GRASSES OF IOWA. 213 



The Fescues number 80 species, and the tribe takes its name from the 

 jrenus, Festuca. Orchard grass, Dactylis glomerata, is another well- 

 known example of this tribe. 



KEY TO THE GEXERA OF THE FESTUCEA.E. 



Plants dioecious. 



Flowering glume 3-nerved, subulate, finely awned. Tall, reed-like grass 



— Gynerium. ' . 

 Flowering glume 5-nerved, broad. Low meadow grass 



— Poa arachnifera. ,:i . 

 Plants not dioecious. 



Rachilla clothed with hairs, exceeding the glumes in length. Tall, 



aquatic reed Phragmites . s . 



Rachilla naked or its hairs much shorter than the flowering glumes. 



Flowering glumes 1-3-nerved .or rarely with faint, additional, interme- 

 diate nerves. 

 Flowering glumes membranaceous, seed not beaked or exserted. 

 Callus and lateral nerves of the flowering glumes hairy. 



Flowering glume tridentate or with the prolonged nerves 



mucronate between the teeth Triodia '■ . 



Flowering glume deeply 3-cleft, the lateral divisions very 

 narrow, the central produced into a fine awn. Triplasis. 4 . 

 Callus and lateral nerves of the flowering glume glabrous. 

 Empty glumes of the same shape. 



Panicle spike-like, shining Koeleria. 5 . 



Panicle more or less open and spreading. . .Eragrostis. 6 . 

 Empty glumes of different shape, the second broad and 



rounded at the apex Eatonia. ' '. 



Flowering glume coriaceous in fruit, seed beaked and exserted 



— Diarrhena . s . 

 Flowering glumes 5-many-nerved. 



Spikelets with two or more of the upper glumes empty, broad and 



enfolding each other Melica. '•'. 



Spikelets with the upper glumes fertile, or narrow and abortive. 



Glumes more or less strongly compressed and keeled, awn- 

 less or only awn-pointed. 



Spikelets broad, flat, in loose panicles, the 3-6 lower 



glumes empty, cultivated Uniola. >". 



Spikelets in one-sided clusters, flowering glumes herba- 

 ceous, awn-pointed, rough ciliate on the keel 



— Dactylis. ". 



Spikelets heart-shaped, in loose panicles, glumes 



roundish, ventricose, scarious margined. Cultivated. 



— Briza. 12 . 



Spikelets lanceolate or ovate lanceolate, small, in a 



rather loose panicle; flowering glumes scarious 



margined, mostly webbed at the base Poa. 13 . 



ijlumes rounded on the back, not keeled (or only in some 

 species of Bromus), awned in most of Festuca and Bromus. 



