176 



GRASSES OF IOWA. 



KEY TO THE SPECIES OF CALAMAGROSTIS. 

 Panicle open, the branches usually long and lax. 



Spikelets 2-2.5 mm. long C. Macouniana x . 



Spikelets 3-4 mm. long. 



Empty glrmes ovate-lanceolate, acute C. Canadensis} . 



Empty glumes sharp, attenuate-acuminate C. Canadensis, var. 



acuminata? . 

 Panicle contracted , branches short and strict C. xnexpansa* . 



1. CALAMAGROSTIS MACOUNIANA. 



Calamagrostis V* acouniana Vasey. Contrib. U. S. Nat. Herb. 3:81, 

 1892. Beal ^Grasses of N. A. 2: 

 343. 1896. Nash in Britton and 

 Brown. 111. Fl. 1: 163. f.372. 1896 

 Scribner. Bull. U. S. Dept. Agrl. 

 Diy. Agros. 17: 196./.^- 1896. 

 Deyeuxia M acouniana Vasey. 

 Coulter Bot. Gaz. 10:297. 1885. 



DESCRIPTION. 



Macoun's Reed Bent. A 

 slender, erect, leafy perennial, 

 from 1 to 2 feet (3-6 dm.) 

 high, with narrow, Hat leaves 

 and narrow or (in anthesis) 

 open, pyramidal panicles 3 to 4 

 inches (6-8 cm.) long. Spike- 

 lets with nearly equal empty 

 glumes, about \\ lines (3 mm.) 

 long, scarcely exceeding the 

 short-awned, flowering glume. 

 Moist, ' sandy soil. May to 

 August. 



DISTRIBUTION. 



Iowa. Emmet County 



(Cratty). 



North America. Assiniboia 

 to Missouri, Montana and 

 Washin-iton. 



Fig. 124. f Calamagrostis Macmmiana—a, 

 lower steiile glumes; b, floret with flowering 

 glume, and hairs; c, plumose prolongation of 

 rachilla. (Div. Agros. U. S. Dept.fAgrl. 1 



