Jepson eFlora
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Key to Bromus

View taxon page for Bromus

1. Spikelet strongly flattened; lemma strongly keeled (sect. Ceratochloa)

2. Lemma awn 0–3.5 mm; lemma veins prominent ..... B. catharticus var. catharticus

2' Lemma awn 4–15 mm; lemma veins obscure or prominent

3. Some lower inflorescence branches > 10 cm, spreading to nodding ..... B. sitchensis

3' Lower inflorescence branches < 10 cm, or if longer, erect to ascending

4. Upper glume ± = lowermost lemma

5. Annual; lower glume 3–5-veined, upper 9–15 mm, 5–9-veined; lemma 7–veined, margin generally hairy (occasionally glabrous), backs hairy or glabrous, awn 7–15 mm; anthers <= 0.5 mm ..... B. arizonicus

5' Perennial herb; lower glume 5–7(9)-veined, upper 11–20 mm, 7–9-veined; lemma 9–11-veined, generally hairy at least distally, awn 6–12 mm; anthers 0.6–1 mm ..... B. catharticus var. elatus (2)

4' Upper glume generally < lowermost lemma — lemma scabrous or variously hairy, marginal hairs if present similar in length to those on back

6. Inflorescence dense, pedicel generally < spikelets; spikelets crowded, overlapping, stalks not visible; stem 20–80 cm, occasionally bent at base; stem, leaves glabrous or occasionally scabrous; ligule <= 6 mm ..... B. maritimus

6' Inflorescence loose to compact, at least some pedicels > spikelets; spikelets not crowded or overlapping, stalk often visible; stem 30–120 cm, erect; stem, leaves often hairy; ligule generally < 4 mm

7. Most awns >= (6)7 mm

8. Lemma generally uniformly hairy, occasionally scabrous, veins 7, obscure ..... B. carinatus var. carinatus

8' Lemma generally hairy at least distally, veins 9–11 on distal 1/2, prominent ..... B. catharticus var. elatus (2)

7' Most awns < 7 mm

9. Sheath throat and/or lemma hairy ..... B. carinatus var. marginatus

9' Sheath throat, lemma glabrous ..... B. polyanthus

1' Spikelet not strongly flattened; lemma rounded over midrib and not strongly keeled

10. Lemma tip conspicuously 2-toothed, teeth translucent, awn-like to acuminate, 1–7 mm; largest lemmas generally < 2 mm wide

11. Lemma awn bent and/or twisted (sect. Neobromus) ..... B. berteroanus

11' Lemma awn straight, not twisted (sect. Genea)

12. Lemma mostly > 20 mm; awn 30–65 mm ..... B. diandrus

12' Lemma mostly < 20 mm; awn 8–30 mm

13. Inflorescence dense, branches erect to ascending ..... B. madritensis

14. Inflorescence branches occasionally > spikelets, shortest branch on lowest inflorescence node 6–24 mm, longest branch on lowest node 0–1 × branched; sterile florets <= 3; inflorescence internodes gradually reduced upwards; florets not overlapping at maturity ..... subsp. madritensis

14' Inflorescence branches < spikelets, shortest branch on lowest inflorescence node <= 6 mm, longest branch on lowest node 2–5 × branched; sterile florets 3+; inflorescence internodes abruptly reduced upwards; florets overlapping at maturity ..... subsp. rubens

13' Inflorescence open, branches spreading to nodding

15. Spikelets 1(3) per inflorescence branch; inflorescence generally simple; branches > spikelets (< when inflorescence reduced to 1(3) spikelets); lemma 13–20 mm; awn 15–30 mm ..... B. sterilis

15' Spikelets 1–14 per inflorescence branch; inflorescence branched 1–5 ×; branches < or > spikelets; lemma 9–13 mm; awn 8–18 mm ..... B. tectorum

10' Lemma tip entire or inconspicuously 2-toothed, teeth generally not translucent, 0–3 mm; largest lemmas generally > 2 mm wide (except in Bromus vulgaris)

16. Annual; lower glume 3(5)-veined; upper glume 5–9-veined (sect. Bromus)

17. Lemma inflated, 6–8 mm wide; awn 0–1 mm; spikelet ovate ..... B. briziformis

17' Lemma not inflated, 1–5 mm wide; awn 2–20 mm; spikelet lanceolate to lance-ovate

18. Lemma papery, veins generally strongly raised; inflorescence generally ± dense

19. Awn from > 3 mm below lemma tip, bent; all pedicels << spikelets; inflorescence branches erect ..... B. caroli-henrici

19' Awn from < 1.5 mm below lemma tip, straight (curved); generally some pedicels > spikelets; inflorescence branches erect to spreading ..... B. hordeaceus

18' Lemma leathery, veins generally not strongly raised; inflorescence generally ± open

20. Lemma awn from 1.5–5 mm below tip

21. Lower glume 7–10 mm; upper glume 8–12 mm; inflorescence branches conspicuously S-curved ..... B. arenarius

21' Lower glume 4–7 mm; upper glume 5–9.5 mm; inflorescence branches ± wavy, sometimes S-curved

22. Inflorescence panicle-like, branches generally with > 1 spikelet; membranous lemma margin 0.3–0.6 mm wide ..... B. japonicus

22' Inflorescence generally raceme-like, branches generally with 1 spikelet; membranous lemma margin 0.6–0.9 mm wide ..... B. squarrosus

20' Lemma awn from < 1.5 mm below tip

23. Anthers 2.5–5 mm; spikelets lance-linear, narrowing only slightly towards tip; lower leaf sheaths with dense, softly appressed hairs; spikelets generally purple-tinged ..... [B. arvensis]

23' Anthers < 2.5(3) mm; spikelets lance-ovate, narrowing conspicuously towards tip; lower leaf sheaths glabrous or sparsely to densely stiff-hairy; spikelets not purple-tinged.

24. Lower leaf sheath glabrous or sparsely short-hairy; spikelet widening in fruit, stalk becoming tough, persistent, visible as lemma wraps around fruit; fruit U- and V-shaped in ×-section ..... B. secalinus

24' Lower leaf sheath long-hairy; spikelets not widening substantially in fruit, lemmas generally continuing to obscure stalks; fruit flat or C-shaped in ×-section

25. Inflorescence broad, spreading, some inflorescence branches > 4 cm, 1–3 spikelets per branch; lowest lemma awn generally < other awns; spikelets 15–30 mm; 2nd lowest lemma 7.5–11 mm, glabrous or hairy, margin often broadly angled; anthers 1.3–2.5 mm ..... B. commutatus

25' Inflorescence narrow, generally unbranched, inflorescence branches < 4 cm, 1 spikelet per branch; all awns ± equal; spikelet 11–18 mm; 2nd lowest lemma 7–9 mm, glabrous, margin often smoothly curved; anthers 1.5–3 mm ..... B. racemosus

16' Perennial herb, bases fibrous, rhizomes generally 0; lower glume 1(3)-veined; upper glume 3(5)-veined (sect. Bromopsis)

26. Plants from rhizomes; awn 0–3 mm ..... B. inermis

26' Rhizomes 0; awn 1.5–11 mm

27. Lower glume generally 3-veined

28. Upper glume 5-veined

29. Ligule (1.5)2–4 mm; glume glabrous; upper glume 7–11 mm; leaf blade, sheath glabrous ..... B. laevipes

29' Ligule 0.4–1(2) mm; glume scabrous or hairy; upper glume 6–9 mm; leaf blade, sheath hairy or glabrous ..... B. pseudolaevipes

28' Upper glume 3-veined

30. Lemma awn 1.5–3(4) mm; blade 2–5 mm wide; anthers 1.5–3.5(4) mm ..... B. porteri

30' Lemma awn 3–9 mm; blade 3–12 mm wide; anthers 3–7 mm

31. Leaf blade, basal sheath hairy; stem nodes 3–7; inflorescence branches generally spreading > 90° ..... B. grandis (2)

31' Leaf blade, basal sheath glabrous; stem nodes 2–3(4); inflorescence branches generally ascending to spreading <= 90° ..... B. orcuttianus (3)

27' Lower glume generally 1-veined

32. Glumes glabrous or minutely scabrous

33. Inflorescence narrow in flower, <= 2 cm wide; branches erect or tightly ascending ..... B. suksdorfii (2)

33' Inflorescence broader in flower, > 2 cm wide; branches erect, ascending, or nodding, generally ± widely spreading

34. Ligule (2)3–6(7) mm; lemma awn (4)6–11 mm ..... B. vulgaris (2)

34' Ligule 0.5–3 mm; lemma awn (2)3–7(9) mm

35. Lemma margin not densely hairy; lemma awn (4)5–7(9) mm; inflorescence branches generally ascending to spreading <= 90° ..... B. orcuttianus (3)

35' Lemma margin densely hairy; lemma awn (2)3–5(6.5) mm; inflorescence branches spreading to nodding > 90°

36. Lemma back glabrous or sparsely hairy with hairs to 0.1 mm; anthers(0.9)1–1.4(1.6) mm; upper glumes (6.2)7.1–8.5(9.5) mm; basal sheath glabrous or long-hairy; upper stem blade hairy on upper surface; upper stem sheath, nodes generally hairy; fruit (5.4)6.2–7.2(7.5) mm ..... B. ciliatus

36' Lemma back sparsely to densely hairy with hairs > 0.1 mm; anthers (1.2)1.6–2.7(3.4) mm; upper glumes (7.8)8.9–11.3(13.2) mm; basal sheath densely, ± short-hairy, upper stem sheath glabrous; upper stem blade upper surface glabrous; upper stem nodes generally glabrous; fruit (6.9)7.7–9.7(10.5) mm ..... B. richardsonii

32' Glumes hairy

37. Inflorescence narrow at flower, <= 2 cm wide, branches erect or tightly ascending; leaf blade, sheath glabrous ..... B. suksdorfii (2)

37' Inflorescence broader at flower, > 2 cm wide, branches erect, ascending, or nodding; leaf blade, sheath hairy or glabrous

38. Ligule (2)3–6(7) mm; lemma awn (4)6–11 mm; inflorescence branches glabrous or scabrous ..... B. vulgaris (2)

38' Ligule 1–3 mm; lemma awn 3–7(9) mm; inflorescence branches hairy

39. Lower sheath long-soft-hairy, hairs 2–4 mm, or glabrous; leaf blade glabrous ..... B. orcuttianus (3)

39' Lower sheath densely short-stiff-hairy, hairs <=1 mm; leaf blade hairy

40. Longest leaf blade (13)18–38 cm; nodes 3–7 per stem ..... B. grandis (2)

40' Longest leaf blade 7.5–16.5 cm; nodes 1–2(3) per stem ..... B. hallii

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