220 A TEXT-BOOK OF GRASSES 



c. Plants dioecious; sexes unlike, the pistillate 

 lemmas long-awned, th(; staminate awn- 

 less or nearly so; southwestern states 



(burro-grass) Scleropogon. 



cc. Plants perfect; lemmas broad, o-lobed; 

 spikelets in racemes; annuals. Cali- 

 fornia Orcuttia. 



A A. Lemmas awnless or with 1 terminal awn, this 



sometimes from between 2 teeth (more or 



less 3-toothed in Tridens). 



B. Rachilla or lemma with hairs as long as the 



lemma (only the pistillate in Cortaderia); 



tall reeds with large terminal plume-hke 



panicles. 



c. Plants dioecious, the staminate spikelets 



naked; blades narrow .Cortaderia 



cc. Plants perfect; blades broad. (Par. 246). 



D. Lemmas hairy; rachilla naked Arundo 



(Par. 247). 



DD. Lemmas naked; rachilla hairy Phragmites. 



BB. Rachilla and lemmas naked or pubescent, not 

 with long hairs. 

 c. Plants dioecious. 



D. Plants low and creeping; spikelets 

 obscure, scarcely differentiated from 

 the short crowded rigid leaves; mud 

 flats along coast. Florida and Cali- 

 fornia MONANTHO 



DD. Plants erect from creeping rhizomes; [chloe. 



inflorescence a narrow simple exserted 



panicle Distichlis 



cc. Plants not dioecious (except a few species (Par. 249). 



of Poa). 

 D. Spikelets of 2 forms, sterile and fertile 

 intermixed. 

 E. Fertile spikelets 2- to 3-flowered; ster- 

 ile spikelets with numerous awned 

 glumes; our species perennial (C 

 cristatus L., crested dog's-tail, occa- 

 sionally sown in mixtures for 



meadows) Cynosurus. 



EE Fertile spikelets 1-flowered, long- 

 awned; sterile spikelets with many 

 obtuse glumes; annual {A. aureum 

 (L.) Kuntze, Lamarckia aurea 

 Moench, golden top, occasionally 

 cultivated for ornament, commonly 



introduced on the Pacific coast) Achyrodes. 



DD. Spikelets all ahke. 



