194 



GRASSES OP IOWA. 



TRIBE X.— CHLORIDEAE. 



Spikelets I to several-flowered, 

 in one-sided spikes or racemes; 

 the racemes digitate or fascicu- 

 late rarely solitary; flowering 

 glumes usually keeled, entire and 

 unawned, or toothed, and with i 

 to 3 (rarely more than. 3) 

 straight awns. 



A small tribe of 27 genera and 

 155 species, characterized chiefly 

 by the inflorescence, which is 

 nearly that of Pas pal urn. The 

 awns, when present, are not dorsal 

 or twisted, as in the Agrostideae 

 and Avencae. Chiefly natives of 

 tropical and subtropical coun- 

 tries; a few are widely distrib- 

 uted as weeds throughout the 

 warmer parts of the world. A 

 number are good turf-forming 

 grasses and are valued for graz- 

 ing purposes. One of these is 

 the celebrated buffalo grass of the 

 western plains, which is remark- 

 able for having the staminate 

 and pistillate spikelets separate 

 and in unlike inflorescences, either 

 upon the same plant (monoeci- 

 ous) or upon different plants 

 (dioecious). Bermuda grass, and 

 the Gramas of the southwest be- 

 long to this tribe. 



Fig. 137. Flower of Sparlina cynosur- 

 oides. (after Gr;>v. i 



Fig. 138. Flower of Bouteloua curtipendula. 

 (after Gray. ) 



KEY TO THE GENERA OF THE CHLORIDEAE. 



Flowers perfect. Spikelets all alike. 

 One perfect flower in each spikelet. 



No sterile glumes above the flower. 



Spikes digitate, slender; a creeping perennial. . .Cynodon.^ . 

 Spikes racemose. 



Spikelets globose Beckttianniar. 



Spikelets lanceolate. 



Spikes thick, pectinate; stout, erect perennials 



— Spartina} . 

 Spikes slender; low, diffuse annuals 



— Schedonnardus . 4 . 



