218 GRASSES OF IOWA. 



General. Northern Europe, north temperate and tropical Asia, 

 Africa, Australia, New Zealand, and in North America through Mexico 

 to Central America. 



3. TRIODIA. 



IriodiaR. Br. Prod. 182. 1810. Endlicher. Gen. PI. 98 Bentham & Hooker. 

 Gen. PI. 3: 1175. Hackel in Engler & Prantl. Nat. Pflanz. Fam. II. 2: 68. 

 Scribner. Bull. U.S. Dept. Agr. Div. Agros. 20: 128. /. 91. [Rev. Ed.] 



Sieglingia Bernh. Syst. Verz. P. fl. Erf. 40. 1800. Scribner. Bull. IJ. 

 S. Dept. Agr. Div. Agros. 20: 129. /. 98. [Rev. Ed.] 



Rhombolytrum Link. Hort. Berol. 2: 296. 



Tricuspis Beauv. Agrost. 77. pi. 15. f. 10. 



Windsoria Nutt. Gen. PI. N. Am. 1: 70. 



Uralepis Foura. Gram. Mex. 110. 



Jridena Roem. & Schult. Syst. 2: 240. 



Spikelets 3 to 12-flowered, somewhat terete, the rachis with 

 bearded joints; terminal flower abortive. Empty glumes unequal; 

 flowering glumes membranaceous or somewhat chartaceous, much larger 

 than the 2-toothed palet, convex, 2 to 3-toothed or cleft at the apex, 

 conspicuously hairy-bearded or villous on the 3 strong nerves, of which 

 the lateral are marginal or nearly so and usually excurrent, as is the mid- 

 nerve, especially, into a short cusp or awn. Stamens 3. Stigmas dark 

 purple, plumose. Grain oblong, nearly gibbous. Leaves taper-pointed, 

 sheaths bearded at the throat. Panicle simple or compound; the spike- 

 lets often racemose, purplish. (Name from the Greek words for three 

 and a tooth; alluding to the flowering glume.) 



Bentham & Hooker list 20 species, Hackel recognizes 2b. Widely 

 distributed throughout the temperate zones, and a few in tropical Amer- 

 ica. Nearly half the number of species occur in the United States, chiefly 

 in Texas and southwestern territories; Seal lists 16 species and 2 varieties 

 under Sieglingia. 



KEY TO THE SPECIES OF TRIODIA. 



Flowering glume 3-toothed by the excurrent nerves, usually with intermed- 

 iate, tooth-like lobes, appearing 5-toothed T. cuprea. l . 



Flowering glume 2-lobed, with the midnerve excur.ent, palea ciliate. 



— T. purpurea. a . 



1. TRIODIA CUPREA. 



Triodia cuprea Jacq. Eclog. Gram. 2: 1814. Watson and Coulter. 

 Gray. Man. Bot. 657. pi. 10. 1890. (6 ed.) Scribner. Grasses of 

 Tenn. Bull. Univ. Tenn. Agr. Exp. Sta. 7: 94. /. 122. 1896. 



