MANUAL OF THE GRASSES OF THE UNITED STATES 



449 



FIGURE 956. Distribution of 

 Aristida adscensionis. 



16. Aristida barbata Fourn. HAVARD THREE-AWN. (Fig. 959.) 

 Perennial, forming hemispherical tufts as much as 30 cm in diameter, 



the culms rather stiffly radiating in all 

 directions, 15 to 30 cm long; blades 

 closely involute, mostly less than 10 

 cm long and 0.5 mm thick; panicles 

 about half the length of the entire 

 culm, open, the branches divaricately 

 spreading or somewhat reflexed, 

 mostly 3 to 6 cm long, in pairs or 

 with short basal 

 branchlets, but 

 without long 

 naked base, the 

 branchlets and 

 pedicels impli- 

 cate or flexuous, 

 the whole pan- 

 icle fragile at maturity, breaking away 

 and rolling before the wind ; glumes 

 about equal, 1 cm long; lemma grad- 

 ually narrowed into a straight or 

 twisted scaberulous beak, the entire 



FIGURE 955. Aristida adscens ionis, X 1. (Earle length 8 to 10 mm; awns SOHie- 



559, N.Mex.) what divergent, nearly equal, 15 to 



20 mm long. 91 (A. havardii Vasey.) Hills and plains, western 

 Texas to Arizona and central Mexico. 



17. Aristida divaricata Humb. and Bonpl. POVERTY THREE-AWN. 

 (Fig. 960.) Perennial; culms erect or 

 prostrate-spreading, usually 30 to 60 cm 



long, sometimes longer; blades flat or 

 usually loosely involute, or the basal 



closely involute, 



mostly less than 3 



mm wide; panicle 



large, diffuse, usu- 

 ally as much as 



half the entire 



length of the culm, 



the branches 



spreading or reflexed, naked below; 

 glumes nearly equal, 1 cm long; lemma 



1 cm long, narrowed into a twisted beak 



2 to 5 mm long; awns about equal, 10 

 to 15 mm long. 91 Dry hills and 

 plains, Kansas to southern California, 

 south to Texas and Guatemala (fig. 961). 



18. Aristida hamulosa Henr. (Fig. 

 962.) Resembling A. divaricata; lemma 

 somewhat narrowed at summit but not 

 twisted, central awn a little longer than 

 the two lateral ones. 9[ Dry hills 



and plains, western Texas to southern California, south to Guatemala 

 (fig. 963). In Arizona more common than A. divaricata. 



FIGURE 958. Distribution of 

 Aristida intermedia. 



ll 



FIGURE 957. Aristida intermedia, X 1. 

 (Kearney 236, Miss.) 



