half overlapping. 



Spikelets 2% to 3 lines long, the parts spreading above. 



(1) MIDDLE SPIKELETS. 



Glumes 3; first and second, equal, similar, nearly as long as the spikelet, body 

 many-nerved, coriaceous below, scabrous, compressed, at the middle separating 

 into two linear obtuse spreading lobes becoming membranaceous-hyaline at the 

 apex, bearing in the fork an awn slightly exceeding the spikelet; third (flowering) 

 broadly oblong below, hyaline, 3-nerved, compressed, abruptly tapering from below 

 the middle into a slender compressed neck. 



Flower pistillate. Palet similar to the flowering glume but narrower and 

 2-nerved, and with it forming a cavity below and a neck above. Ovary and after- 

 ward the grain inclosed in this cavity. Styles long, lying in the neck, very slender 

 above; stigmas cylindrical, the body thick. 



(2) LATERAL SPIKELETS. 



Glumes 4; first similar to that of the middle spikelet, but inequilateral, and 

 with shorter awn; second similar to the first, but merely mucronate; third and 

 fourth each subtending a flower, alike, thin-membranaceous, lanceolate, hyaline, 

 1-nerved or with 1 or 2 additional lateral nerves. 



Flowers staminate. Palet thin-membranaceous, hyaline, 2-nerved, linear. 

 Stamens 3, anther narrowly linear. 



Grain inclosed primarily in its palet and glume, these becoming shining-coria- 

 ceous, the whole inclosed in the empty glumes, the entire cluster of spikelets 

 dropping off together. 



PLATE X; a, cluster of three spikelets; &, staminate flowers of one of the lateral 

 spikelets; c, pistillate flower of the middle spikelet. In b, one of the spikelets 

 should be sessile. In c, the stigmas are nearly twice too short and proportionally 

 too narrow, their bodies too slender, and the filaments not thick enough below. 



This species differs from the Mexican type in being more slender, with longer 

 culms, more spikelets in the spike, and the spikelets narrower and smooth instead 

 of scabrous. 



