| 1. Glumes 0; top of stalk below lower floret ± knot-like, minutely hairy |
| E. californicus |
| 1' Glumes present, lanceolate to awl-like |
| |
| 2. Glumes awn- to awl-like, base generally < 1.5 mm wide, awn 25100 mm |
| |
| 3. Spikelets 3 per node; central spikelet fertile; lateral spikelets sterile, ± glume-like, florets vestigial |
| E. elymoides subsp. hordeoides |
| 3' Spikelets generally 2(3) per node; lateral spikelets with some fertile florets |
| |
| 4. Lower spikelets with 2 glumes; glumes entire |
| E. elymoides subsp. brevifolius |
| 4' Lower spikelets with 2 glumes and 1+ glume-like, reduced florets; glumes entire to divided into 2+ awns |
| |
| 5. Glumes divided into 3+ outward-curving awns; sheath appendages evident, 0.51.5 mm |
| E. multisetus |
| 5' Glume entire or divided into 2 outward-curving awns; sheath appendages obscure, < 0.5(1) mm |
| E. elymoides |
| 6. All glumes entire, awn generally < lemma awn |
| subsp. californicus |
| 6' Some glumes divided, awn(s) generally > lemma awn |
| subsp. elymoides |
| 2' Glumes flat, base generally > 1.5 mm wide, awn < 25 mm |
| |
| 7. Inflorescence with 24 spikelets at all or most nodes |
| |
| 8. Inflorescence nodding; glumes curving outward from base; base of lower florets exposed |
| E. canadensis |
| 8' Inflorescence erect; glumes not curving outward at base, base of lower florets concealed awns, if present, generally straight |
| E. glaucus |
| subsp. virescens |
| |
| 10. Leaf sheaths smooth or rough but not hairy |
| subsp. glaucus |
| 10' Leaf sheaths, blades sparsely to densely hairy, hairs spreading or directed downwards |
| subsp. jepsonii |
| 7' Inflorescence with 1 spikelet at all or most nodes |
| |
| 11. Lemmas awned, awns curving out at maturity |
| |
| 12. Spikelets 915 mm; inflorescence breaking apart at maturity |
| E. scribneri |
| 12' Spikelets 1018 mm; inflorescence not breaking apart at maturity |
| |
| 13. Stem 610 dm; leaf blade generally > 10 cm |
| E. arizonicus |
| 13' Stem 35 dm; leaf blade generally < 10 cm |
| E. sierrae |
| 11' Lemma awns straight or 0 |
| |
| E. lanceolatus subsp. lanceolatus |
| 14' Plants with tufted stems, rhizomes generally 0 |
| |
| 15. Anthers 36 mm; most inflorescence internodes > 15 mm |
| E. stebbinsii |
| 15' Anthers 12.5 mm; most inflorescence internodes < 15 mm |
| E. trachycaulus |
| 16. Lemma awn > lemma body, 830 mm |
| subsp. subsecundus |
| 16' Lemma awn < lemma body, < 7 mm |
| subsp. trachycaulus
|