466 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



appressed to the axis, in terminal spikes. Type species, Hilaria 

 cenchroides H.B.K. Named for Auguste St. Hilaire. 



All the species are important range grasses. Curly mesquite is the 

 dominant "short grass" of the Texas plains. The larger species are 

 well known on the range in the arid and semiarid regions of the 

 Southwest. They resist close grazing. 



Culms white felty pubescent 4. H. rigida. 



Culms not felty pubescent. 



Cluster of spikelets not flabellate; glumes of lateral spikelet narrowed toward 



summit-. 3. H. jamesii. 



Cluster of spikelets flabellate; glumes (at least the outer one) of lateral 

 spikelets broadest toward summit. 

 Glumes subhyaline and fimbriate at summit; plants tufted, not stoloni- 



ferous 2. H. mutica. 



Glumes firm, not fimbriate; plants stoloniferous (except in var. longi- 



folia) 1. H. BELANGERI. 



1. Hilaria belangeri (Steud.) Nash. 

 Curly mesquite. (Fig. 1002.) 

 Plants in tufts, sending out slender 

 stolons, these producing new tufts, 

 the internodes of the stolons wiry, 5 

 to 15 cm long; culms erect, slender, 10 

 to 30 cm tall, villous at the nodes; 

 blades flat, curly, 1 to 2 mm wide, 

 usually short, crowded at base, form- 

 ing a curly tuft, but sometimes longer 

 and erect; spike usually 2 to 3 cm 

 long, with mostly 4 to 8 clusters of 

 spikelets, the axis flat, the internodes 

 alternately curved, 3 to 5 mm long; 

 group of spikelets 5 to 7 mm long; 

 lateral spikelets attenuate at base, 

 the glumes united below, firm, sca- 

 brous, the outer lobe broadened up- 

 ward, 2- to 3-nerved, the inner much 

 reduced, the midnerve of both glumes 

 extending into short awns, the first 

 glume smaller, the lateral nerves some- 

 times excurrent into awns or teeth (the 

 glumes variable in a single spike); 

 fertile spikelet usually shorter than the 

 sterile, rounded at base; glumes firm 

 with deeply lobed thinner upper part, the midnerves extending into 

 awns mostly exceeding the staminate spikelets; lemma compressed, 

 narrowed above, awnless. % (H. texana Nash.) — Mesas and plains, 

 Texas to Arizona and northern Mexico. H. cenchroides H.B.K. , to 

 which this species has commonly been referred, is confined to Mexico. 

 Hilaria belangeri var. longifolia (Vasey) Hitchc. Stolons want- 



Figure 1003.— Hilaria mutica, X 1. (Tou- 

 rney, Ariz.) 



ing; blades 



elongate. 



91 (H. longifolia Vasey.) — Arizona and 



Sonora. 



2. Hilaria mutica (Buckl.) Benth. Tobosa grass. (Fig. 1003.) 

 Culms from a tough rhizomatous base, 30 to 60 cm tall, glabrous, the 

 nodes pubescent; blades flat or somewhat involute, rather rigid, 2 to 3 

 mm wide; spikes 4 to 6 cm long; group of spikelets about 7 mm long; 

 bearded at base; glumes of lateral spikelets very unsymmetrical, 



