142 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Plants delicate, mostly less than 25 cm. tall; blades mostly not 

 more than 2 mm. wide (see also E. frankii var. brevipes). 

 Panicle lax, the branches usually naked at base; spikelets 



4 to 7 mm. long 20. E. tephrosanthos. 



Panicle rather stiff, the branches often floriferous nearly to 

 the base; spikelets mostly not more than 3 mm. long. 



21. E. MULTICAULIS. 



lb. Plants perennial. 



9a. Panicle elongate, slender, dense, spikelike 6. E. spicata. 



9b. Panicle open or contracted, not spikelike. 



10a. Plants with stout scaly rhizomes 1. E. obtusiflora. 



10b. Plants without rhizomes. 



11a. Spikelets subsessile or nearly so, the lateral pedicels not more than 1 mm. long. 

 Spikelets subsessile, distant along the few stout panicle branches. 



2. E. SESSILISPICA. 



Spikelets short-pediceled. 



Panicle large, becoming a tumbleweed, the axis and branches viscid. 



3. E. CURTIPEDICELLATA. 



Panicle narrow (sometimes open in E. oxylepis), not a tumbleweed nor viscid; 

 keels of palea forming a thick white band; grain 1 to 1.2 mm. long. 

 Lemmas 3 mm. long, somewhat abruptly narrowed to the acute apex; panicle 



usually red brown; anthers 0.2 to 0.3 mm. long 4. E. oxylepis. 



Lemmas 3.5 mm. long, tapering to the acuminate apex; panicle pale or slightly 



pinkish; anthers 0.4 to 0.5 mm. long 5. E. beyrichii. 



lib. Spikelets with pedicels more than 1 mm. long (appressed along the branches in 

 E. refracta; sometimes scarcely more than 1 mm. long in E. chariis and E. 

 bahiensis). Panicles large and open (sometimes condensed in E. bahiensis). 

 12a. Nerves of lemma obscure; lemma rounded on back, sometimes slightly keeled 

 toward apex. 

 Axils of main panicle branches usually strongly pilose (rarely glabrous in E. 

 intermedia). 

 Sheaths pilose or hirsute (sometimes glabrous in E. hirsuta). 



Culms mostly more than 50 cm. tall; blades elongate, flat, not crowded at 



base of culm 30. E. hirsuta. 



Culms mostly less than 50 cm. tall; blades rather short and crowded at 



base of culm 32. E. trichocolea. 



Sheaths glabrous or nearly so, except the pilose summit. 



Spikelets about 1 mm. wide, 3- to 7-flowered, 3 to 5 mm. long; lemmas 1.3 



to 1.5 mm. long 31. E. ltjgens. 



Spikelets about 1.5 mm. wide; 3- to 8-flowered, 3 to 10 mm. long; lemmas 



1.8 to 2 mm. long 35. E. intermedia. 



Axils of main panicle branches glabrous or the lower sparsely pilose. 



Pedicels bearing above the middle a glandular band or spot; axils glabrous. 



36. E. SWALLENI. 



Pedicels without glandular band; lower axils sparsely pilose to glabrous. 



Lemmas about 3 mm. long 33. E. erosa. 



Lemmas about 2 mm. long 34. E. palmeri. 



12b. Nerves of lemma evident, usually prominent; lemmas keeled. 

 Spikelets approximate in a somewhat condensed panicle, or along the main 

 branches of a somewhat spreading panicle; florets mostly 15 to 30. 

 Panicle branches distant, glabrous or nearly so in the axils. 



Paleas readily deciduous 45. E. chariis. 



Paleas persistent 46. E. bahiensis. 



Panicle branches approximate, villous in the axils. Culms densely cespitose 

 with arcuate blades attentuate to long filiform flexuous tips. 



47. E. CURVULA. 

 Spikelets in an open panicle. 



Panicle longer than broad, the branches not horizontally spreading. 

 Culms not more than 60 cm. tall. 

 Spikelets 9- to 15-flowered; panicle less than one-third the entire length of 



culm, the branches not viscid 37. E. tracyi. 



Spikelets 4- to 8-flowered; panicle more than half the entire length of culm, 



the branches viscid 38. E. silveana. 



Culms usually 1 m. or more tall. 



Spikelets mostly not more than 6-flowered, purplish. 



39. E. TRICHODES. 



