MANUAL OF THE GRASSES OF THE UNITED STATES 141 



4b. Panicle more or less open; spikelets usually more than 3 mm. long. 



5a. Spikelets sessile or nearly so 12. E. simplex. 



5b. Spikelets pediceled. 



6a. Spikelets mostly less than 5-flowered; lemmas obscurely nerved, scarcely 

 keeled. 

 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 de- 

 cumbent 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. TTNIOLOIDES. 



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



8a. Plants with glandular depressions on the panicle branches, the keel of 

 the lemmas, or on margins of blades or keel of sheaths. 

 Spikelets 2.5 mm. wide; glands prominent on keel of lemmas. Anthers 



0.5 mm. long 24. E. cilianensis. 



Spikelets not more than 2 mm. wide, mostly less; glandular depressions 

 mostly on panicle branches and leaves. 



Panicle narrow, rather dense 23. E. lutescens. 



Panicle open, at least one-fourth as wide as long. 



Spikelets 1.5 to 2 mm. wide, dark drab; panicle branches relatively 



stout and stiff 25. E. poaeoides. 



Spikelets about 1 mm. wide, pale; panicle branches slender, spread- 

 ing 17. E. perplexa. 



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 2 mm. long. 



22. E. ORCUTTIANA. 



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. 



26. E. BARRELIERI. 



Panicle open, often diffuse. 



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



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 primary 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 some- 

 times not overlapping; plants slender, mostly less than 30 

 cm. tall, the culms slender at base. Chiefly east of the 100th 



meridian 18. 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 Cali- 

 fornia 19. E. diffusa. 



Spikelets ovate to ovate-oblong, rarely linear, if linear not ap- 

 pressed along the primary panicle branches. 

 Plants comparatively robust, usually more than 25 cm. tall. 

 Texas to southern California. 

 Panicle large, the branches many-flowered, ascending or 

 drooping. Plant as much as 1 m. tall, with blades as much 

 as 1 cm. wide, but often smaller. 



27. E. NEOMEXICANA. 



Panicle smaller and more open, the spreading branches few- 

 flowered. Plant usually less than 30 cm. tall. 



28. E. MEXICANA 



