252 GRASSES OF IOWA. 



ternodes; ligule I line (i mm.) long or less; leaf blades I to 3 inches 

 (2-8 cm.) long; 1 to 2\ lines (2-5 mm.) wide. Spikelets 2 to i\ Lines 

 (4-5 mm.) long. 5 to 12-flowered, orbicular to deltoid ovate; empty 

 chimes 1 line (2 mm.) long; flowering glumes 1 to i-i lines (2-3 mm.) 

 long, scarious margined. May to July. See figure 175 on page 250. 



DISTRIBUTION. 



Iowa. Occasionally cultivated. 



North America. In fields and waste places from Ontario to Mass- 

 achusetts and Rhode Island. 



General. Great Britain, central Europe, Siberia and western 

 Asia. 



13. POA. 



Poa L. Sp. PI 1753. Endlicher. Gen. PL 98. Bentham & Hooker. 

 Gen. PI; 3: 1196. Hackel in Engler & Prantl. Nat. Pflanz. Fam. 11. 2: 

 73. /. 85. Beauv. Agros. 70. pi. 14. Scribner. Bull. U. S. Uept. Agr. 

 Div. Agros. 20: 148. /. 117. [Rev. Ed.]. Kunth. Rev. Gram. 150. pi. 83. 

 Steud. Syn. PL Glum. 1: 249. 



Pseudopoa Koch. Linn. 21: 409. 



Leucopoa Griseb. Ledeb. Fl. Ross. 4: 383. 1853. 



Poidium Nees. Lindl. Introd.'Nat. Syst. 450. 1835. (2 ed ) 



Dioicopoa E. Desv. in C. Gay. Fl. Chil. 6: 413. 



Spikelets ovate or lance-ovate, laterally compressed, several (2-10) 



flowered, in an open panicle. Empty glumes mostly shorter than the 

 flowers, the lower smaller; flowering glume membranaceo-herbaceous, 

 with a delicate, scarious margin, compressed-keeled, pointless, 5-nerved 

 (the intermediate nerves more obscure or obsolete) the principal nerves 

 commonly clothed with soft hairs at and toward the often cobwebby 

 base; palet membranaceous, two-toothed. Stamens 2 or 3. Stigmas 

 simply plumose. Grain oblong, free. Culms tufted, from perennial 

 roots; leaves smooth, usually flat and soft. (From the Greek name for 

 grass or fodder.) 



Bentham 5: Hooker give the number of species at 80; Hackel rec- 

 ognizes 100; Beal lists 43 species and 8 varieties; Heller gives 94 

 species and varieties. Some authors have extended the number to 200; 

 there can be no doubt that conservative botanists will reduce the num- 

 ber of species given for North America. The genus is widely diffused 

 over the temperate and cool regions in both hemispheres. They are 

 also common in Alpine and Arctic regions ; there are very few representa- 

 tives in the tropics. The] are excellent forage plants. 



