10 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Plants less densely tufted; leaves flat, green, membranaceous. 

 Lemma indurated, not at all keeled. 



Spikelets 5 to 10-flo wered ; lemma awnless or rarely short 



awned. 

 Spikelets 3 to 6-flowered; lemma awnless. 



Glumes scarious-margined, much shorter than the 

 lemma; lemma not acuminate. 

 Lemma acute; spikelets loosely scattered. 

 Lemma obtuse; spikelets somewhat aggregated. 

 Glumes without scarious margins, nearly as long as 

 the lemma; lemma acuminate. 



Spikelets glaucous, loosely 4 to 6-flowered; lemma 



often with a short awn; sheaths smooth. 

 Spikelets green, closely 2 to 3-flowered; empty 

 glumes scabrous; sheaths short-pubescent. 

 Lemma awned, membranaceous, indurated only near the base 

 and keeled at least above the middle. 



Floret long-stipitate at base; awn terminal. 

 Floret not stipitate at base. 



Lemma plainly 5-nerved; awn from a cleft apex. 

 Spikelets 5 to 9 mm. long, 2 to 4-flo wered. 



Panicle branches ciliate; awn shorter than 



the lemma. 

 Panicle branches not ciliate; awn as long or 

 longer than the lemma. 

 Spikelets 10 to 15 mm. long, 3 to 7-flowered. 

 Lemma 5-nerved, the intermediate nerves very ob- 

 scure; awn terminal. 

 Awn much shorter than the lemma. 

 Awn as long as or longer than the lemma. 



Subgenus Hesperochloa. Perennials, densely tufted but pro- 

 ducing occasional stout extravaginal scaly stolons; leaf blades 

 broad, flat, or rarely involute; stamens 3, protruding; stigmas 

 elongate, the numerous short mostly simple branches arising from 

 all sides. 



A single species. 



Subgenus I. Vulpia (Gmel.) Hack. 



23. elatior. 



24. obtusa. 



25. shortii. 



26. versuta. 



27. johnsoni. 



28. subuliflora. 



29. dasyclada. 



30. elmeri. 



31. gigantea. 



32. fratercula. X 



33. subulata. 



34. confirm. 



Vulpia Gmel. Fl. Bad. 1 : 8. 1805, as genus. 



Vulpia Hack, in Engl. & Prantl, Nat. Pflanzenfam. 2^: 75. 1887, as subgenus. 



Annuals; stamens usually only 1, sometimes 3; florets usually remaining unopened, 

 and consequently self -pollinated; joints of the rachilla usually clavate; stigmas plu- 

 mose, the branches toothed, bilateral. 



Many of the species in this subgenus present slight but remarkably constant differ- 

 ences. In all probability this fact is connected with their close pollination. 





— LfJ.4^i^< 



