GENERA OF GRASSES OF THE UNITED STATES. 83 



An erect tufted branching perennial, with oblong open panicles. 

 Species one; western Texas to southern Arizona and southward to 

 Argentina. 



Type 4 species: Cottcu pappophoroides Kunth. 



Cottea Kunth, Rev. Gram. 1: 84. 1829. A single species mentioned, from 

 Peru. 



This genus is allied to Pappophorum and very closely related to 

 Anthoschmidtia of Africa. It differs from the first in the several- 

 flowered spikelets that separate between the florets and in the awns 

 interspersed with awned teeth. Anthoschmidtia differs in having 

 glumes longer than the florets and in having lemmas with five awns 

 alternating with four lobes. 



Cottea pappophoroides Kunth (fig. 40) is not abundant enough to 

 have agricultural importance in the United States. Cleistogenes are 

 produced in the lower sheaths. 1 



32. PAPPOPHORUM Schreb. 



Spikelets 2 to 5 flowered, the upper reduced, the rachilla disarticu- 

 lating above the glumes but not between the florets, the internodes 

 very short; glumes nearly equal, keeled, thin-membranaceous, as long 

 as or longer than the body of the florets, 1 to several nerved, acute; 

 lemmas rounded on the back, firm, obscurely many nerved, dissected 

 above into numerous spreading scabrous or plumose awns, the florets 

 falling together, the awns of all forming a pappuslike crown ; palea 

 as long as the body of the lemma, 2-nerved, the nerves near the 

 margin. 



Erect, cespitose perennials, with narrow or spikelike tawny or 

 purplish panicles. Species 20, in the dry parts of the Old World, in 

 Australia, and from Texas to Argentina; 3 species in the United 

 States, from Texas to Arizona. 



Type species: Pappophorum alopecuroideum Vahl. 



Pappophorum Schreb. ; Vahl, Symb. Bot. 3 : 10. 1794. Only one species de- 

 scribed. 



Enneapogon Desv. ; Beauv., Ess. Agrost. 81, pi. 16, f. 11. 1812. Beauvois men- 

 tions Enneapogon desvauxii, Pappophorum gracile, P. nigricans, P. pallidum, 

 and P. purpurascens. The first one, being figured, is selected as the type. 



Polyrhaphis (Trin.) Lindl., Veg. Kingd. 115. 1847. Based on Pappophorum, 

 section Polyrhaphis Trin., under which a single species, P. alopecuroides Vahl, 

 is included. 



Pappophorum bicolor Fourn., with purplish, rather loose panicles, 

 is found in southern and western Texas ; P. vaginatum Buckl. (fig. 41) , 

 with pale, slender, spikelike panicles, and P. wrightii S. Wats. (fig. 

 42), with plumbeous short spikelike panicles and 9-nerved lemma, the 

 nerves extending into 9 equal plumose awns, are found from western 

 Texas to southern Arizona. Pappophorum wrightii produces cleis- 

 togamous spikelets in the lower sheaths. The cleistogenes are larger 

 than the normal florets, but the awns are almost wanting. As is the 



1 Chase, Amer. Journ. Bot. 5 : 256. 1918. 



