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



Panicles two- thirds the entire length of the plant or more, diffuse; 

 pedicels more than 5 mm long; culms erect, closely tufted. 



14. E. CAPILLARIS. 



Panicles less than half the entire length of the plant, oblong, open 

 but scarcely diffuse; pedicels mostly less than 5 mm long; culms 



spreading or decumbent at base 15. E. frankii. 



6b. Spikelets mostly more than 5-flowered. 



7a. Spikelets ovate to oblong, flat, the florets spreading, closely 



imbricate 13. E. unioloides. 



7b. Spikelets oblong to linear, the florets appressed. 



8a. Plants with minute glandular depressions on the branches 

 and often on the keels of the lemmas. 

 Lemmas not glandular on the keel. 



Panicle narrow, rather dense, the branches with scattering 



glandular depressions 22. E. lutescens. 



Panicle open, the branches and pedicels widely spreading, 

 the latter with a glandular depression below the spikelet. 



28. E. SUAVEOLENS. 



Lemmas glandular on the keel. 



Spikelets 2.5 to 3 mm wide; panicle usually rather dense; 



anthers 0.5 mm long 23. E. cilianensis. 



Spikelets about 1.5 mm wide; panicle open; anthers 0.2 



mm long 24. E. poaeoides. 



8b. Plants not glandular on the branches nor lemmas, sometimes 

 glandular on the sheaths (E. neomexicana) and below the 

 nodes (E. barrelieri). 

 Spikelets about 1 mm wide, linear, slender. 



Plant delicate; spikelets 3 to 5 mm long; lemmas 1 to 1.5 



mm long 16. E. pilosa. 



Plant rather stout; spikelets 5 to 7 mm long; lemmas about 



2mmlong 21. E. orctjttiana. 



Spikelets 1.5 mm wide or wider, ovate to linear. 



Panicle narrow, the branches ascending, spikelet-bearing 

 nearly to base, few-flowered; spikelets linear, mostly 



10- to 15-flowered 25. E. barrelieri. 



Panicle open, often diffuse. 



Spikelets linear, mostly 8- to 15-flowered, on slender spread- 

 ing pedicels mostly longer than the spikelets. 



29. E. arida. 

 Spikelets ovate to linear, if linear not on spreading 

 pedicels. 

 Spikelets linear at maturity, appressed along the pri- 

 mary panicle branches, these naked at the base for 

 usually 5 to 10 mm. Lower lemmas 1.5 mm long. 

 Primary panicle branches simple or the lower with a 

 branchlet bearing 2 or 3 spikelets; spikelets 

 loosely imbricate or sometimes not overlapping; 

 plants slender, mostly less than 30 cm tall, the 

 culms slender at base. Chiefly east of the 100th 



meridian 17. E. pectinacea. 



Primary panicle branches usually bearing appressed 

 branchlets with few to several-spikelets, the 

 spikelets thus appearing imbricate or crowded 

 along the primary branches; plants more robust, 

 mostly more than 30 cm tall, the culms stouter 

 at the base. Chiefly from Texas to southern 



California 18. E. diffusa. 



Spikelets ovate to ovate-oblong, rarely linear, if linear 

 not appressed along the primary panicle branches. 

 Plants comparatively robust, usually more than 25 

 cm tall. Texas to southern California. 

 Panicle large, the branches many-flowered, ascend- 

 ing or drooping. Plant as much as 1 m tall, 

 with blades as much as 1 cm wide, but often 



smaller 26. E. neomexicana. 



Panicle smaller and more open, the spreading 

 branches few-flowered. Plant usually less 

 than 30 cm tall 27. E. mexicana. 



