340 GRASSES OF IOWA. 



let awned ; awn equalling those of the empty glumes. Florets of the 

 lateral spikelets awnless, or nearly so. April to August. 



Hordeum pusillum is an introduced plant, found at several points 

 in the southern half of the state, from Clinton to Council Bluffs. 



DISTRIBUTION. 



Iowa. Iowa City (Hitchcock) ; Marshalltown, Quarry (Ball) ; 

 Muscatine (Reppert) ; Council Bluffs, 1361 Ottumwa (Pammel) ; 

 Decatur County ( Fitzpatrick) ; Johnson County (Macbride, Hitchcock, 

 Shimek) ; Morning Sun (Carver) ; Lyon County, Davenport (Shimek) ; 

 Quarry 15 (Hodson) ; Steamboat Rock 3193 (Miss King) ; Iowa City 

 (Hitchcock); Decatur County (Shimek); Keosauqua (Shimek). 



North America. From Ontario to British Columbia; south to Illi- 

 nois (East St. Louis, Eggert), Nebraska (Grand Island, Crete, Mc- 

 Cook and Hastings, Pammel), Missouri (St. Louis, Pammel), Kansas 

 (Hitchcock), Texas (Nealley), Arkansas (Harvey), Colorado (Den- 

 ver and Ft. Collins, Pammel). 



6. ELYMUS. 



Elyj/ius L. Sp. PI. 83. 1753. Endlicher Gen. PI. 103. Bentham and 

 Hooker. Gen. PI. 3: 1206. Hackel in Engler and Prantl. Nat. Pflanz. Fam. 

 II. 2: 88./. 106. Scribner. Bull. U. S. Dept. Agrl. Div. Agros. 20: 166/. 

 134. 



Polyantherix Nees. Ann. Nat. Hist. 1:1. 284. 1838. 



Spikelets two to four at each joint of the rachis of a terminal spike, 

 all fertile and alike sessile, each one to seven-flowered. Glumes conspic- 

 uous, nearly side by side in front of the spikelets, two for each spikelet, 

 forming an involucre to the cluster. Flower coriaceous; the glume 

 rounded on the back, acute or awned at the apex. Grain adherent to 

 the involving glume (whence the name, an ancient one for some grain, 

 from the Greek word for to roll up). 



Bentham & Hooker recognize twenty species, including Sitanion, 

 while Hackel recognizes thirty species including the same genus. Beal 

 in his "Grasses of North America" recognizes fifteen species and three 

 varieties. 



KEY TO THE SPECIES OF ELYMUS. 



A. Spikes rigid, erect; empty glumes rigid, thick, indurated and strongly 

 curved at the base; awns 6-18 mm. long (or wanting in E. Virg'mi- 

 cus var. submuticus-) . 



1. Spikelets glabrous E. Virginicus , J . 



2. Spikelets hirsute E. hirsutiglumis. 3 . 



