GRASSES OF IOWA. 



309 



DISTRIBUTION. 



Iowa. Ames (Miss Sirrine, Pammel, Shepherd, Stewart). 

 North America. Introduced into Massachusetts, South Dakota 

 and Colorado (Ft. Collins, Pammel). 

 (/, neral. Europe. 



Fig. 223. Flower of Agropyron 

 ripens (after Gray.) 



TRIBE XII. HORDEAE. 



Spikelets one to many-flowered, usually 

 hermaphrodite, sessile along the common 

 rachis, forming a simple or compound 

 spike ; glumes awned or awnless. 



A small tribe of 20 genera and about 

 130 species. It is an important division, 

 however, for it includes rye, barley and 

 the many varieties of wheat. English and 

 Italian rye grasses are the chief meadow- 

 grasses of the tribe. 



KEY TO THE GENERA OF THE HORDEAE. 



A. Spikele's 1 at each joint of the rachis (sometimes more in Agropyron). 



1. Spikelets placed with one edge against the rachis; empty glume 1. 



— Lolium . ' . 



2. Spikelets placed with the flat side against the rachis; empty glumes 2. 



a. Flowering glumes with a distinct callus at the base, falling at 



maturity with the grain, which is adherent to the palea. 



— Agropyron.' 1 . 



b. Flowering glumes without a distinct callus, persistent grain 



free. 



(1) Empty glumes subulate, 1-nerved Secale. 3 . 



(2) Empty glumes lanceolate or ovate, 3-many-nerved. 



— Triticum.*. 



B. Spikelets 2-3 or more at each joint of the rachis. 



1. Empty glumes nearly as large as the flowering glumes. 



a. Spikelets 1-flowered, three at each joint; the lateral ones 



usually sterile Hordeum. 6 . 



b. Spikelets 1-several-flowered, 2-3 or more at each joint, all with 



perfect flowers Elymus. 6 . 



2. Empty glumes minute or wanting Asprella.' . 



1. LOLIUM. 



Lolium L. Sp. PI. 83 1753. Endlicher. Gen. PI. 103. Bentham and 

 Hooker. Gen. PI. 3: 1202. Hackel in Engler and Prantl. Nat. Pflanz. Fam. 

 II. 2: 77. Scribner. Bull. U. S. Dept. Agrl. 20: 159. /. 127. 



