Moist or wet meadows, in water on edge of lakes and in open woods, in N. M. 

 (Taos Co.) and Ariz. (Apache, Coconino and Gila cos.); Nfld. to Alas., s. to 

 the mts. of Md., w. to Wash, and Calif., s. to N. M. and Ariz. 



2. Agropyron Smithii Rydb. Western wheatgrass. 



Forming large colonies by means of slender fragile easily detached rhizomes, 

 the aerial culms erect even at the base; spikes strictly erect, rather dense, the 

 spikelets overlapping usually more than their lengths. Elymus Smithii (Rydb.) 

 Gould. 



In marshes and edge of water about lakes, along streams and ponds, oc- 

 casionally in flowing water, in Okla. (Cimarron Co.), abundant (formerly) in 

 the prairies of the higher parts of the Tex. Plains Country, infrequent e. to n.-cen. 

 Tex. and w. to the Trans-Pecos, N. M. (Grant and Colfax cos.) and Ariz. 

 (Apache, Navajo, Coconino, Yavapai and Pima cos.), late spring-summer; w. 

 U.S. e. to O., Ky., Tenn., Ark. and Tex. 



This species apparently tends to disappear under grazing. 



Var. molle (Scribn. & Smith) M. E. Jones has pubescent lemmas. 



Var. Palmeri (Scribn. & Smith) Heller has densely pubescent sheaths. 



3. Agropyron repens (L.) Beauv. Quackgrass. Fig. 95. 



Greep or glaucous; culms erect or curved at base, 5-10 dm. tall, sometimes 

 taller, with creeping yellowish rhizomes; sheaths of the innovations often pubes- 

 cent; blades relatively thin, flat, usually sparsely pilose on the upper surface, 

 mostly 6-10 mm. wide; spike 5-15 cm. long, the rachis scabrous on the angles; 

 spikelets mostly 4- to 6-flowered, 1-1.5 cm. long, the rachilla glabrous or scaberu- 

 lous; glumes 3- to 7-nerved, awn-pointed; lemmas mostly 8-10 mm. long, the 

 awn from less than 1 mm. to as long as the lemma; palea obtuse, nearly as long 

 as the lemma, scabrous on the keels. 



Waste places, meadows and pastures, also in seepage areas and wet meadows, 

 in N. M. (Otero and Taos cos.) and Ariz. (Coconino Co.) Nfld. to Alas., s. 

 to N.C., Ark., Ut. and Calif.; Mex.; introd. from Euras. 



A troublesome weed in cultivated ground. 



17. Elymus L. Wild-rye 



Perennials; culms slender; minute pointed auricles present at juncture of blade 

 and sheath; inflorescence a terminal spike, the axis slender with short internodes, 

 remaining intact; spikelets collaterally paired at each node, each basally only 

 slightly laterally compressed and with one side toward the axis but each distally 

 (due to contortion of rachilla) with 1 keel toward the axis; spikelets 2- to 6- 

 flowered, all the flowers perfect except the terminal 1 or 2; glumes equal, firm 

 to subindurate, lanceolate to subulate, 1- to several-nerved; lemmas lanceolate, 

 cymbiform, not keeled, eventually subindurate, obscurely 5-nerved, awned from 

 the tip in most species. 



A genus of about 70 species in temperate North America and South America. 



1. Rhizomes present; awns of lemmas 0-2 mm. long 1. E. triticoides. 



\. Rhizomes absent but base of culm usually decumbent; awns of lemmas 5-45 



mm. long (2) 



2(1). Glumes basally discolored, indurate, roundish in transection and diverging 

 from the axis at a large angle, becoming broader and flatter toward 

 the middle and then tapering to the awn 2. E. virginicus. 



2. Glumes basally flat, neither discolored, indurate nor rounded, diverging at 



a low angle, broadest near the base and tapering the full length to 

 the awn 3. E. canadensis. 



210 



