1018] 



The Grasses of Illinois 



367 



This species is a common weed in tlic West, but it has been reported 

 from only one locality in Illinois. 



DU PAGE CO. Napervillc, Uvihach, July, 1896 and 1898; Naperville, Moffatt, 

 Aug., 1894. 



Avena sativa L. 



This species is too well known to need description. Under cultiva- 

 tion the awn is obsolete, but in specimens found in waste places, it is 

 often fairly well developed. Such specimens may be distinguished 

 from A. fatua by the nearly glabrous lemma. 



CHAMPAIGN CO. Champaign, Clinton, July, 1900; Champaign, Seymour, July, 

 1880. COOK CO. Chicago, Lansing, July, 1898. lake ct). Channel lake, Eaynes, 

 Aug., 1905. PEORIA CO. Peoria, Brcndel. ST. clair co. Mascoutah, Welscli. 



183 



184 



186 



187 



188 



Figs. 183-188. — 183, D. caespitosa, spikelet ; 184, K. cristata, spikelet; 185, 

 -D. caespitosa, inflorescence; 186, A. fatua, spikelet; 187, A. elatius, inflorescence; 

 188, A. elatius, spikelet 



37. ARRHENATHERUM Beauv. 

 Oat Grass 



This genus is commonly called oat-grass on account of its spikelets, 

 which closely resemble those of the oat but are considerably smaller. 

 The plants are perennial with long, flat leaves and narrow panicles. 

 The spikelets are 2-flowered, one floret perfect, awnless or with a short 

 awn, the other staminate, awned, the awn bent, twisted near the base. 



Arrhenatherum elatius (L.) Beauv. 

 Tall Oat Grass. Eandall Grass (Figs. 187 and 188) 



Culms smooth, 3 to 4 feet tall ; sheaths smooth ; blades rough, 2 to 

 12 inches long, 2 to 8 mm. wide ; ligule membranous, about 1 mm. long, 

 panicle 4 to 12 inches long, narrow, the branches ascending ; spikelets 

 7 to 8 mm. long, the lemma rough, its awn about twice as long. 



