MANUAL OF THE GRASSES OF THE UNITED STATES 



263 



Figure 356. — Sitanion han- 

 seni, X H- (Suksdorf 

 5237, Wash.) 



extensive collections shows that most of the characters used in differentiating 

 the forms are inconstant and combine in various ways. 



The species are widespread in the Western States but do not form com- 

 plete stands. They have forage value when young but at maturity the dis- 

 articulating joints of the spike, with their pointed rachis joints and long- 

 awned spikelets, are blown about by the wind and often cause injury to stock, 

 penetrating the mouth, nose, and ears, working in by means of the forwardly 

 roughened awns, and causing inflammation. Grazed also after the heads are 

 blown off. The commonest species is S. hystrix. 



Spike much longer than broad; glumes narrowly lanceolate, 2- to 4-nerved. 



o -i i i 1. S. HANSENI. 



fepike as broad as long or broader; glumes bristlelike, 1- or obscurely 2-nerved. 



Glumes cleft into at least 3 fine divisions 2. S. jubatum. 



Glumes entire or 2-cleft _ 3 # g # hystrix! 



1. Sitanion hanseni (Scribn.) J. 

 G. Smith. Hansen squirreltail. 

 (Fig. 356.) Culms 60 to 100 cm. tall; 

 sheaths and blades glabrous or sca- 

 brous to softly pubescent, the blades 

 flat to subinvolute, 2 to 8 mm. wide; 

 spike somewhat nodding or flexuous, 

 8 to 20 cm. long; glumes narrowly 

 lanceolate, sometimes bifid, 2- to 3- 

 nerved, long-awned, lower lemmas 

 about 8 mm. long, the awn 4 to 5 

 cm. long, divergent when dry and 

 mature. % — Open woods and 

 rocky slopes, Wyoming to eastern 

 Washington, Utah, and California. 

 Pubescent plants have been differen- 

 tiated as S. anomalum J. G. Smith. 

 (S. hanseni is said by Stebbins to 

 consist of a series of hybrids between 

 Elymus glaucus and Sitanion jubatum 

 or S. hystrix.) 



2. Sitanion jubatum J. G. Smith. 

 Big squirreltail. (Fig. 357.) Culms 

 erect to ascending, 20 to 60 cm. tall, 

 rarely taller; foliage glabrous or sca- 

 brous to white-villous, the blades flat, 

 often becoming involute, mostly not 

 more than 4 mm. wide; spike erect, 

 dense, 3 to 10 cm. long, thick and 

 bushy from the numerous long slen- 

 der spreading awns; glumes split into 

 3 or more long awns; lemmas mostly 

 8 to 10 mm. long, smooth, or scabrous 

 toward apex, the awns and those of 

 the glumes spreading, 3 to 10 cm. 

 long, rarely shorter. % — Rocky or 

 brushy hillsides and open dry woods 

 and plains, Idaho to eastern Wash- 

 ington, south to Utah, Nevada, Ari- 

 zona, and Baja California. Occasion- 



ally a few of the glumes in a spike are 

 divided into only 2 awns. Short- 

 awned plants have been differentiated 

 as S. breviaristatum J. G. Smith and 

 the more densely pubescent plants as 

 S. villosum J. G. Smith. 



3. Sitanion hystrix (Nutt.) J. G. 

 Smith. Squirreltail. (Fig. 358.) 

 Culms erect to spreading, rather stiff, 

 10 to 50 cm. tall; foliage from glabrous 

 or puberulent to softly and densely 

 white-pubescent, the blades flat to in- 

 volute, rather stiffly ascending to 

 spreading, 5 to 20 cm. long, 1 to 3 

 mm. wide, rarely as much as 5 mm. 

 wide; spike mostly short-exserted or 

 partly included, erect, 2 to 7 cm., 

 rarely 10 cm., long or longer, the 

 glumes very narrow, 1- to 2-nerved, 

 the nerves extending into scabrous 

 awns, sometimes bifid to the middle, 

 or bearing a bristle or awn along one 

 margin; lemmas convex, smooth or 

 scabrous to appressed pubescent, 

 sometimes glaucous, the awns of 

 glumes and lemmas widely spreading, 

 2 to 10 cm. long. % — Dry hills, 



