| 1. Spikelet strongly compressed, glumes and lemmas clearly keeled |
| |
| 2. Lemma awn 03 mm; lower glume generally 57-veined |
| B. catharticus |
| 2' Lemma awn 315 mm; lower glume 37-veined |
| |
| 3. Annual; lemma body ± = upper glume, back glabrous to scabrous, short-hairy between outer 12 veins and margin |
| B. arizonicus |
| 3' Perennial; lemma body generally > upper glume, back evenly scabrous to short-hairy |
| |
| 4. Fruit compressed; lemma wing below middle and between outer vein and margin ± 1 mm wide; disturbed places |
| B. stamineus |
| 4' Fruit cylindric; lemma wing generally < 0.5 mm wide; ± undisturbed places |
| B. carinatus |
| 5. Spikelets not crowded or overlapping; branches and stalks generally > spikelets; generally inland |
| var. carinatus |
| 5' Spikelets crowded, overlapping; branches and stalks generally < spikelets; coastal |
| var. maritimus |
| 1' Spikelet subcylindric to compressed, lemmas (sometimes glumes) slightly compressed or with back rounded |
| |
| 6. Lemma awns generally 1555 mm, teeth generally 37 mm (except B. sterilis); lower glume generally 1-veined (except B. alopecuros) |
| |
| 7. Lemma awn bent, generally twisted 1+ × |
| |
| 8. Inflorescence dense; spikelets > lower branches or stalks; lemma teeth acute to rounded, not thread-like |
| 2 B. alopecuros |
| 8' Inflorescence ± open; spikelets generally < or = lower branches or stalks; lemma teeth thread-like |
| B. trinii |
| 7' Lemma awn generally straight, not bent, not twisted |
| |
| 9. Inflorescence dense; spikelets all ascending to erect, > lower branches or stalks |
| 2 B. madritensis |
| 10. Stem, leaf sheath generally glabrous; inflorescence narrowly ovoid to oblong; most spikelet stalks visible |
| subsp. madritensis |
| 10' Stem, leaf sheath generally puberulent; inflorescence ovoid; most spikelet stalks obscure |
| subsp. rubens |
| 9' Inflorescence generally open; lower spikelets (or branches) spreading to drooping, spikelets generally < lower branches or stalks |
| |
| 11. Lemma body 1830 mm, teeth 37 mm; awn 3055 mm |
| B. diandrus |
| 11' Lemma body 915 mm, teeth 03 mm; awn 830 mm |
| |
| 12. Lemma awn 1830 mm; 1° inflorescence branches generally with 1(2) spikelets |
| B. sterilis |
| 12' Lemma awn 818 mm; 1° inflorescence branches generally with 2+ spikelets |
| 2 B. tectorum |
| 6' Lemma awns generally 015 mm, teeth generally 03 mm; lower glume 13(5)-veined |
| |
| 13. Lemma awn bent to curved, teeth 34.5 mm |
| 2 B. alopecuros |
| 13' Lemma awn straight, generally erect, teeth 03(4) mm |
| |
| 14. Lemma awns generally < 3 mm |
| |
| 15. Glumes obtuse; lemma 23 mm wide (midvein to margin), body 69.5 mm; annual |
| B. briziformis |
| 15' Glumes acute to long-tapered; lemma 12 mm wide (midvein to margin), body 714 mm; perennial herb |
| |
| 16. Inflorescence generally nodding, lower branches drooping; upper glume 57-veined; glumes, lemmas puberulent |
| 3 B. anomalus |
| 16' Inflorescence erect, branches ascending to erect; upper glume 3-veined; glumes, lemmas generally glabrous |
| |
| 17. Plants from rhizomes; upper glume 610 mm, 12 mm > lower glume; lemma body 812 mm, awn 02.5 mm |
| B. inermis subsp. inermis |
| 17' Rhizomes 0; upper glume1013 mm, 23 mm > lower glume; lemma body 1014 mm, awn 25 mm |
| 2 B. suksdorfii |
| 14' Lemma awns generally 325 mm |
| |
| 18. Annual; lemma teeth generally 0.54 mm, acute |
| |
| 19. Lower glume 1-veined, upper glume 3-veined |
| |
| 20. Inflorescence dense; spikelets all ascending to erect, stalks generally < 10 mm |
| 2 B. madritensis (see 10. for subspp.) |
| 20' Inflorescence generally open, lower branches or spikelets spreading to nodding, stalks generally > 10 mm |
| 2 B. tectorum |
| 19' Lower glume 35-veined, upper glume 57-veined |
| |
| 21. Inflorescence ± dense; spikelets all ascending to erect, stalks generally 05 mm |
| B. hordeaceus |
| 21' Inflorescence open; lower spikelets spreading to nodding, some stalks or branches > 10 mm |
| |
| 22. Lemma body becoming hard, margins below middle inrolled, enclosing fruit; spikelet axis exposed in fruit |
| B. secalinus |
| 22' Lemma body ± membranous, margins touching, not inrolled, not enclosing fruit; spikelet axis concealed in fruit |
| |
| 23. Spikelet generally soft-hairy; lower glume 710 mm, upper glume 812 mm |
| B. arenarius |
| 23' Spikelet generally glabrous; lower glume 4.57 mm, upper glume 58 mm |
| B. japonicus |
| 18' Perennial; lemma tip generally rounded to minutely lobed |
| |
| 24. Inflorescence narrow, ± cylindric, interrupted, branches ascending to erect, generally < spikelets lower glume 1-veined, glabrous |
| 2 B. suksdorfii |
| 24' Inflorescence pyramidal, lower branches nodding to spreading, generally > spikelets |
| |
| 25. Lemma unevenly hairy, back generally glabrous above middle, puberulent below middle or between outer veins and margin |
| |
| 26. Lower glume 1(3)-veined, upper glume 3-veined; anthers generally 13 mm; ligule generally < 1.5 mm |
| B. ciliatus |
| 26' Lower glume 3-veined, upper glume 57-veined; anthers generally 34(5) mm; ligule generally 24 mm |
| 2 B. laevipes |
| 25' Lemma glabrous or evenly hairy throughout |
| |
| |
| 28. Upper glume 1015 mm; cauline leaf ligule generally 36 mm |
| B. vulgaris |
| 28' Upper glume 611 mm; cauline leaf ligule generally 13(4) mm |
| |
| 29. Lemma hairs generally > glume hairs, awn 13.5 mm; cauline leaf blades generally inrolled; sheath glabrous |
| 3 B. anomalus |
| 29' Lemma glabrous or hairs = glume hairs, awn 48 mm; cauline leaf blades generally flat; sheath glabrous to soft-hairy |
| 2 B. orcuttianus |
| |
| 30. Lemma hairs generally > glume hairs, awn 13.5 mm; cauline leaf blade generally inrolled |
| 3 B. anomalus |
| 30' Lemma and glume hairs generally ± equal, awn 38 mm; cauline leaf blade generally flat |
| |
| 31. Upper glume generally 5-veined |
| 2 B. laevipes |
| 31' Upper glume generally 3-veined |
| |
| 32. Inflorescence 1421 cm, lower branches nodding to spreading |
| B. grandis |
| 32' Inflorescence 617 cm, lower branches spreading to ascending |
| 2 B. orcuttianus
|