Agropyron 



HORDEAE 113 



Wabash River on the top of the first rocky bluff east of Georgetown or 

 about 6 miles west of Logansport. 



Newf. to s. Alaska, southw. to Pa., Ky., S. Dak., and Mont, and in the 

 mts. from B. C. to N. Mex. ; also in Siberia and Japan. 



31-335. TRIODIA R. Br. 



1. Triodia flava (L.) Smyth. (Tridens flavus (L.) Hitchc. of Gray, Man., 

 ed. 7 and Tridens flava (L.) Hitchc. of Britton and Brown, Illus. Flora, ed. 

 2.) Purpletop. Map 171. Infrequent to frequent or even locally common. 

 Possibly absent in a few counties where the soil is neutral and there are 

 no sandy areas. It prefers open, sandy soil; and it is usually most 

 abundant in prairie habitats. 



N. H. to Nebr., southw. to Fla. and Tex. 



32-335A. TRlPLASIS Beauv. 



1. Triplasis purpurea (Walt.) Chapm. Map 172. This species is local 

 in the dry sand of the dunes about Lake Michigan and common in a similar 

 habitat in Newton County about three miles northwest of Morocco where 

 it occurs in open sandy woods and fallow fields over an area at least 4 

 miles long and a mile wide (1938). 



N. H. to Minn., and Nebr., southw. to Fla. and Tex. 



j»_ 



3. HORDEAE Lindl. Barley Tribe 



Spikelets solitary at each node of the rachis (rarely 2 in species of Agropyron, but 

 never throughout) . 

 First glume (except in the terminal spikelet) lacking; spikelets placed edgewise to 



the rachis 47. Lolium, p. 120. 



First glume present; spikelets placed flatwise to the rachis. 



Glumes 1-nerved; spikelets with 2 perfect florets 42. Secale, p. 115. 



Glumes 3-many-nerved. 



Glumes lanceolate or linear; spikelets 3-many-flowered. . . 39. Agropyron, p. 113. 



Glumes ovate; spikelets 2-6-flowered 40. Triticum, p. 115. 



Spikelets 2-6 at each node of the rachis. 

 Spikelets all alike, 2-6-flowered. 



Glumes well developed, about as long as the florets, nerved ; spikes densely flowered, 



the spikelets mostly imbricated 43. Elymus, p. 115. 



Glumes obsolete or bristlelike, nerveless; spikes loosely flowered, the spikelets 



widely spreading 45. Hystrix, p. 118. 



Spikelets not all alike, (rarely 2- or 3-) 1-flowered, in 3's at each joint, the lateral pair 

 pedicellate, usually aborted 46. Hordeum, p. 119. 



39-405. AGROPYRON Gaertn. Wheatgrass 



Creeping rootstocks present; anthers about 4 mm long. 



Spikelets mostly 4-6-flowered, 9-17 mm long 1. A. repens. 



Spikelets mostly 7-12-flowered, 15-28 mm long 2. A. Smithii. 



Creeping rootstocks lacking; anthers about 1.5 mm long. 



Spikelets awnless or rarely a few with awns, the awns rarely up to 5 mm long 



3. A. pauciflorum. 



Spikelets all awned; awns usually all 6 mm long or longer 4. A. subsecundum. 



