68 PANICACExE. 



flat, or convolute-terete. Spikes solitary, on a terminal peduncle, 

 short or long, the clusters of spikelets on the Jointed rachis often 

 surrounded by a ring of hairs, Spikelets of the panicle sessile. 



There are 5 or 6 species dispersed over western and south- 

 western North America, 



The genus is readily recognized by each cluster consisting of 

 three spikelets, the central one containing a single fertile flower, 

 either pistillate or perfect, the two lateral ones staminate. 



A. Covered with short dense wool 1 



B. Not woolly . . . (b) 



b. Stoloniferous « 3 



b. Not stoloniferous 3, 4 



1. H. rigida (Thurb.) Scribner, Bull. Torr. Club, 9 : 33 (1884). 

 FleurapMs rigida Thurb, S, Wats, Bot. Calif. 2 : 293 (1880), 



Branching, 40-60 cm, high, covered with short, dense, white 

 wool. Ligule very short ; lower blades 10 cm. long, upper 2-3 

 cm. long, stiff, involute, bristly -pointed. Spike 7 cm. long, 7- 

 10 mm. wide, glumes and palea of the lateral spikes nearly equal ; 

 glumes of the terminal spikelets bifid, 3-nerved, 5-6 mm. long, 

 central nerve excurrent below the middle, the lateral nerves pro- 

 duced as setae ; floral glume 3-nerved; palea about equal to the 

 glume. 



California, Jones; Arizona, Lemynon for IT. S. Dept. Agricul. 

 412. 



2. H. cenchroides H. B. K. Nov. Gen. et Sp. 1117 (1815). 

 Culms 10-30 cm. high, stoloniferous, frequently rooting at the 



pubescent nodes, Ligule short, laciniate ; blades flat or involute, 

 narrow, 1-6 cm. long. Spikes 3-4 cm. long, Spikelets with dark 

 glands on the lower half. Outer empty glumes of the empty 

 spikelets about 5 cm. long, elliptical, 4-nerved, one vein becoming 

 a short awn, one-fourth of the distance from the apex; inner 

 em])ty glume shorter, with a longer awn ; floral glume and palea 

 nearly equal, hyaline, the former emctrginate, 1-nerved. Empty 

 glumes of the terminal florets 5-6-nerved, an awn extending half 

 its length above, near the base of which is a ligulate scale ; the 



