120 



GRASSES OF IOWA. 



Tenn. Agrl. Exp. Sta. 7: 65. f. 77. 1894. Am. Grasses. Bull. 

 U. S. Dept. Agrl. Div. Agros. 17: 122. f. 418. 1899. Beal. Grasses 

 of N. A. 2: 202. 1896. Nash in Britton and Brown. 111. Fl. 1: 135. 

 f.303. 1896. Vasey Contr. U. S. Nat. Herb. 3: 46. 



Fig 8 I. Ariatida otigantha a. the lower or 

 empty glume; b, iiower witii widely spreading 

 awns. ( Div. Agros. U. S. Dept. Agrl. ) 



DESCRIPTION. 



Prairie Triple Awn. A 

 tufted annual, with slender 

 branching culms, 6 to 12 

 inches (15-30 cm.) high, nar- 

 row leaves, and loosely few- 

 tiowered racemes. Sheath? 

 smooth ; ligule a fringe of short 

 hairs; leaf-blade 2 to 6 inches 

 (5-15 cm.) long, involute, fili- 

 form, at least when dry. Pan- 

 icle racemose, four to six- 

 flowered. Spikelets 9 to 11 

 lines (18-22 mm.) long (ex- 

 clusive of the awns) ; empty 

 glumes three to five-nerved, 

 subequal, a little shorter than 

 the flowering glume, more or 

 less awn-pointed ; flowering 

 glumes scabrous, at least above, 

 three-awned,awns nearly equal, 

 or the lateral a little shorter, 

 divergent, 1 to 2 inches (2-5 

 cm.) long. Callus soft-hairy, 

 acute. Dry, gravelly or sterile 

 soil. Chiefly in southeastern 

 Iowa but also found locally in 

 the central portion. July to 

 October. 



DISTRIBUTION. 



Iowa. West Davenport, 130 (Barnes and Miller) ; Alt. Pleasant 

 ("Mills) ; Keokuk ( P. H. Rolfs) ; Ames (Pamrhel) ; Decatur County 

 (Fitzpatrick), Creston (Ashby). 



North America. New Jersey to Maryland, and west to Nebraska, 

 Iowa, Missouri (Eggert; Forest Park, Pammel ) , and south to Louis- 

 iana and Texas. 



