Pedro Lake has constructed a multientry key for this treatment. An interactive version of the dichotomous key presented below can be found here.

1. Lemmas strongly keeled, at least distally; spikelets strongly laterally compressed; lower glumes 3–7(9)-veined...................................................................................................................... sect. Ceratochloa

1. Lemmas rounded over the midvein; spikelets terete to moderately laterally compressed; lower glumes 1–5-veined.

2. Awns, if present, arising less than 1.5 mm below the lemma apices; lemma apices entire, emarginate, or with teeth less than 1 mm long.

3. Lower glumes 1–3-veined; upper glumes 3–5-veined; plants perennial or annual, if annual, the lower glumes 1-veined and the upper glumes 3-veined...................................................... sect. Bromopsis

3. Lower glumes 3–5-veined; upper glumes 5–9-veined; plants annual or biennial, if biennial, the upper glumes 7-veined and/or the lateral veins of the lemmas prominently ribbed....... sect. Bromus  (in part)

2. Awns arising 1.5 mm or more below the lemma apices, lemma apices entire, emarginate, or with teeth to 5 mm long.

4. Awns usually geniculate, sometimes only divaricate, lemma teeth 2–3 mm long, usually aristate, sometimes only acuminate.................................................................................. sect. Neobromus

4. Awns straight, arcuate, or divaricate, not geniculate, sometimes absent; lemma teeth absent or to 5 mm long, acuminate.

5. Lower glumes 1–3-veined; upper glumes 3–5-veined; spikelets with parallel or diverging sides in outline, often widening distally; lemma apices bifid, teeth (0.8)1–5 mm long............... sect. Genea

5. Lower glumes 3–5-veined; upper glumes 5–9-veined; spikelets with parallel or converging sides in outline; lemma apices entire to bifid, teeth less than 1 mm long, sometimes split and appearing longer.................................................................................................... sect. Bromus  (in part)

1. Lemmas unawned or with awns to 3.5 mm long; lemmas usually glabrous, sometimes pubescent distally, veins prominent for most of their length........................................................................ 1. B. catharticus

1. Lemmas awned, awns (2)4–17 mm long; lemmas pubescent or glabrous, veins obscure or prominent.

2. Lower panicle branches shorter than 20 cm, with 1–3 spikelets on the distal 1/2, sometimes confined to the tips; culms 3–7 mm thick.

3. Lower panicle branches shorter than 20 cm, spreading to drooping............................ 2. B. sitchensis

3. Lower panicle branches shorter than 10 cm, stiffly ascending.................................... 4. B. aleutensis

2. Lower panicle branches usually less than 10 cm long, with 1–5 spikelets variously distributed; culms less than 4 mm thick.

4. Upper glume about as long as the lowest lemma in each spikelet; lemmas glabrous or pubescent distally or throughout, the marginal hairs, if present, longer than those elsewhere...... 3. B. arizonicus

4. Upper glume shorter than the lowest lemma in each spikelet; lemmas glabrous or pubescent only on the margins or throughout, if throughout, the marginal hairs similar in length to those elsewhere.

5. Panicles dense; spikelets crowded, overlapping, usually longer than the pedicels and branches; culms 20–70 cm tall, sometimes geniculate at the base; blades glabrous, smooth or scabrous; ligules 1–6 mm long........................................................................................ 5. B. maritimus

5. Panicles loose to compact; spikelets not crowded or overlapping, shorter than at least some pedicels and branches; culms 30–120(180) cm tall, erect or decumbent; blades glabrous or hairy; ligules 1–4 mm long.

6. Lemmas and sheath throats glabrous............................................................ 7. B. polyanthus

6. Lemmas and/or sheath throats with hairs.

7. Lemmas 9–13-veined, veins often raised and riblike distally or throughout... 1. B. catharticus

7. Lemmas 7–9-veined, veins usually not raised or riblike................................. 6. B. carinatus

Bromus sect. Bromopsis

1. Plants rhizomatous.

2. Culms 30–90 cm long, forming distinct clumps; rhizomes short....................................... 9. B. riparius

2. Culms 50–135 cm long, single or few together; rhizomes short to long-creeping.

3. Lemma backs sparsely to densely hairy throughout, or on the lower portion and margins, or along the marginal veins and keel; cauline nodes and leaf blades pubescent or glabrous; awns usually present, to 7.5 mm long, sometimes absent.................................................................. 10. B. pumpellianus

3. Lemma backs usually glabrous, occasionally sparsely puberulent at the base and sometimes on the margins; cauline nodes and leaf blades usually glabrous, rarely hairy; awns absent or to 3 mm long 8. B. inermis

1. Plants not rhizomatous.

4. Anthers (3.5)4–6(6.8) mm long; awns 2.5–7.5 mm long; plants of the Yukon River drainage of Alaska....................................................................................................................... 10. B. pumpellianus

4. Anthers 1–7 mm long; awns 1–12 mm long; plants of various locations in the Flora region, if in the Yukon River drainage of Alaska, anthers 1–1.4 mm long.

5. Culms with 9–20 nodes; collars and throats densely pilose; auricles 1–2.5 mm long on most lower leaves............................................................................................................... 11. B. latiglumis

5. Culms with (1)2–9 nodes; collars and throats pubescent or glabrous; auricles, if present, of various lengths.

6. Most lower glumes within a panicle 3-veined, sometimes some 1-veined.

7. Most upper glumes within a panicle 5-veined, sometimes some 3-veined.

8. Awns 1.5–3 mm long; anthers 1.5–2.5 mm long; ligules 0.5–1 mm long........... 13. B. kalmii

8. Awns 3–7 mm long; anthers 3–6 mm long; ligules to 4.2 mm long.

9. Glumes glabrous, sometimes scabrous; ligules glabrous............................ 12. B. laevipes

9. Glumes usually pubescent, rarely glabrous, sometimes scabrous; ligules usually pubescent or pilose, sometimes glabrous.

10.  Margins of the glumes and lemmas often bronze-tinged; ligules to 1.5 mm long; auricles usually present on the lower leaves, rarely absent......... 14. B. pseudolaevipes

10.  Margins of the glumes and lemmas not bronze-tinged; ligules 1–3 mm long; auricles sometimes present............................................................................ 17. B. grandis

7. Most upper glumes within a panicle 3-veined, sometimes some 5-veined.

11.  Culms 70–180 cm tall; awns 3–8 mm long; anthers 3–6 mm long.

12.  Lower leaf sheaths pilose, with hairs 2–4 mm long; blades glabrous or with pilose edges........................................................................................... 16. B. orcuttianus

12.  Lower leaf sheaths densely pubescent, with hairs to 1 mm long; blades densely pubescent.

13.  Leaf blades 7.5–16.5 cm long; culm nodes 1–2(3).............................. 15. B. hallii

13.  Leaf blades (13)18–38 cm long; culm nodes 3–7............................. 17. B. grandis

11.  Culms 30–100 cm tall; awns 1–4 mm long; anthers (1)1.5–4 mm long.

14.  Leaf blades often glaucous; glumes usually glabrous, rarely slightly pubescent.... 18. B. frondosus

14.  Leaf blades not glaucous; glumes usually pubescent, rarely glabrous.

15.  Midrib of the culm leaves abruptly narrowed just below the collar; auricles frequently present on the lower leaves; plants of western Texas..... 19. B. anomalus

15.  Midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; plants of western North America, including Texas................ 20. B. porteri

6. Most lower glumes within a panicle 1-veined, sometimes some 3-veined.

16.  Upper glumes within a panicle consistently 5-veined; collars with a dense line of hairs; lower sheaths often sericeous; ligules 0.4–1 mm long...................................... 21. B. nottowayanus

16.  All or most upper glumes within a panicle 3-veined, sometimes some with 2 additional faint lateral veins; collars glabrous or hairy, hairs evenly distributed over the surface, not in a dense line; lower sheaths glabrous or hairy, not sericeous; ligules to 6 mm long.

17.  Plants annual; lemmas glabrous, sometimes scabrous; ligules pubescent...... 22. B. texensis

17.  Plants perennial; lemmas usually pubescent on the backs and/or margins, sometimes glabrous or scabrous; ligules usually glabrous, sometimes pubescent or pilose.

18.  Awns (4)6–12 mm long; ligules 2–6 mm long.................................... 23. B. vulgaris

18.  Awns 1–8 mm long; ligules to 4 mm long.

19.  Blades densely pubescent on both surfaces, 7.5–16.5 cm long; anthers 3–6 mm long; awns 3.5–7 mm long............................................................ 15. B. hallii

19.  Blades glabrous or hairy on 1 or both surfaces, (3)5–60 cm long, if 7.5–16.5 cm long and densely pubescent on both surfaces, then anthers 1–4 mm long and/or awns 1–4 mm long.

20.  Panicle branches appressed to slightly spreading; culm nodes 1–4.

21.  Awns 2–5 mm long; anthers 2–3.5 mm long; blades flat. 26. B. suksdorfii

21.  Awns (4)5–8 mm long; anthers 3–6.5 mm long; blades sometimes involute.

22.  Culms 90–150 cm long; ligules 1–3 mm long........ 16. B. orcuttianus

22.  Culms 50–100 cm long; ligules to 1.5 mm long........... 25. B. erectus

20.  Panicle branches ascending to drooping; culm nodes (1)2–8.

23.  Midrib of the culm leaves abruptly narrowed just below the collar; auricles frequently present on the lower leaves; plants of western Texas................................................................................ 19. B. anomalus

23.  Midrib of the culm leaves not abruptly narrowed just below the collar; auricles sometimes present; plants of various distribution, including Texas.

24.  Glumes usually pubescent, rarely glabrous.

25.  Upper glume mucronate............................. 27. B. mucroglumis

25.  Upper glume not mucronate.

26.  Awns (1)2–3(3.5) mm long; blades 2–6 mm wide........ 20. B. porteri

26.  Awns 3–7(8) mm long; blades 3–19 mm wide.

27.  Anthers 3–6 mm long; ligules densely pubescent to pilose................................................... 17. B. grandis

27.  Anthers 2–4(5) mm long; ligules glabrous.

28.  Ligules 2–4 mm long..................... 24. B. pacificus

28.  Ligules 0.5–2 mm long................. 28. B. pubescens

24.  Glumes usually glabrous, sometimes pubescent.

29.  Ligules 2–3.5 mm long; auricles present............. 30. B. ramosus

29.  Ligules 0.4–2 mm long; auricles sometimes present.

30.  Lemma margins and backs usually pubescent, sometimes nearly glabrous; awns 2–4 mm long; anthers 1.8–4 mm long............................................................... 29. B. lanatipes

30.  Lemma margins conspicuously hirsute or densely pilose, at least along the lower 1/2, the backs glabrous at least on the lower lemmas in a spikelet; awns 3–5 mm long; anthers 1–2.7 mm long.

31.  Backs of all lemmas glabrous; anthers 1–1.4 mm long; upper glumes 7.1–8.5 mm long............... 31. B. ciliatus

31.  Backs of the upper lemmas in a spikelet hairy; anthers 1.6–2.7 mm long; upper glumes 8.9–11.3 mm long... 32. B. richardsonii

Bromus sect. Neobromus

This section includes one species, Bromus berteroanus.

Bromus sect. Genea

1. Lemmas 20–35 mm long.............................................................................................. 34. B. diandrus

1. Lemmas 9–20 mm long.

2. Spikelets usually shorter than the panicle branches; panicle branches ascending to spreading or drooping.

3. Lemmas 14–20 mm long; panicles with spreading, ascending, or drooping branches, rarely with any branches with more than 3 spikelets.......................................................................... 35. B. sterilis

3. Lemmas 9–12 mm long; panicles with drooping branches, often with 1 or more branches with 4–8 spikelets.............................................................................................................. 36. B. tectorum

2. Spikelets longer than the panicle branches; panicle branches ascending to spreading, never drooping.

4. Some panicle branches 1–3+ cm long, most branches visible................................. 37. B. madritensis

4. Panicle branches 0.1–1 cm long, usually not readily visible......................................... 38. B. rubens

Bromus sect. Bromus

1. Lemmas inflated, 6–8 mm wide; unawned or with awns up to 1 mm long; spikelets ovate 39. B. briziformis

1. Lemmas not inflated, 1–7 mm wide; awns 2–25 mm long, rarely lacking; spikelet shape various.

2. Lemma margins inrolled at maturity; floret bases visible at maturity; rachilla internodes visible at maturity; caryopses sometimes thick, strongly inrolled.

3. Anthers 2.5–5 mm long; awns straight; spikelets often purple-tinged; lower leaf sheaths softly appressed-hairy.................................................................................................... 40. B. arvensis

3. Anthers 0.7–2 mm long; awns straight or flexuous; spikelets not purple-tinged; lower leaf sheaths glabrous, loosely pubescent and glabrate, or evenly covered with stiff hairs.

4. Lower leaf sheaths glabrous or loosely pubescent and glabrate; lemmas 6.5–8.5(10) mm long, margins evenly rounded; awns straight or flexuous............................................. 41. B. secalinus

4. Lower leaf sheaths evenly covered with stiff hairs; lemmas 8–11.5 mm long, margins bluntly angled; awns straight.................................................................................. 42. B. commutatus

2. Lemma margins not inrolled at maturity; floret bases concealed at maturity; rachilla internodes concealed at maturity; caryopses thin, weakly inrolled or flat.

5. Lemmas 4.5–6.5 mm long, margins sharply angled; caryopses longer than the paleas... 43. B. lepidus

5. Lemmas 6.5–20 mm long, margins rounded or slightly to strongly angled; caryopses equaling or shorter than the paleas.

6. Awns arising less than 1.5 mm below the lemma apices, erect or weakly divaricate, not twisted at the base.

7. Panicle branches shorter than the spikelets; lemmas chartaceous, with prominent ribs over the veins, often concave between the veins; anthers 0.6–1.5 mm long.................. 44. B. hordeaceus

7. At least some panicle branches longer than the spikelets; lemmas coriaceous, veins obscure or distinct, not ribbed; anthers 0.7–5 mm long.

8. Lower leaf sheaths softly appressed-hairy; anthers 2.5–5 mm long; panicles 11–30 cm long............................................................................................................... 40. B. arvensis

8. Lower leaf sheaths with stiff hairs; anthers 0.7–3 mm long; panicles 4–16 cm long.

9. Anthers 0.7–1.7 mm long; rachilla internodes 1.5–2 mm long; lemmas 8–11.5 mm long, margins bluntly angled.................................................................... 42. B. commutatus

9. Anthers 1.5–3 mm long; rachilla internodes 1–1.5 mm long; lemmas 6.5–8 mm long, margins rounded............................................................................... 45. B. racemosus

6. Awns arising 1.5 mm or more below the lemma apices, erect to strongly divaricate, often twisted at the base.

10.  Panicle branches shorter than the spikelets, slightly curved or straight, panicles erect.

11.  At least the upper lemmas in each spikelet with 3 awns........................ 46. B. danthoniae

11.  All lemmas 1-awned.

12.  Lemmas 11–20 mm long; spikelets 20–50 mm long.

13.  Spikelets usually single at the nodes; glumes glabrous or puberulent; panicles strongly contracted, even at maturity.................................. 47. B. caroli-henrici

13.  Spikelets often 2 or more at each node; glumes pilose; panicles contracted when immature, more open with age.............................................. 48. B. lanceolatus

12.  Lemmas 6.5–11 mm long; spikelets 11–25 mm long.

14.  Lemmas 1.5–2 mm wide; panicles obovoid, branches sometimes verticillate 49. B. scoparius

14.  Lemmas 3–5 mm wide; panicles usually ovoid........................ 44. B. hordeaceus

10.  At least some panicle branches as long as or longer than the spikelets, sometimes sinuous; panicles nodding.

15.  Lower glumes 7–10 mm long; upper glumes 8–12 mm long; panicle branches conspicuously sinuous; awns erect to weakly spreading; lemma margins rounded.... 50. B. arenarius

15.  Lower glumes 4–7 mm long; upper glumes 5–8 mm long; panicle branches sometimes sinuous; awns erect to strongly divergent; lemma margins slightly to strongly angled above the middle.

16.  Anthers 2.5–5 mm long; spikelets often purple-tinged; culms 80–110 cm tall..... 40. B. arvensis

16.  Anthers 1–1.5 mm long; spikelets not purple-tinged; culms 20–70 cm tall.

17.  Lemmas with hyaline margins 0.3–0.6 mm wide, slightly angled above the middle; branches somewhat drooping, sometimes sinuous, often with more than 1 spikelet.................................................................................. 51. B. japonicus

17.  Lemmas with hyaline margins 0.6–0.9 mm wide, strongly angled above the middle; branches not drooping or sinuous, usually with 1 spikelet.............. 52. B. squarrosus

Bromus sect. Ceratochloa (P. Beauv.) Griseb.

Plants annual, biennial, or perennial. Spikelets elliptic to lanceolate, strongly laterally compressed, with 3–12 florets. Lower glumes 3–7(9)-veined; upper glumes 5–9(11)-veined; lemmas lanceolate, laterally compressed, strongly keeled, at least distally, apices entire or with acute teeth, teeth shorter than 1 mm; awns straight, erect to slightly divaricate.

Bromus sect. Ceratochloa is native to North and South America, and contains about 25 species. It is marked by polyploid complexes; the major one in North America is the Bromus carinatus complex. This treatment recognizes six species in the complex: B. aleutensis, B. arizonicus, B. carinatus, B. maritimus, B. polyanthus, and B. sitchensis. The lowest chromosome number known for members of this complex is 2n = 28, found in B. carinatus; the highest is 2n = 84, found in B. arizonicus. The remaining species are octoploids with 2n = 56, or hexaploids with 2n = 42. One other species in the section, B. catharticus, has been introduced from South America and is also part of a polyploid complex.

There is morphological intergradation among the species recognized here, and some evidence that these intermediates are sometimes partially fertile (Harlan 1945a, 1945b; Stebbins and Tobgy 1944; Stebbins 1947). Stebbins and Tobgy (1944) commented that partial hybrid sterility between plants placed in different species on the basis of their morphology “supports the recognition of more than one species among the octoploid members of the complex,” but later Stebbins (1981) stated that “. . . all the North American octoploids . . . should be united into a single species, in spite of the barriers of hybrid sterility that separate them.”

1. Bromus catharticus Vahl

Rescue Grass

Plants annual, biennial, or perennial; loosely cespitose or tufted. Culms 30–120 cm tall, 2–4 mm thick, erect or decumbent. Sheaths densely, often retrorsely, hairy, hairs sometimes confined to the throat; auricles absent; ligules 1–4 mm, glabrous or pilose, obtuse, lacerate to erose; blades 4–30 cm long, 3–10 mm wide, flat, glabrous or hairy on both surfaces. Panicles 9–28 cm, usually open, erect or nodding; lower branches shorter than 10 cm, 1–4 per node, spreading or ascending, with up to 5 spikelets variously distributed. Spikelets (17)20–40 mm, shorter than at least some pedicels and branches, elliptic to lanceolate, strongly laterally compressed, not crowded or overlapping, with 4–12 florets. Glumes smooth or scabrous, glabrous or pubescent; lower glumes 7–12 mm, 5–7(9)-veined; upper glumes 9–17 mm, 7–9(11)-veined, shorter than the lowest lemma; lemmas 11–20 mm, lanceolate, laterally compressed, strongly keeled, usually glabrous, sometimes pubescent distally, smooth or scabrous, 9–13-veined, veins often raised and riblike, margins sometimes conspicuous, hyaline, whitish or partly purplish, apices entire or toothed, teeth acute, shorter than 1 mm; awns absent or to 10 mm; anthers 0.5–1 mm in cleistogamous florets, 2–5 mm in chasmogamous florets. 2n = 42.

1.  Awns absent or to 3.5 mm long.................... var. catharticus

1.  Awns (5)6–10 mm long........................................... var. elatus

Bromus catharticus Vahl var. catharticus

Plants annual or biennial; tufted. Culms 30–120 cm, erect or decumbent. Sheaths densely, often retrorsely, hairy, hairs sometimes confined to the throat; ligules 1–4 mm, glabrous or pilose, erose; blades 4–26 cm long, 3–10 mm wide, glabrous or hairy on both surfaces. Panicles 9–28 cm, open, erect or nodding; lower branches 1–4 per node, spreading or ascending, with 1–5 spikelets. Spikelets 20–30 mm, with 6–12 florets. Lower glumes 5–7-veined; upper glumes 9–13 mm, (7)9(11)-veined; lemmas 11–20 mm, glabrous or scabrous, sometimes pubescent distally, (9)11–13-veined; awns absent or to 3.5 mm; anthers about 0.5 mm in cleistogamous florets, 2–4 mm in chasmogamous florets. 2n = 42.

Bromus catharticus var. catharticus is native to South America. It has been widely introduced in the Flora region as a forage crop and is now established, particularly in the southern half of the United States. It usually grows on disturbed soils.

Bromus catharticus var. elatus (E. Desv.) Planchuelo

Plants perennial; loosely cespitose. Culms 50–110 cm, erect. Sheaths usually densely retrorsely pilose, sometimes densely villous generally or only on the throat; ligules 1–3.5 mm, glabrous, obtuse, lacerate to erose; blades 10–30 cm long, 3–5 mm wide, glabrous or hairy. Panicles 10–28 cm, lax, usually open; lower branches 2–3 per node, stiffly spreading to ascending, with 2–5 spikelets. Spikelets 20–40 mm, with 4–6(8) florets. Lower glumes 5–7(9)-veined; upper glumes 10–17 mm, 7–9-veined; lemmas 11–16 mm, scabrous, glabrous or pubescent, 9–11-veined; awns (5)6–10 mm; anthers 0.6–1 mm in cleistogamous florets, 3–5 mm in chasmogamous florets. 2n = 42.

Bromus catharticus var. elatus, a native of South America, now grows in disturbed soils in central California. It has also been reported from ballast dumps in Oregon; the specimens located are actually var. catharticus.

Although published as “var. elata”, the correct Latin ending is “var. elatus”.

2. Bromus sitchensis Trin.

Sitka Brome, Alaska Brome

Plants perennial; loosely cespitose. Culms 120–180 cm tall, 3–5 mm thick, erect. Sheaths glabrous or sparsely pilose; auricles absent; ligules 3–4 mm, glabrous or hairy, obtuse, lacerate; blades 20–40 cm long, (2)5–20 mm wide, usually at least some more than 10 mm wide, flat, sparsely pilose adaxially or on both surfaces. Panicles 25–35 cm, open; lower branches to 20 cm, 2–4(6) per node, spreading, often drooping, with 1–3 spikelets on the distal 1/2, sometimes confined to the tips. Spikelets 18–38 mm, elliptic to lanceolate, strongly laterally compressed, with (5)6–9 florets. Glumes glabrous, sometimes scabrous; lower glumes 6–10 mm, 3–5-veined; upper glumes 8–11 mm, 5–7-veined; lemmas 12–14(15) mm, lanceolate, laterally compressed, 7–11-veined, strongly keeled at least distally, usually glabrous, sometimes hirtellous, margins sometimes sparsely pilose, apices entire or with acute teeth, teeth shorter than 1 mm; awns 5–10 mm; anthers to 6 mm. 2n = 42, 56.

Bromus sitchensis grows on exposed rock bluffs and cliffs, in meadows, often in the partial shade of forests along the ocean edge, and on road verges and other disturbed sites. Its range extends from the Aleutian Islands and Alaska panhandle through British Columbia to southern California.

Bromus sitchensis resembles B. aleutensis, the two sometimes being treated as conspecific varieties.

3. Bromus arizonicus (Shear) Stebbins

Arizona brome

Plants annual; tufted. Culms 30–90 cm tall, to 3 mm thick, erect. Sheaths retrorsely pilose, sometimes mostly glabrous, throats sometimes with hairs; auricles absent; ligules 1–4 mm, usually glabrous, obtuse, erose; blades 8–18 cm long, 3–9 mm wide, flat, sparsely pilose on both surfaces or the abaxial surfaces glabrous. Panicles 12–25 cm, somewhat contracted or open; lower branches shorter than 10 cm, 2–3(5) per node, initially erect to ascending, spreading at maturity, with 1–2 spikelets variously distributed. Spikelets 18–25 mm, elliptic to lanceolate, strongly laterally compressed, with 4–8 florets. Glumes subequal, smooth or scabrous; lower glumes 8–12.5 mm, 3-veined; upper glumes 9.5–14 mm, 7-veined, about as long as the lowest lemma; lemmas 9.5–14 mm, lanceolate, laterally compressed, prominently 7-veined, strongly keeled at least distally, glabrous or pubescent distally or throughout, marginal hairs, if present, longer than those elsewhere, apices entire or with acute teeth shorter than 1 mm; awns 6–13 mm, sometimes slightly geniculate; anthers 0.4–0.5 mm. 2n = 84.

Bromus arizonicus grows in dry, open areas and disturbed ground of the southwest, usually below 2000 m. Its range extends from California and southern Nevada into Arizona, New Mexico, Colorado, and northern Mexico.

Stebbins et al. (1944) demonstrated that, like Bromus carinatus, B. arizonicus obtained three of its genomes from B. catharticus or a close relative, but the remaining three genomes are not homologous with those in B. carinatus, probably being derived from a species in a section other than Ceratochloa. The small anthers of B. arizonicus strongly suggest that most seed is produced by selfing.

4. Bromus aleutensis Trin. ex Griseb.

Aleut Brome

Plants perennial; loosely cespitose. Culms 40–130 cm tall, 3–7 mm thick, often decumbent. Sheaths coarsely striate, pilose, hairs sparse to moderately dense, throats pilose; auricles rarely present; ligules 3.5–5 mm, usually glabrous, occasionally pubescent, lacerate; blades 13–35 cm long, 6–15 mm wide, flat, usually sparsely to moderately pilose on both surfaces, sometimes glabrous. Panicles 10–28 cm, erect, open or somewhat contracted; lower branches to 10 cm, 1–2 per node, stiffly ascending, with (1)2–3 spikelets on the distal 1/2, sometimes confined to the tips. Spikelets 25–40 mm, elliptic to lanceolate, strongly laterally compressed, with 3–6 florets. Glumes glabrous or pubescent; lower glumes 9–13 mm, 3–5-veined; upper glumes 10–15 mm, 7(9)-veined; lemmas 12–17 mm, lanceolate, laterally compressed, usually softly pubescent, sometimes glabrous, strongly keeled at least distally, 9(11)-veined, veins conspicuous distally, apices entire or with acute teeth shorter than 1 mm; awns (3)5–10 mm; anthers 2.2–4.2 mm. 2n = 56.

Bromus aleutensis grows in sand, gravel, and disturbed soil along the Pacific coast, from the Aleutian Islands of Alaska to western Washington, and on some lake shores of central British Columbia. It has also been found further east in Canada and in northern Idaho, always in disturbed sites, such as road edges.

Hultιn (1968) suggested that Bromus aleutensis might represent a modified version of B. sitchensis, in which reproduction occurs at a relatively early developmental state in response to the climatic conditions of the Aleutian Islands. C.L. Hitchcock (1969) reported that B. aleutensis is predominantly self-fertilizing, and B. sitchensis is predominantly outcrossing. Anther lengths close to 4.2 mm suggest that at least some plants of B. aleutensis are outcrossing.

5. Bromus maritimus (Piper) Hitchc.

Maritime Brome

Plants perennial; loosely cespitose. Culms 20–70 cm tall, to 3 mm thick, sometimes geniculate at the base. Sheaths usually smooth or scabridulous, sometimes slightly pubescent distally, not pilose at the throat; auricles absent; ligules 1–6 mm, densely hairy to ciliolate, acute to obtuse, erose; blades 6–13 cm long, 6–8 mm wide, flat, both surfaces glabrous, smooth or scabrous. Panicles 9–20 cm long, 2–2.5 cm wide, dense; lower branches shorter than 10 cm, 2–4 per node, erect, with 1–2 spikelets variously distributed. Spikelets 20–40 mm, usually longer than the branches and pedicels, elliptic to lanceolate, strongly laterally compressed, crowded, overlapping, with 3–7 florets. Glumes pubescent; lower glumes 8–12 mm, (3)5(7)-veined; upper glumes 10–13 mm, 7(9)-veined, shorter than the lowest lemma; lemmas 12–14 mm, lanceolate, laterally compressed, distinctly 9–11-veined, strongly keeled at least distally, more or less uniformly hairy, often with bronze hyaline margins, apices entire or with acute teeth shorter than 1 mm; awns (2)4–7 mm; anthers 2–4 mm. 2n = 56.

Bromus maritimus grows in coastal sands from Lane County, Oregon, to Los Angeles County, California.

6. Bromus carinatus Hook. & Arn.

Bromus carinatus is native from British Columbia to Saskatchewan and south to Mexico. It has been introduced to various more eastern locations, and to the southern Yukon Territory. The two varieties recognized here are sometimes recognized as species.

1.  Most awns 8–17 mm long................................. var. carinatus

1.  Most awns 4–7 mm long............................... var. marginatus

Bromus carinatus Hook. & Arn. var. carinatus

California Brome

Plants annual or biennial. Culms 50–100 cm tall, usually less than 3 mm thick. Sheaths mostly glabrous or retrorsely soft pilose, throats usually hairy; auricles absent; ligules 1–3(4) mm, usually glabrous, obtuse, lacerate or erose; blades 10–30 cm long, 3–6 mm wide, flat, usually sparsely pilose on both surfaces, sometimes glabrous. Panicles 15–40 cm, lax, open; lower branches usually shorter than 10 cm, 2–4 per node, ascending to strongly divergent or reflexed. Spikelets with 6–11 florets. Glumes sometimes pubescent; lower glumes 8–10 mm, 3(5)-veined; upper glumes 9.5–12 mm, 5(7)-veined; lemmas 12–16 mm, strongly keeled distally, usually more or less uniformly pubescent, sometimes scabrous, 7-veined; awns 8–17 mm, sometimes slightly geniculate; anthers 1–5 mm. 2n = 28, 56.

Bromus carinatus var. carinatus is primarily coastal and grows in shrublands, grasslands, meadows, and openings in chaparral and oak and yellow pine woodlands. It ranges from southern British Columbia through Washington, Oregon, and California to Baja California, Mexico, and extends eastward through Arizona to New Mexico.

30 Aug 2007: Changes to description based on UTC 247610, collected by John Anderson.

Bromus carinatus var. carinatus intergrades with var. marginatus, which tends to grow at higher elevations and extends further inland.

Bromus carinatus var. marginatus (Nees) Barkworth & Anderton

Mountain Brome

Plants perennial. Culms 45–120(180) cm tall, to 3 mm thick. Sheaths usually sparsely retrorsely pilose throughout, ranging from densely pilose to glabrous, except at the throat, throats always pilose; auricles sometimes present on the lower leaves; ligules 1–3.5 mm, sparsely hairy, acute to obtuse, erose or lacerate; blades 8–25 cm long, 1–12 mm wide, flat or involute, glabrous or sparsely pilose to pubescent on 1 or both surfaces. Panicles 5–20(30) cm, erect; lower branches shorter than 10 cm, 1–4 per node, erect or ascending. Spikelets with 4–9 florets. Glumes sometimes pubescent; lower glumes 7–11 mm, 3–7(9)-veined; upper glumes 9–13 mm, 5–9(11)-veined; lemmas 10–14(17) mm, coriaceous, strongly keeled at least distally, pubescent on the backs and margins, on the margins only, or glabrous, 7–9-veined; awns 4–7 mm; anthers 1–6 mm. 2n = 42.

Bromus carinatus var. marginatus is primarily an inland species and grows on open slopes, grass balds, shrublands, meadows, and open forests, in montane and subalpine zones. It grows from British Columbia to Saskatchewan, south throughout the western United States, and also extends into northern Mexico. Its elevational range is 350–2200 m in the northern part of its distribution, and 1500–3300 m in the south.

Bromus carinatus var. marginatus is variable, and intergrades with B. carinatus var. carinatus to the west, B. aleutensis to the north, and B. polyanthus to the southeast. As treated here, B. carinatus var. marginatus includes B. luzonensis J. Presl, which has been recognized mainly on the basis of its canescent sheaths and blades; this trait seems highly variable and may be environmentally determined. Although the name Bromus carinatus var. marginatus was attributed to Hitchcock by Scoggan, there is no evidence that either A.S. or C.L. Hitchcock actually made the combination.

Colorado Brome, Great Basin Brome

Plants perennial; loosely cespitose. Culms 60–120 cm tall, to 3 mm thick, erect, glabrous or puberulent. Sheaths usually smooth or scabrous, sometimes hairy except at the throat; auricles absent; ligules (1)2–2.5 mm, glabrous, obtuse, erose; blades 10–31 cm long, 2–9 mm wide, flat, sometimes scabrous, usually glabrous, rarely puberulent to pubescent near the collar. Panicles 10–20 cm, open to somewhat contracted; lower branches shorter than 10 cm, (1)2–3 per node, erect, ascending or spreading, with 1–2 spikelets variously distributed. Spikelets 20–35 mm, shorter than at least some pedicels and branches, elliptic to lanceolate, strongly laterally compressed, not crowded or overlapping, with 6–11 florets. Glumes smooth or scabrous; lower glumes (5.5)7–10(11.5) mm, 3-veined; upper glumes (7.5)9–11(12.5) mm, 5–7-veined, shorter than the lowest lemma; lemmas 12–15 mm, lanceolate, laterally compressed, strongly keeled at least distally, glabrous, sometimes scabrous, 7–9-veined, veins usually not raised or riblike, apices entire or with acute teeth, teeth shorter than 1 mm; awns 4–7 mm; anthers 1–5 mm. 2n = 56.

Bromus polyanthus grows on open slopes and in meadows. It is found primarily in the central Rocky Mountains, but the limits of its range include British Columbia in the north, California in the west, and Arizona, New Mexico, and western Texas in the south. It is sometimes treated as var. polyanthus with an erect, contracted panicle and awns 4–6 mm long; and as var. paniculatus with an open, nodding panicle and awns up to 8 mm long. Because the variation in both characters is continuous, the varieties are not recognized here.

Bromus sect. Bromopsis Dumort.

Plants usually perennial, sometimes annual. Spikelets elliptic to lanceolate, more or less terete initially, sometimes becoming laterally compressed at anthesis, with (3)4–14(16) florets. Lower glumes 1–3-veined; upper glumes 3–5-veined; lemmas elliptic to lanceolate, rounded over the midvein, apices subulate, acute, obtuse or rounded, entire or slightly emarginate; awns straight, arising less than 1.5 mm below the lemma apices.

Bromus sect. Bromopsis has sometimes been referred to as sect. Pnigma Dumort. It is native to Eurasia as well as to North and South America, and has about 90 species.

8. Bromus inermis Leyss.

Smooth Brome, Hungarian Brome, Brome Inerme

Plants perennial; rhizomatous, rhizomes short to long-creeping. Culms 50–130 cm, erect, single or a few together; nodes (2)3–5(6), usually glabrous, rarely pubescent; internodes usually glabrous, rarely pubescent. Sheaths usually glabrous, rarely pubescent or pilose; auricles sometimes present; ligules to 3 mm, glabrous, truncate, erose; blades 11–35(42) cm long, 5–15 mm wide, flat, usually glabrous, rarely pubescent or pilose. Panicles 10–20 cm, open, erect; branches ascending or spreading. Spikelets 20–40 mm, elliptic to lanceolate, terete to moderately laterally compressed, sometimes purplish, with (5)8–10 florets. Glumes glabrous; lower glumes (4)6–8(9) mm, 1(3)-veined; upper glumes (5)7–10 mm, 3-veined; lemmas 9–13 mm, elliptic to lanceolate, rounded over the midvein, usually glabrous and smooth, sometimes scabrous, margins sometimes sparsely puberulent, the basal part of the backs less frequently so, apices acute to obtuse, entire; awns absent or to 3 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3.5–6 mm. 2n = 28, 56.

Bromus inermis is native to Eurasia, and is now found in disturbed sites from Alaska and most of Canada south through most of the United States, except the southeast. It has also been used for rehabilitation, and is planted extensively for forage in pastures and rangelands from Texas to Alaska and the Yukon Territory.

Bromus inermis is similar to B. pumpellianus, differing mainly in having glabrous lemmas, nodes, and leaf blades, but a lack of pubescence is not a consistently reliable distinguishing character. Bromus inermis also resembles a recently introduced species, B. riparius, from which it differs primarily in its shorter or nonexistent awns.

9. Bromus riparius Rehmann

Meadow Bromegrass

Plants perennial; cespitose, shortly rhizomatous. Culms 30–90 cm, erect or decumbent, forming distinct clumps; nodes 2–3, glabrous or puberulent; internodes glabrous or puberulent. Sheaths glabrous or with hairs; auricles to 1 mm on the lower leaves; ligules 0.4–1.0 mm, glabrous or ciliate, truncate, erose; blades 10–20 cm long, 2–3 mm wide, scabridulous, glabrous or sparsely pilose, margins sometimes ciliate. Panicles 8–20 cm long, lax; branches scabridulous, with 1–2 spikelets. Spikelets 20–32 mm, lanceolate, becoming cuneate, with 5–8 florets. Glumes glabrous, sometimes scabridulous on the veins; lower glumes 6.5–10 mm, 1(3)-veined; upper glumes 7.5–12 mm, 3–5-veined; lemmas 10–13 mm, oblong to lanceolate, rounded over the midvein, 7–veined, glabrous or appressed-hairy, sometimes scabridulous, apices acute, entire or minutely bifid; awns 4–8 mm, straight or slightly spreading, arising less than 1.5 mm below the lemma apices; anthers 2.5–5.2 mm. 2n = 70.

Bromus riparius is an Asian species that was introduced to the United States in the late 1950s for cultivation as a pasture grass. Various cultivars are now grown, mainly in Canada and the northwestern United States. The description given here is derived in part from cultivated specimens. North American plants have sometimes been referred to incorrectly as Bromus biebersteinii Roem. & Schult. (Vogel et al. 1996). Bromus riparius differs from that species in having acute lemma apices and, usually, more pubscent leaf blades, sheaths, and lemmas.

The existence of Bromus riparius in the Flora region was not realized until shortly before this treatment was submitted for publication, making it impossible to fully investigate its similarities to B. inermis and B. pumpellianus, particularly subsp. dicksonii. It appears to differ from both species in having shorter culms on average, longer awns than B. inermis, and shorter rhizomes than B. pumpellianus subsp. pumpellianus.

10.  Bromus pumpellianus Scribn.

Arctic Brome

Plants perennial; usually rhizomatous, rhizomes short to long-creeping, sometimes cespitose. Culms 50–135 cm, erect or ascending, sometimes geniculate, usually single or a few together, sometimes clumped; nodes 2–7, pubescent or glabrous; internodes glabrous or pubescent. Sheaths pilose, villous, or glabrous; auricles sometimes present on the lower leaves; ligules to 4 mm, glabrous, truncate or obtuse, erose; blades 7–30 cm long, 2.5–8.5(9) mm wide, flat, pubescent or glabrous on both surfaces, sometimes only the adaxial surface pubescent. Panicles 10–24 cm, open or contracted, erect or nodding; branches erect to spreading. Spikelets 16–32(45) mm, elliptic to lanceolate, terete to moderately laterally compressed, sometimes purplish, with 4–14 florets. Glumes glabrous or hairy; lower glumes (4)5–10 mm, 1(3)-veined; upper glumes (5)7.5–13 mm, 3-veined; lemmas 9–16 mm, lanceolate, rounded over the midvein, sparsely to densely hairy throughout, or on the margins and lower portion of the back, or along the marginal veins and keel, apices subulate to acute, entire or slightly emarginate, lobes shorter than 1 mm; awns usually present, sometimes absent, to 7.5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3.5–7 mm. 2n = 28, 56.

The range of Bromus pumpellianus extends from Asia to North America, where it includes Alaska, the western half of Canada, the western United States as far south as New Mexico, and a few other locations eastward. It has been treated as a subspecies of B. inermis. It differs from that species primarily in its tendency to have pubescent lemmas, nodes, and leaf blades.

Two subspecies that differ in morphology and distribution are described below. Both strongly resemble the recently introduced B. riparius, differing in the case of B. pumpellianus subsp. pumpellianus in having longer rhizomes, or, in the case of B. pumpellianus subsp. dicksonii, in having a more restricted distribution. It is possible that the description and distribution of B. pumpellianus may be based in part on misidentification of B. riparius, as many taxonomists may have been unaware of the introduction of the latter species to North America.

1.  Panicles usually open; plants cespitose, sometimes shortly rhizomatous; culms ascending, often geniculate; nodes glabrous or pubescent; plants of the Yukon River drainage subsp. dicksonii

1.  Panicles contracted to open; plants rhizomatous; culms erect; nodes usually pubescent; plants of the range of the species.................................................................. subsp. pumpellianus

Bromus pumpellianus subsp. dicksonii W.W. Mitch. & Wilton

Plants cespitose, sometimes shortly rhizomatous. Culms 65–135 cm, ascending, often geniculate; nodes 3–7, glabrous or pubescent; internodes glabrous. Sheaths glabrous or hairy; auricles sometimes present; ligules 0.5–4 mm; blades 7–30 cm long, 2.5–8.5 mm wide, glabrous or hairy on both surfaces, sometimes only the adaxial surface hairy; Panicles 10–24 cm, usually open, nodding to partially erect; branches spreading to drooping. Spikelets 16–32(45) mm. Glumes glabrous or hairy; lower glumes 5–10 mm, 1(3)-veined; upper glumes 7.5–13 mm, 3-veined; lemmas 9–16 mm, sparsely to densely hairy throughout or along the marginal vein and keel; awns 2.5–7.5 mm; anthers (3.5)4–6(6.8) mm. 2n = 28.

Bromus pumpellianus subsp. dicksonii grows in shallow, rocky soils of river banks and bluffs in the Yukon River drainage of Alaska. Apart from the more restricted distribution, it is not clear how this subspecies differs from the introduced B. riparius.

Bromus pumpellianus Scribn. subsp. pumpellianus

Plants rhizomatous. Culms 50–120 cm, erect; nodes 2–3(4), usually pubescent, sometimes glabrous; internodes glabrous or pubescent. Sheaths pilose, villous, or glabrous; auricles present on the lower leaves or absent; ligules to 3 mm; blades 9–17(25) cm long, (3)4–8(9) mm wide, abaxial surfaces glabrous or pilose, adaxial surfaces usually pilose, rarely glabrous. Panicles 10–20 cm, open or contracted, erect or nodding; branches erect to spreading. Spikelets 20–30 mm. Glumes glabrous, pubescent, or hirsute; lower glumes (4)5–9 mm, 1-veined; upper glumes (5)8–11 mm, 3-veined; lemmas 9–14 mm, pubescent on the lower portion of the back and along the margins; awns usually present, to 6 mm, sometimes absent; anthers 3.5–7 mm. 2n = 56.

Bromus pumpellianus subsp. pumpellianus grows on sandy and gravelly stream banks and lake shores, sand dunes, meadows, dry grassy slopes, and road verges.

11.  Bromus latiglumis (Scribn. ex Shear) Hitchc.

Hairy Woodbrome, Flanged Brome, Brome ΰ Larges Glumes

Plants perennial; not rhizomatous. Culms 80–150 cm, erect; nodes 9–20, glabrous, usually concealed by the leaf sheaths; internodes usually glabrous, sometimes hairy just below the nodes. Sheaths overlapping, densely to moderately retrorsely pilose or glabrous over most of their surface, throats and collars densely pilose; auricles 1–2.5 mm on most lower leaves; ligules 0.8–1.4 mm, hirsute, ciliate, truncate, erose; blades 20–30 cm long, 5–15 mm wide, flat, usually glabrous, rarely pilose, with 2 prominent flanges at the collar. Panicles 10–22 cm, open, nodding; branches spreading to ascending. Spikelets 15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–9 florets. Glumes pubescent or glabrous; lower glumes 4–7.5 mm, 1(3)-veined; upper glumes 6–9 mm, 3-veined, sometimes mucronate; lemmas 8–14 mm, elliptic to lanceolate, rounded over the midvein, backs glabrous or pilose to pubescent, margins long-pilose, apices obtuse to acute, entire; awns 3–4.5(7) mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–3 mm. 2n = 14.

Bromus latiglumis grows in shaded or open woods, along stream banks, and on alluvial plains and slopes. Its range is mainly in the north-central and northeastern United States and adjacent Canadian provinces. Specimens with decumbent, weak, sprawling culms, densely hairy sheaths, and heavy panicles can be called Bromus latiglumis forma incanus (Shear) Fernald.

12.  Bromus laevipes Shear

Chinook Brome

Plants perennial; not rhizomatous. Culms 50–150 cm, erect or basally decumbent, often rooting from the lower nodes; nodes 3–5(6), pubescent; internodes usually glabrous, often puberulent-pubescent just below the nodes, rarely puberulent throughout. Sheaths glabrous, sometimes slightly pubescent near the throat, sometimes with hairs in the auricular position; auricles absent or vestigial on the basal leaves; ligules 2–4.2 mm, glabrous, obtuse, lacerate; blades 13–26 cm long, 4–10 mm wide, light green or glaucous, flat, glabrous, sometimes scabrous on both surfaces. Panicles 10–20 cm, open, nodding; branches ascending to spreading, often drooping. Spikelets 23–35 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 5–11 florets. Glumes glabrous, sometimes scabrous, margins often bronze-tinged; lower glumes 6–9 mm, 3-veined; upper glumes 8–12 mm, 5-veined; lemmas 12–16 mm, elliptic to lanceolate, rounded over the midvein, backs sparsely pilose, pubescent, or scabrous, margins densely pilose, at least on the lower 1/2, often bronze-tinged, apices acute to obtuse, entire, rarely slightly emarginate, lobes shorter than 1 mm; awns 4–6 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3.5–5 mm. 2n = 14.

The range of Bromus laevipes extends from northern Oregon to southern California. It grows in shaded woodlands and on exposed brushy slopes, at 300–1500 m.

13.  Bromus kalmii A. Gray

Kalm’s Brome, Brome de Kalm

Plants perennial; not rhizomatous. Culms 50–100(110) cm, usually erect, sometimes decumbent at the base; nodes 3–5, pubescent, puberulent, or glabrous; internodes puberulent or glabrous. Sheaths and throats pilose or glabrous; auricles absent; ligules 0.5–1 mm, glabrous, truncate, erose; blades 10–17 cm long, 5–10 mm wide, flat, with prow-shaped tips, both surfaces glabrous or pilose or only the adaxial surfaces pilose. Panicles 8–13 cm, open, drooping; branches ascending to spreading, flexuous. Spikelets 15–25 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 7–11 florets. Glumes pubescent, margins often hyaline; lower glumes 5–7.5 mm, 3-veined; upper glumes 6.5–8.5 mm, 5-veined; lemmas 7–11 mm, elliptic to lanceolate, rounded over the midvein, backs more or less uniformly pilose or pubescent, margins densely long-pilose, apices acute to obtuse, entire; awns 1.5–3 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1.5–2.5 mm. 2n = 14.

Bromus kalmii grows in sandy, gravelly, or limestone soils in open woods and calcareous fens. Its range centers in the north-central and northeastern United States and adjacent Canadian provinces.

14.  Bromus pseudolaevipes Wagnon

Woodland Brome

Plants perennial; not rhizomatous. Culms 60–120 cm, erect or spreading; nodes 4–6, pubescent or puberulent; internodes mostly glabrous, sometimes pubescent to puberulent just below the nodes. Sheaths glabrous or pilose, often pilose near the auricles; auricles usually present on the lower leaves, rarely absent; ligules to 1.5 mm, usually pubescent, sometimes glabrous, truncate to obtuse, laciniate, ciliolate; blades 10–25 cm long, 3–9 mm wide, flat, glabrous, pilose on the margins or throughout. Panicles 10–20 cm, open, usually nodding; branches ascending to spreading or reflexed. Spikelets 15–35 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–10 florets. Glumes usually pubescent, rarely glabrous, sometimes scabrous, margins often bronze-tinged; lower glumes 4–7 mm, 3-veined; upper glumes 6.5–9 mm, (3)5-veined; lemmas 10–13 mm, elliptic to lanceolate, rounded over the midvein, backs usually pubescent, sometimes glabrous distally, margins often bronze-tinged, pubescent nearly throughout, apices acute to obtuse, entire, rarely slightly emarginate, lobes shorter than 1 mm; awns 3–5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3.5–5 mm. 2n = 14.

Bromus pseudolaevipes grows in dry, shaded or semishaded sites in the chaparral, coastal sage scrub, and woodland-savannah zones, from near sea level to about 900 m, in central and southern California.

15.  Bromus hallii (Hitchc.) Saarela & P.M. Peterson

Hall’s Brome

Plants perennial; not rhizomatous. Culms 90–150 cm, erect; nodes 1–2(3), pubescent or puberulent; internodes usually puberulent, occasionally glabrous, pilose to densely pubescent below the nodes. Sheaths densely pubescent to pilose, with hairs to 1 mm, collars pilose, with hairs to 2 mm; auricles absent; ligules 0.5–2.5 mm long, sparsely to densely pubescent, obtuse, erose; blades 7.5–16.5 cm long, 3–12 mm wide, flat, densely pubescent on both surfaces. Panicles 5–16 cm, open; branches erect, ascending and appressed to slightly spreading. Spikelets 25–35(45) mm, terete to moderately laterally compressed, with 3–7 florets. Glumes sparsely to densely pubescent; lower glumes 5–8(9) mm, 1(3)-veined; upper glumes (7)8–9 mm, 3-veined, sometimes mucronate; lemmas 10–14 mm, elliptic, rounded over the midvein, backs sparsely to densely pubescent, margins pubescent, apices entire; awns 3.5–7 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3–6 mm. 2n = unknown.

Bromus hallii grows in southern California on dry, open or shaded hillsides, rocky slopes, and in montane pine woods, from 1500–2700 m.

16.  Bromus orcuttianus Vasey

Orcutt’s Brome

Plants perennial; not rhizomatous. Culms 90–150 cm, erect; nodes 2–4, pubescent or puberulent; internodes glabrous to pubescent, pilose to densely pubescent below the nodes. Basal sheaths sparingly to densely pilose, hairs 2–4 mm, occasionally glabrous; upper sheaths hairy, hairs to 1 mm, collars pilose, with hairs to 4 mm, or glabrous; auricles absent; ligules 1–3 mm, usually glabrous, occasionally pilose, obtuse, erose; blades 7–24 cm long, 3–12 mm wide, flat, usually glabrous, sometimes hairy. Panicles 7–13.5 cm, open; branches erect, ascending and appressed to slightly spreading. Spikelets 20–40 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 3–9(11) florets. Glumes usually glabrous, occasionally scabrous or pubescent; lower glumes 5–9 mm, 1(3)-veined; upper glumes 7–11 mm, 3(5)-veined, sometimes mucronate; lemmas 9–16 mm, elliptic, rounded over the midvein, backs usually pubescent, sometimes glabrous or scabrous, margins pubescent or scabrous, apices obtuse, entire; awns (4)5.5–8 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3–5 mm. 2n = 14.

Bromus orcuttianus grows on dry hillsides and rocky slopes, and in open pine woods and meadows in the mountains, from 500–3500 m. It is found in the western United States, including Washington, Oregon, California, Nevada, and Arizona.

17.  Bromus grandis (Shear) Hitchc.

Tall Brome

Plants perennial; not rhizomatous. Culms 70–180 cm, erect; nodes 3–7, pubescent or puberulent; internodes pubescent, puberulent, or glabrous. Sheaths densely pubescent, hairs to 1 mm, collars with hairs to 2 mm, midrib of the culm leaves not abruptly narrowed just below the collar; auricles sometimes present; ligules 1–3 mm, densely pubescent to pilose, obtuse, lacerate; blades (13)18–38 cm long, 3–12 mm wide, flat, sparsely to densely pubescent on both surfaces. Panicles 14–27 cm long, very open, nodding; branches flexuous, usually widely spreading, with spikelets near the tips. Spikelets 20–37(45) mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–9(10) florets. Glumes pubescent, with prominent veins, margins not bronze-tinged; lower glumes 4–8.5 mm, (1)3-veined; upper glumes 7–10 mm, 3(5)-veined, not mucronate; lemmas 9.5–14 mm, lanceolate, rounded over the midvein, backs pilose, pubescent, or glabrous, margins pilose, not bronze-tinged, apices subulate to acute, entire; awns 3–7 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3–6 mm. 2n = 14.

Bromus grandis grows on dry, wooded or open slopes, at elevations of 350–2500 m. Its range extends from central California into Baja California, Mexico.

18.  Bromus frondosus (Shear) Wooton & Standl.

Weeping Brome

Plants perennial; not rhizomatous. Culms 50–100 cm, erect to spreading; nodes 3–5, usually glabrous, rarely pubescent; internodes glabrous. Sheaths usually glabrous, sometimes pubescent or pilose, especially the lower sheaths, midrib of the culm leaves usually narrowed just below the collar; auricles absent; ligules 1–3 mm, glabrous, truncate to obtuse, laciniate; blades 10–20 cm long, 3–6 mm wide, flat, often glaucous, usually glabrous, sometimes scabrous, basal blades often pubescent. Panicles 10–20 cm, open; branches ascending and spreading or declining and drooping. Spikelets 15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (4)5–10 florets. Glumes usually glabrous, rarely slightly pubescent, 3-veined; lower glumes 5.5–8 mm; upper glumes 6.5–9 mm, often mucronate; lemmas 8–12 mm, elliptic to lanceolate, rounded over the midvein, backs pubescent or glabrous, margins usually with longer hairs, apices subulate to obtuse, entire; awns 1.5–4 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1.5–3.5 mm. 2n = 14.

Bromus frondosus grows in open woods and on rocky slopes, at 1500–2500 m. Its range extends from Colorado, Arizona, and New Mexico into Mexico.

19.  Bromus anomalus Rupr. ex E. Fourn.

Mexican Brome

Plants perennial; not rhizomatous. Culms 40–90 cm, erect; nodes (3)4–7(8), these and the internodes pubescent or glabrous. Sheaths glabrous or pilose, midrib of the culm leaves abruptly narrowed just below the collar; auricles often present on the lower leaves; ligules to 1 mm, truncate; blades 14–22(26) cm long, to 6 mm wide, flat, glabrous or pilose, not glaucous. Panicles 10–20 cm, open, nodding; branches ascending or spreading. Spikelets (14)15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–12 florets. Glumes usually pubescent, rarely glabrous; lower glumes 5–6 mm, 1–3-veined; upper glumes 6–8 mm, 3-veined, sometimes mucronate; lemmas 7–10 mm, elliptic to lanceolate, rounded over the midvein, backs and margins pubescent, apices acute to obtuse, entire; awns 1–3(5) mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–4 mm. 2n = 14.

Bromus anomalus grows on rocky slopes in western Texas and adjacent Mexico. Many records of this species in the Flora region are here treated as B. porteri, a closely related species that has sometimes been included in B. anomalus. The two differ mainly in B. anomalus having culm leaves with midribs that are narrowed just below the collar, as well as auricles.

20.  Bromus porteri (J.M. Coult.) Nash

Nodding Brome

Plants perennial; not rhizomatous. Culms 30–100 cm, erect; nodes (2)3–4(5), glabrous or pubescent; internodes mostly glabrous, puberulent near the nodes. Sheaths glabrous or pilose, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules to 2.5 mm, glabrous, truncate or obtuse, erose or lacerate; blades (3)10–25(35) cm long, 2–5(6) mm wide, flat, not glaucous, both surfaces usually glabrous, sometimes the adaxial surface pilose. Panicles 7–20 cm, open, nodding, often 1-sided; branches slender, ascending to spreading, often recurved and flexuous. Spikelets 12–38 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (3)5–11(13) florets. Glumes usually pubescent, rarely glabrous; lower glumes 5–7(9) mm, usually 3-veined, sometimes 1-veined; upper glumes 6–10 mm, 3-veined, not mucronate; lemmas 8–14 mm, elliptic, rounded over the midvein, usually pubescent or pilose, margins often with longer hairs, backs and margins rarely glabrous, apices acute or obtuse to truncate, entire; awns (1)2–3(3.5) mm, straight, arising less than 1.5 mm below the lemma apices; anthers (1)2–3 mm. 2n = 14.

Bromus porteri grows in montane meadows, grassy slopes, mesic steppes, forest edges, and open forest habitats, at 500–3500 m. It is found from British Columbia to Manitoba, and south to California and western Texas. It is closely related to B. anomalus, and has often been included in that species. It differs chiefly in its lack of auricles, and in having culm leaves with midribs that are not narrowed just below the collar.

21.  Bromus nottowayanus Fernald

Virginia Brome

Plants perennial; not rhizomatous. Culms (60)70–140 cm, erect or spreading; nodes 5–9, pubescent or glabrous, often concealed by the sheaths; internodes usually glabrous. Sheaths usually retrorsely pilose, sometimes glabrous, with a dense line of hairs at the collar, lower sheaths often sericeous; auricles absent; ligules 0.4–1 mm, often hairy, truncate, erose, ciliolate; blades 15–30 cm long, 5–12 mm wide, often shiny yellow-green, flat, abaxial surfaces pilose, adaxial surfaces glabrous or pilose over the veins. Panicles 9–25 cm, open, nodding; branches ascending or spreading, often recurved. Spikelets 18–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, often purplish, with 6–12 florets. Glumes usually pubescent; lower glumes 5.5–8 mm, 1(3)-veined; upper glumes 7–10 mm, 5-veined, often mucronate; lemmas 8–13 mm, elliptic to lanceolate, rounded over the midvein, usually uniformly densely hairy, or the backs less densely so, apices acute to obtuse, entire; awns 5–8 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2.8–3.5(5) mm. 2n = 14.

Bromus nottowayanus is native to the east-central and eastern United States, from Iowa to New York, south to Oklahoma, northern Alabama, and Virginia. It grows in damp, shaded woods, often in ravines and along streams.

22.  Bromus texensis (Shear) Hitchc.

Texas Brome

Plants annual. Culms 30–70 cm, erect or spreading; nodes 3–5, pubescent. Sheaths densely pubescent to pilose; auricles absent; ligules 2–3 mm, lanceolate, pubescent, obtuse, erose; blades 7–20 cm long, 3–7 mm wide, flat, usually pubescent to pilose, rarely glabrous. Panicles 8–15 cm, open, drooping; branches ascending to spreading. Spikelets 20–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–7 florets. Glumes glabrous or hispidulous; lower glumes 6–9 mm, 1-veined; upper glumes 8–10.5 mm, 3-veined, usually acute, rarely mucronate; lemmas 9–15 mm, lanceolate, rounded over the midvein, glabrous, sometimes scabrous, apices subulate to acute, entire; awns 4–8 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 3–5 mm. 2n = 28.

Bromus texensis grows in openings in brushy areas on rocky ground. It is rare, found only in Arizona, southern Texas, and northern Mexico.

23.  Bromus vulgaris (Hook.) Shear

Common Brome

Plants perennial; not rhizomatous. Culms 60–120 cm, erect or spreading; nodes (3)4–6(7), usually pilose; internodes glabrous. Sheaths pilose or glabrous; auricles absent; ligules 2–6 mm, glabrous, obtuse or truncate, erose or lacerate; blades 13–25(33) cm long, to 14 mm wide, flat, abaxial surfaces usually glabrous, sometimes pilose, adaxial surfaces usually pilose, sometimes glabrous. Panicles 10–15 cm, open; branches ascending to drooping. Spikelets 15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (3)4–9 florets. Glumes glabrous or pilose; lower glumes 5–8 mm, 1(3)-veined; upper glumes 8–12 mm, 3-veined; lemmas 8–15 mm, lanceolate, rounded over the midvein, backs sparsely hairy or glabrous, margins usually coarsely pubescent, sometimes glabrous, apices subulate to acute, entire; awns (4)6–12 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–4 mm. 2n = 14.

Bromus vulgaris grows in shaded or partially shaded, often damp, coniferous forests along the coast, and inland in montane pine, spruce, fir, and aspen forests, from sea level to about 2000 m. Its range extrends from coastal British Columbia eastward to southwestern Alberta and southward to central California, northern Utah, and western Wyoming.

Varieties have been described within Bromus vulgaris; because their variation is overlapping, none are recognized here.

24.  Bromus pacificus Shear

Pacific Brome

Plants perennial; not rhizomatous. Culms 60–170 cm, erect; nodes (5)6–8, pubescent; internodes usually glabrous, sometimes pubescent near the nodes. Sheaths pilose, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules 2–4 mm, glabrous, truncate, erose or lacerate; blades 20–35(37) mm long, 6–16 mm wide, flat, abaxial surfaces glabrous, adaxial surfaces pilose. Panicles 10–25 cm, open, nodding; branches ascending, spreading, or drooping. Spikelets 20–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (4)6–10 florets. Glumes pubescent; lower glumes 6–8.5 mm, 1(3)-veined; upper glumes 8–11.5 mm, 3-veined, not mucronate; lemmas 10–12 mm, lanceolate, rounded over the midvein, backs pubescent, margins more densely so, apices acute, entire; awns 3.5–7 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–4 mm. 2n = 28.

Bromus pacificus grows in moist thickets, openings, and ravines along the Pacific coast from southeastern Alaska to northern California, with a few occurrences further inland.

25.  Bromus erectus Huds.

Meadow Brome, Upright Brome, Brome Dressι

Plants perennial; not rhizomatous. Culms 50–100 cm, erect; nodes (1)2–3, usually glabrous, rarely pubescent; internodes usually glabrous, rarely pubescent. Sheaths glabrous or pilose; auricles absent; ligules to 1.5 mm, glabrous, truncate, lacerate; blades 10–20 cm long, 2–6 mm wide, often involute or folded, glabrous or sparingly hairy. Panicles 10–20 cm, erect, contracted; branches erect or ascending. Spikelets 15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 5–8(12) florets. Glumes glabrous; lower glumes 7–9 mm, 1-veined; upper glumes 9–11 mm, 3-veined; lemmas 10–13(15) mm, lanceolate, rounded over the midvein, backs and margins glabrous or sparsely pubescent, apices subulate to acute, entire; awns 5–7 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 4–6.5 mm. 2n = 56.

Bromus erectus is native to Europe. In the Flora region, it grows on disturbed soils, often over limestone. It is established in the eastern United States and Canada, and has been reported from other locations where it has not persisted.

26.  Bromus suksdorfii Vasey

Suksdorf’s Brome

Plants perennial; not rhizomatous. Culms 50–100 cm, erect; nodes 2–3(4), glabrous, internodes glabrous or puberulent just below the nodes. Sheaths glabrous; auricles absent; ligules to 1 mm, glabrous, truncate; blades (8)12–19(24) cm long, 4–8(14) mm wide, flat, glabrous, margins scabrous. Panicles 6–14 cm, erect, contracted; branches erect or ascending. Spikelets 15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (3)5–7 florets. Glumes glabrous or sparsely pubescent; lower glumes 7–11 mm, 1(3)-veined; upper glumes 9–12 mm, 3-veined; lemmas 12–15 mm, elliptic, rounded over the midvein, backs and margins pubescent or nearly glabrous, apices obtuse, entire; awns 2–5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–3.5 mm. 2n = 14.

Bromus suksdorfii grows on open slopes and in open subalpine forests, at about 1300–3300 m, from southern Washington to southern California.

27.  Bromus mucroglumis Wagnon

Sharpglume Brome

Plants perennial; not rhizomatous. Culms 50–100 cm, erect or spreading; nodes 5–7, pilose or pubescent; internodes glabrous. Basal sheaths pubescent or pilose, throats pilose; upper sheaths pubescent or glabrous, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules 1–2 mm, glabrous, truncate or obtuse; blades 20–30 cm long, (4)7–11 mm wide, flat, both surfaces pilose or the abaxial surface glabrous. Panicles 10–20 cm, open, nodding; branches ascending or spreading. Spikelets 20–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 5–10 florets. Glumes usually pilose or pubescent, rarely glabrous; lower glumes 6–8 mm, 1-veined; upper glumes 8–8.5 mm, 3-veined, mucronate; lemmas 10–12 mm, elliptic to lanceolate, rounded over the midvein, backs and margins pilose or pubescent, apices acute to obtuse, entire; awns 3–5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1.5–3 mm. 2n = 28.

Bromus mucroglumis grows at 1500–3000 m in the southwestern United States and northern Mexico.

28.  Bromus pubescens L.
[Note the authorship of this name has been corrected, based on an article by Vedlkamp {J. Torry Bot. Soc. 136-137; 2009) and confirmed by Kanchi Gandhi]..

Canada Brome

Plants perennial; not rhizomatous. Culms 65–120(150) cm, erect; nodes (3)5–7(9), usually pubescent, sometimes glabrous; internodes pubescent or glabrous. Sheaths retrorsely pilose, midrib of the culm leaves not abruptly narrowed just below the collar, collars hairy or glabrous; auricles absent; ligules 0.5–2 mm, glabrous, obtuse to truncate, erose; blades 12–32 cm long, 6–15(19) mm wide, flat, 1 or both surfaces glabrous or hairy. Panicles 10–25 cm, open, usually nodding; branches usually spreading, sometimes ascending, often drooping. Spikelets (13)15–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (4)5–10(13) florets. Glumes usually pubescent, rarely glabrous; lower glumes 4–8 mm, 1-veined; upper glumes 5–10 mm, 3(5)-veined, not mucronate; lemmas 8–12 mm, lanceolate, rounded over the midvein, backs and margins usually hairy, sometimes glabrous or scabrous, apices subulate to acute, entire; awns (3)4–7(8) mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2–4(5) mm. 2n = 14.

Bromus pubescens grows in shaded, moist, often upland deciduous woods. Its range is centered in the eastern half of the United States, and extends northward to southern Manitoba, Ontario, and Quebec, westward in scattered locations to Arizona, and southward to eastern Texas and western Florida.

29.  Bromus lanatipes (Shear) Rydb.

Wooly Brome

Plants perennial; not rhizomatous. Culms 40–90 cm, erect; nodes 3–5(7), mainly pubescent; internodes mostly glabrous, puberulent near the nodes. Basal sheaths densely pilose or glabrous; upper sheaths glabrous or almost so, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules 1–2 mm, glabrous, truncate or obtuse, sometimes lacerate; blades 5–20 cm long, to 7 mm wide, flat, both surfaces glabrous, sometimes scabrous. Panicles 10–25 cm, open, nodding; branches ascending to spreading. Spikelets 10–30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 7–12(16) florets. Glumes usually glabrous, sometimes pubescent; lower glumes 5–6.5(7) mm, 1(3)-veined; upper glumes (6)7–9 mm, 3-veined, not mucronate; lemmas 8–11 mm, elliptic, rounded over the midvein, backs and margins pubescent, sometimes nearly glabrous, apices truncate or obtuse, entire, rarely emarginate, lobes shorter than 1 mm; awns 2–4 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1.8–4 mm. 2n = 28.

Bromus lanatipes grows in a wide range of habitats, at 800–2500 m, from Wyoming through the southwestern United States to northern Mexico.

30.  Bromus ramosus Huds.

Hairy Brome

Plants perennial; not rhizomatous. Culms 40–190 cm, erect; nodes 2–4, usually pubescent; internodes usually pubescent. Sheaths with long, stiff, retrorse hairs, at least on the lower portion, midrib of the culm leaves not abruptly narrowed just below the collar; auricles present; ligules 2–3.5 mm, glabrous or sparsely pilose, rounded to truncate, erose; blades 10–60 cm long, 6–15 mm wide, flat, drooping, glabrous or sparsely hairy. Panicles 15–40 cm long, open, lax, drooping; branches spreading or drooping. Spikelets 20–40 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 3–10 florets. Glumes glabrous, scabridulous over the veins; lower glumes 5–8 mm, 1-veined; upper glumes 8–11 mm, 3-veined, mucronate; lemmas 10–14 mm, lanceolate, rounded over the midvein, margins and at least the lower 1/2 of the back pubescent, apices acute, entire or emarginate, lobes shorter than 1 mm; awns 4–7 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 2.5–4 mm. 2n = 14, 28, 42.

Bromus ramosus is native to Asia, Europe, and northern Africa. It is included here based on Pavlick’s (1995) statement that it is found sporadically in the southern and eastern United States; specimens to substantiate his statement have not been located.

31.  Bromus ciliatus L.

Fringed Brome, Brome Ciliι

Plants perennial; not rhizomatous. Culms 45–120(150) cm, erect; nodes (3)4–7(8), all pubescent or the lower nodes sometimes glabrous; internodes glabrous. Basal sheaths usually retrorsely pilose, sometimes glabrous; upper sheaths glabrous, throats glabrous or pilose, midrib of the culm leaves not abruptly narrowed just below the collar; auricles sometimes present; ligules 0.4–1.4 mm, usually glabrous, rarely pilose, truncate, erose; blades 13–25 cm long, 4–10 mm wide, flat, abaxial surfaces usually glabrous, sometimes pilose, adaxial surfaces usually pilose, sometimes glabrous. Panicles 10–20 cm, open, nodding; branches ascending, spreading, or drooping. Spikelets 15–25 mm, elliptic to lanceolate, terete to moderately laterally compressed, with 4–9 florets. Glumes glabrous; lower glumes 5.5–7.5 mm, 1(3)-veined; upper glumes 7.1–8.5 mm, 3-veined, not mucronate; lemmas 9.5–14 mm, elliptic to lanceolate, rounded over the midvein, backs glabrous, sometimes scabrous, margins conspicuously hirsute on the lower 1/2–2/3, apices obtuse to acute, entire; awns 3–5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1–1.4 mm. 2n = 14.

Bromus ciliatus grows in damp meadows, thickets, woods, and stream banks across almost all of northern North America except the high arctic, extending further south mainly in the western United States. Some taxonomists have named plants with different degrees of sheath pubescence as different forms. Because the variation is continuous, such differences are not formally recognized in this treatment.

32.  Bromus richardsonii Link

Richardson’s Brome

Plants perennial; not rhizomatous. Culms 50–110(145) cm, erect to spreading; nodes (3)4–5(6), usually glabrous, sometimes pubescent; internodes usually glabrous. Basal sheaths often retrorsely pilose; culm sheaths glabrous, often tufted-pilose near the auricle position, midrib of the culm leaves not abruptly narrowed just below the collar; auricles absent; ligules 0.4–2 mm, glabrous, rounded, erose, ciliolate; blades 10–35 cm long, 3–12 mm wide, flat, glabrous. Panicles 10–20(25) cm, open, nodding; branches ascending to spreading or drooping, filiform. Spikelets 15–25(40) mm, elliptic to lanceolate, terete to moderately laterally compressed, with (4)6–10(15) florets. Glumes usually glabrous, sometimes pubescent; lower glumes 7.5–12.5 mm, 1(3)-veined; upper glumes 8.9–11.3 mm, 3-veined, often mucronate; lemmas 9–14(16) mm, elliptic, rounded over the midvein, margins more or less densely pilose on the lower 1/2 or 3/4, lower lemmas in a spikelet glabrous across the back, uppermost lemmas with appressed hairs on the back, apices obtuse, entire; awns (2)3–5 mm, straight, arising less than 1.5 mm below the lemma apices; anthers 1.6–2.7 mm. 2n = 28.

Bromus richardsonii grows in meadows and open woods in the upper montane and subalpine zones, at about 2000–4000 m in the southern Rocky Mountains, and at lower elevations northwards. Its range extends from southern Alaska to southern California and northern Baja California, Mexico; it is found as far east as Saskatchewan, South Dakota, and western Texas. Specimens with pubsecent nodes and glumes are apparently confined to the southwestern United States.

Bromus sect. Neobromus (Shear) Hitchc.

Plants annual. Spikelets elliptic to lanceolate, more or less terete, with 3–9 florets. Lower glumes 1(3)-veined; upper glumes 3(5)-veined; lemmas lanceolate to linear-lanceolate, rounded over the midvein, apices acuminate, bifid, teeth aristate or acuminate; awns geniculate, divaricate, arising 1.5 mm or more below the lemma apices.

Bromus section Neobromus has two species native to South America, one of which has become established in the Flora region.

33.  Bromus berteroanus Colla

Chilean Chess

Plants annual; often tufted. Culms 30–60 cm, slender. Sheaths pilose-pubescent to nearly glabrous; blades 7–28 cm long, 2–9 mm wide, pilose or glabrous. Panicles 10–20 cm long, 3–9 cm wide, erect, dense; branches appressed to spreading, sometimes flexuous. Spikelets 15–20 mm, elliptic to lanceolate, more or less terete, with 3–9 florets. Glumes glabrous, acuminate; lower glumes 8–10 mm, 1-veined; upper glumes 12–16 mm, 3(5)-veined; lemmas 11–14 mm, lanceolate to linear-lanceolate, sparsely pubescent, 5-veined, rounded over the midvein, apices acuminate, bifid, teeth 2–3 mm, usually aristate, sometimes acuminate; awns 13–20 mm, geniculate, strongly to moderately twisted in the basal portion, arising 1.5 mm or more below the lemma apices; anthers 2–2.5 mm. 2n = unknown.

Bromus berteroanus is from Chile, and is now established in dry areas of western North America, including Montana, California, Nevada, Arizona, southwestern Utah, and Baja California, Mexico.

Bromus sect. Genea Dumort.

Plants annual. Spikelets with parallel or diverging sides in outline, terete to moderately laterally compressed, with 4–11 florets. Lower glumes 1–3-veined; upper glumes 3–5-veined; lemmas lanceolate to linear-lanceolate, rounded over the midvein, apices acuminate, teeth 0.8–5 mm; awns straight or arcuate, arising 1.5 mm or more below the lemma apices.

Bromus section Genea is native to Europe and northern Africa; five of its six species are established in the Flora region.

34.  Bromus diandrus Roth

Great Brome, Ripgut Grass

Plants annual. Culms 20–90 cm, erect or decumbent, puberulent below the panicle. Sheaths softly pilose, often with retrorse or spreading hairs; auricles absent; ligules 2–3 mm, glabrous, obtuse, lacerate or erose; blades 3.5–27 cm long, 1–9 mm wide, both surfaces pilose. Panicles 13–25 cm long, 2–12 cm wide, erect to spreading; branches 1–7 cm, stiffly erect to ascending or spreading, with 1 or 2 spikelets. Spikelets 25–70 mm, sides parallel or diverging distally, moderately laterally compressed, with 4–11 florets. Glumes smooth or scabrous, margins hyaline; lower glumes 15–25 mm, 1–3-veined; upper glumes 20–35 mm, 3–5-veined; lemmas 20–35 mm, linear-lanceolate, scabrous, 7-veined, rounded over the midvein, margins hyaline, apices bifid, acuminate, teeth 3–5 mm; awns 30–65 mm, straight, arising 1.5 mm or more below the lemma apices; anthers 0.5–1 mm. 2n = 42, 56.

Bromus diandrus is native to southern and western Europe. It is now established in North America, where it grows in disturbed ground, waste places, fields, sand dunes, and limestone areas. It occurs from southwestern British Columbia to Baja California, Mexico, and eastward to Montana, Colorado, Texas, and scattered locations in the eastern United States. The common name ‘ripgut grass’ suggests possible damage to animals if they consume the sharp, long-awned florets of this species.

Bromus diandrus, as treated here, includes B. rigidus Roth. Sales (1993) reduced these two taxa to varietal rank, and pointed out that the differences between them are subtle enough that identification of many specimens beyond B. diandrus sensu lato is often impossible.

35.  Bromus sterilis L.

Barren Brome

Plants annual. Culms 35–100 cm, erect or geniculate near the base, glabrous. Sheaths densely pubescent; auricles absent; ligules 2–2.5 mm, glabrous, acute, lacerate; blades 4–20 cm long, 1–6 mm wide, pubescent on both surfaces. Panicles 10–20 cm long, 5–12 cm wide, open; branches 2–10 cm, spreading, ascending or drooping, rarely with more than 3 spikelets. Spikelets 20–35 mm, usually shorter than the panicle branches, sides parallel or diverging distally, moderately laterally compressed, with 5–9 florets. Glumes smooth or scabrous, margins hyaline; lower glumes 6–14 mm, 1(3)-veined; upper glumes 10–20 mm, 3(5)-veined; lemmas 14–20 mm, narrowly lanceolate, pubescent or puberulent, 7(9)-veined, rounded over the midvein, margins hyaline, apices acuminate, bifid, teeth 1–3 mm; awns 15–30 mm, straight, arising 1.5 mm or more below the lemma apices; anthers 1–1.4 mm. 2n = 14, 28.

Bromus sterilis is native to Europe, growing from Sweden southward. It now grows in North America in road verges, fields, waste places, and overgrazed rangeland. It is widespread in western and eastern North America, but is mostly absent from the Great Plains and the southeastern states.

36.  Bromus tectorum L.

Cheatgrass, Downy Chess

Plants annual. Culms 5–90 cm, erect, slender, puberulent below the panicle. Sheaths usually densely and softly retrorsely pubescent to pilose, upper sheaths sometimes glabrous; auricles absent; ligules 2–3 mm, glabrous, obtuse, lacerate; blades to 16 cm long, 1–6 mm wide, both surfaces softly hairy. Panicles 5–20 cm long, 3–8 cm wide, open, lax, drooping distally, usually 1-sided; branches 1–4 cm, drooping, usually 1-sided and longer than the spikelets, usually at least 1 branch with 4–8 spikelets. Spikelets 10–20 mm, usually shorter than the panicle branches, sides parallel or diverging distally, moderately laterally compressed, often purplish-tinged, not densely crowded, with 4–8 florets. Glumes villous, pubescent, or glabrous, margins hyaline; lower glumes 4–9 mm, 1-veined; upper glumes 7–13 mm, 3–5-veined; lemmas 9–12 mm, lanceolate, glabrous or pubescent to pilose, 5–7-veined, rounded over the midvein, margins hyaline, often with some hairs longer than those on the back, apices acuminate, hyaline, bifid, teeth 0.8–2(3) mm; awns 10–18 mm, straight, arising 1.5 mm or more below the lemma apices; anthers 0.5–1 mm. 2n = 14.

Bromus tectorum is a European species that is well established in the Flora region and other parts of the world. It grows in disturbed sites, such as overgrazed rangelands, fields, sand dunes, road verges, and waste places. It is highly competitive and dominates rapidly after fire, especially in sagebrush areas. The resulting dense, fine fuels permanently shorten the fire-return interval, further hindering reestablishment of native species. It now dominates large areas of the sagebrush ecosystem of the western Flora region. See Schachnet et al. 2008 discuss the population genetics of this species in the midcontinental United States and cite earlier papers on a similar topic for other parts of the country.

In the southwestern United States, Bromus tectorum is considered a good source of spring feed for cattle, at least until the awns mature. Specimens with glabrous spikelets have been called Bromus tectorum forma nudus (Klett & Richt.) H. St. John. They occur throughout the range of the species, and are not known to have any other distinguishing characteristics. For this reason, they are not given formal recognition in this treatment.

37.  Bromus madritensis L.

Compact Brome

Plants annual. Culms 34–70 cm, erect or ascending, glabrous or puberulent below the panicle. Sheaths densely short-pubescent or glabrous; auricles absent; ligules 1.5–2 mm, glabrous, obtuse, erose; blades 4–20 cm long, 1–5 mm wide, flat, both surfaces pubescent or glabrous. Panicles 3–15 cm long, 2–6 cm wide, open, erect; branches (at least some) 1–3+ cm, ascending to spreading, never drooping, usually visible, with 1 or 2 spikelets. Spikelets 30–50 mm, longer than the panicle branches, not densely crowded, with parallel sides or widening distally, moderately laterally compressed, with 6–10 florets. Glumes pilose, margins hyaline; lower glumes 5–10 mm, 1-veined; upper glumes 10–15 mm, 3-veined; lemmas 12–20 mm, linear-lanceolate, often arcuate, pubescent, with longer hairs near the margins, 5–7-veined, rounded over the midvein, margins hyaline, apices acuminate, teeth 1.5–3 mm; awns 12–23 mm, straight or arcuate, arising 1.5 mm or more below the lemma apices; anthers 0.5–1 mm. 2n = 28.

Bromus madritensis is native to southern and western Europe. It is now established in North America, and grows in disturbed soil, waste places, banks, and road verges in southern Oregon, California, and Arizona.

38.  Bromus rubens L.

Foxtail Chess, Red Brome

Plants annual. Culms 10–40 cm, erect or ascending, often puberulent below the panicle. Sheaths softly pubescent to pilose; auricles absent; ligules 1–3(4) mm, pubescent, obtuse, lacerate; blades to 15 cm long, 1–5 mm wide, flat, pubescent on both surfaces. Panicles 2–10 cm long, 2–5 cm wide, erect, dense, often reddish-brown; branches 0.1–1 cm, ascending, never drooping, not readily visible, with 1 or 2 spikelets. Spikelets 18–25 mm, much longer than the panicle branches, densely crowded, subsessile, with parallel sides or widening distally, moderately laterally compressed, with 4–8 florets. Glumes pilose, margins hyaline; lower glumes 5–8 mm, 1(3)-veined; upper glumes 8–12 mm, 3–5-veined; lemmas 10–15 mm, linear-lanceolate, pubescent to pilose, 7-veined, rounded over the midvein, margins hyaline, apices acuminate, teeth 1–3 mm; awns 8–20 mm, straight, reddish, arising 1.5 mm or more below the lemma apices; anthers 0.5–1 mm. 2n =14, 28.

Bromus rubens is native to southern and southwestern Europe. It now grows in North America in disturbed ground, waste places, fields, and rocky slopes, from southern Washington to southern California, eastward to Idaho, New Mexico, and western Texas. It was found in Massachusetts before 1900 in wool waste used on a crop field; it is not established there.  The record from New York represents a rare introduction.

Bromus L. sect. Bromus

Plants usually annual, sometimes biennial. Spikelets with parallel or converging sides in outline, terete to moderately laterally compressed, with 4–30 florets. Lower glumes 3–5-veined; upper glumes 5–9-veined; lemmas elliptic, lanceolate, obovate, or rhombic, rounded over the midvein, apices subulate, acute, acuminate, or obtuse, notched, minutely bifid, or toothed, with teeth shorter than 1 mm, apices sometimes split and the teeth appearing longer; awns (0)1(3), straight or flexuous, recurved or divaricate.

Bromus sect. Bromus has about 40 species that are native to Eurasia, northern Africa, and Australia; 14 species have been introduced to the Flora region.

39.  Bromus briziformis Fisch. & C.A. Mey.

Rattlesnake Brome

Plants annual. Culms 20–62 cm, erect or ascending. Sheaths densely pilose; ligules 0.5–2 mm, hairy, obtuse, erose; blades 3–13 cm long, 2–4 mm wide, pilose to pubescent on both surfaces. Panicles 5–15 cm long, 3–7 cm wide, open, secund, nodding; branches sometimes longer than the spikelets, curved to reflexed. Spikelets 15–27 mm long, 8–12 mm wide, ovate, laterally compressed; florets 7–15, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes smooth or scabridulous; lower glumes 5–6 mm, 3–5-veined; upper glumes 6–8 mm, 7–9-veined; lemmas 9–10 mm long, 6–8 mm wide, inflated, obovate or rhombic, coriaceous, smooth or scabridulous, obscurely 9-veined, rounded over the midvein, margins hyaline, 1–1.3 mm wide, abruptly angled, not inrolled at maturity, apices acute to obtuse, bifid, teeth shorter than 1 mm; awns usually absent, sometimes to 1 mm, arising less than 1.5 mm below the lemma apices; anthers 0.7–1 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled or flat. 2n = 14.

Bromus briziformis grows in waste places, road verges, and overgrazed areas. It is native to southwest Asia and Europe, and is adventive in the Flora region, occurring from southern British Columbia as far south as New Mexico, and in scattered locations eastward. The unique shape of its spikelets has led to its use in dried flower arrangements and as a garden ornamental. The common name may refer to the similarity of the spikelets to a rattlesnake’s tail.

40.  Bromus arvensis L.

Field Brome

Plants annual. Culms 80–110 cm, erect. Lower sheaths densely, softly appressed-hairy; ligules 1–1.5 mm, hairy, obtuse, erose; blades 10–20 cm long, 2–6 mm wide, coarsely pilose on both surfaces. Panicles 11–30 cm long, 4–20 cm wide, open, erect or nodding; branches usually longer than the spikelets, ascending to widely spreading, slender, slightly curved or straight. Spikelets 10–25 mm, lanceolate, terete to moderately laterally compressed, often purple-tinged; florets 4–10, bases concealed or visible at maturity; rachilla internodes concealed or visible at maturity. Glumes glabrous; lower glumes 4–6 mm, 3-veined; upper glumes 5–8 mm, 5-veined; lemmas 7–9 mm long, 1.1–1.5 mm wide, lanceolate, obscurely 7-veined, rounded over the midvein, glabrous, coriaceous, margins slightly angled, inrolled or not at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 6–11 mm, straight, arising at varying distances below the lemma apices; anthers 2.5–5 mm. Caryopses shorter than the paleas, weakly to strongly inrolled. 2n = 14.

Bromus arvensis grows along roadsides and in fields and waste places. It is native to southern and south-central Europe.

41.  Bromus secalinus L.

Ryebrome, Brome des Seigles

Plants annual. Culms 20–80(120) cm, erect. Lower sheaths glabrous or loosely pubescent and glabrate; ligules 2–3 mm, glabrous, obtuse; blades 15–30 cm long, 2–4 mm wide, abaxial surfaces pilose or glabrous, adaxial surfaces pilose. Panicles 5–23 cm long, 2.5–12 cm wide, open, nodding; branches spreading to ascending; lower branches slightly drooping, often secund after anthesis, not sinuous. Spikelets 10–20 mm, shorter than at least some panicle branches, ovoid-lanceolate or ovate, laterally compressed, not purple-tinged; florets 4–9(10), ascending-spreading after flowering, bases visible at maturity; rachilla internodes visible at maturity. Glumes scabrous or glabrous; lower glumes 4–6 mm, 3–5-veined; upper glumes 6–7 mm, 7-veined; lemmas 6.5–8.5(10) mm long, 1.7–2.5 mm wide, elliptic, coriaceous, obscurely 7-veined, rounded over the midvein, backs usually glabrous, sometimes pubescent, scabrous to puberulent on the margins and near the apices, margins evenly rounded, inrolled at maturity, apices acute to obtuse, bifid, teeth shorter than 1 mm; awns (0)3–6(9.5) mm, straight or flexuous, arising less than 1.5 mm below the lemma apices; anthers 1–2 mm. Caryopses equaling the paleas, thick, strongly inrolled at maturity. 2n = 28.

Bromus secalinus is native to Europe. It is widespread in the Flora region, where it grows in fields, on waste ground, and along roadsides. Specimens with pubescent spikelets may be called B. secalinus var. velutinus (Schrad.) W.D.J. Koch.

42.  Bromus commutatus Schrad.

Meadow Brome, Hairy Chess

Plants annual. Culms 40–120 cm, erect or ascending. Lower sheaths densely hairy, hairs stiff, often retrorse; upper sheaths pubescent or glabrous; ligules 1–2.5 mm, glabrous or pilose, obtuse, ciliolate; blades 9–18 cm long, 2–4 mm wide, pilose on both surfaces. Panicles 7–16 cm long, 3–6 cm wide, open, erect to ascending; branches sometimes longer than the spikelets, slender, ascending to spreading. Spikelets 14–18(30) mm, oblong-lanceolate, terete to moderately laterally compressed, not purple-tinged; florets 4–9(11), bases concealed or visible at maturity; rachilla internodes 1.5–2 mm, concealed or visible at maturity. Glumes usually glabrous, sometimes scabrous or pubescent; lower glumes 5–7 mm, 5-veined; upper glumes 6–9 mm, 7(9)-veined; lemmas 8–11.5 mm long, 1.7–2.6 mm wide, elliptic to lanceolate, coriaceous, backs usually glabrous, distinctly 7(9)-veined, not ribbed, rounded over the midvein, margins scabrous or pubescent, bluntly angled, inrolled or not at maturity, apices acute to obtuse, bifid, teeth shorter than 1 mm; awns 3–10 mm, straight, arising less than 1.5 mm below the lemma apices, awn of the lowest lemma shorter than the others; anthers 0.7–1.7 mm. Caryopses equaling or shorter than the paleas, weakly to strongly inrolled. 2n = 14, 28, 56.

Bromus commutatus grows in fields, waste places, and road verges. It is native to Europe and the Baltic region; in the Flora region, it is found mainly in the United States and southern Canada. It resembles B. racemosus. Hildemar Scholz (pers. comm.) recognizes three subspecies of B. commutatus in Europe; no attempt has been made to determine which subspecies are present in the Flora region.

43.  Bromus lepidus Holmb.

Scaly Brome

Plants annual, rarely biennial. Culms 5–60 cm, erect. Sheaths pilose; ligules 0.5–1 mm, hairy, obtuse; blades 3–13 cm long, 2–4 mm wide. Panicles 2–10 cm long, 1.5–3 cm wide, erect, contracted or loose; branches shorter than the spikelets, ascending, slightly curved or straight. Spikelets 6–15 mm, lanceolate, shiny, terete to moderately laterally compressed; florets 5–12, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes glabrous; lower glumes 4–4.6 mm, 3–5-veined; upper glumes 5.2–5.4 mm, 7-veined; lemmas 4.5–6.5 mm long, 1.5–1.7 mm wide, elliptic, glabrous, distinctly 7-veined, rounded over the midvein, margins broadly hyaline, sharply angled, not inrolled at maturity, apices notched, notch at least 0.6 mm deep; awns 2–6 mm, straight, arising from the base of the apical notch but less than 1.5 mm below the lemma apices; anthers 0.5–2 mm. Caryopses longer than the paleas, thin, weakly inrolled or flat. 2n = 28.

Bromus lepidus grows in fields and waste places. It is native to Europe, and is reported from New York and Massachusetts; it probably also occurs elsewhere in the Flora region.

Specimens of Bromus hordeaceus subsp. pseudothominei often approach B. lepidus in lemma characteristics (e.g., length, smoothness, and margin angle), so that either may be misinterpreted. Characteristics helpful in distinguishing B. lepidus are the wide apical notch on the lemmas, and the length of the caryopses relative to the paleas.

44.  Bromus hordeaceus L.

Lopgrass, Brome Mou

Plants annual or biennial. Culms 2–70 cm, erect or ascending. Lower sheaths densely, often retrorsely pilose; upper sheaths pubescent or glabrous; ligules 1–1.5 mm, hairy, obtuse, erose; blades 2–19 cm long, 1–4 mm wide, abaxial surfaces glabrous or hairy, adaxial surfaces hairy. Panicles 1–13 cm long, 1–4 cm wide, erect, usually ovoid, open, becoming dense, occasionally reduced to 1 or 2 spikelets; branches shorter than the spikelets, ascending to erect, straight or almost so. Spikelets (11)14–20(23) mm, lanceolate, terete to moderately laterally compressed; florets 5–10, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes pilose or glabrous; lower glumes 5–7 mm, 3–5-veined; upper glumes 6.5–8 mm, 5–7-veined; lemmas 6.5–11 mm long, 3–5 mm wide, lanceolate, chartaceous, antrorsely pilose to pubescent, or glabrous proximally or throughout, 7–9-veined, lateral veins prominently ribbed, rounded over the midvein, hyaline margins abruptly or bluntly angled, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 6–8 mm, usually arising less than 1.5 mm below the lemma apices, straight to recurved at maturity; anthers 0.6–1.5 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled to flat. 2n = 28.

Bromus hordeaceus is native to southern Europe and northern Africa. It is weedy, growing in disturbed areas such as roadsides, fields, sandy beaches, and waste places, and can be found in many locations in the Flora region, with the exception of the central Canadian provinces and most of the southeastern United States. Its origin is obscure. Ainouche et al. (1999) reviewed various suggestions, and concluded that at least one of its diploid ancestors may have been an extinct or undiscovered species related to B. caroli-henrici, a diploid species.

The four subspecies are usually morphologically distinct. Ainouche et al. (1999), however, found no evidence of genetic differentiation among them.

1.  Lemmas (7)8–11 mm long, usually pubescent or pilose.

2.  Awns more than 0.1 mm wide at the base, straight, erect; culms (3)10–70 cm long        subsp. hordeaceus

2.  Awns less than 0.1 mm wide at the base, often divaricate or recurved at maturity; culms 15–25(60) cm long            subsp. molliformis

1.  Lemmas 6.5–8(9) mm long, glabrous or pubescent.

3.  Culms (3)10–70 cm long; panicles up to 10 cm long, usually with more than 1 spikelet; lemmas usually glabrous; caryopses usually as long as the paleas; habitat various subsp. pseudothomineii

3.  Culms 2–16 cm long; panicles 1–3 cm long, often reduced to 1 spikelet; lemmas pubescent or glabrous; caryopses shorter than the paleas; plants of maritime or lacustrine sands subsp. thominei

Bromus hordeaceus L. subsp. hordeaceus

Culms (3)10–70 cm. Panicles (3)5–10 cm, usually with more than 1 spikelet. Lemmas (7)8–11 mm, usually pilose or pubescent, margins bluntly angled; awns more than 0.1 mm wide at the base, straight, erect. Caryopses shorter than the paleas.

Bromus hordeaceus subsp. hordeaceus grows throughout the range of the species, being most prevalent in southwestern British Columbia, the western United States, and the northeastern coast.

Bromus hordeaceus subsp. molliformis (J. Lloyd ex Billot) Maire & Weiller

Culms 15–25(60) cm. Panicles to 10 cm, usually with more than 1 spikelet. Lemmas (7)8–11 mm, pubescent, margins rounded; awns less than 0.1 mm wide at the base, often divaricate or recurved at maturity. Caryopses shorter than the paleas.

Bromus hordeaceus subsp. molliformis grows in California and other scattered locations, including Idaho, New Mexico, and southern Michigan.

Bromus hordeaceus subsp. pseudothominei (P.M. Sm.) H. Scholz

Culms (3)10–70 cm. Panicles to 10 cm, usually with more than 1 spikelet. Lemmas 6.5–8(9) mm, usually glabrous, margins often abruptly angled; awns straight, erect. Caryopses usually as long as the paleas.

Bromus hordeaceus subsp. pseudothominei grows sporadically throughout the range of the species in the Flora region. Hitchcock (1951) included B. hordeaceus subsp. pseudothominei in B. racemosus.

Bromus hordeaceus subsp. thominei (Hardouin) Braun-Blanq.

Culms 2–16 cm. Panicles 1–3 cm, often reduced to 1 spikelet. Lemmas 6.5–7.5 mm, pubescent or glabrous, margins bluntly angled; awns sometimes divaricate at maturity. Caryopses shorter than the paleas.

Bromus hordeaceus subsp. thominei grows along the Pacific coast of Canada, from the Queen Charlotte Islands to Vancouver Island, as well as at inland locations in British Columbia; it has also been recorded from California, Massachusetts, and Rhode Island.

45.  Bromus racemosus L.

Smooth Brome, Brome ΰ Grappes

Plants annual. Culms 20–110 cm, erect or ascending. Lower sheaths densely hairy, hairs stiff, often retrorse; upper sheaths glabrous or pubescent; ligules 1–2 mm, glabrous or hairy, erose; blades 7–18 cm long, 1–4 mm wide, pilose on both surfaces. Panicles 4–16 cm long, 2–3 cm wide, erect, open; branches sometimes longer than the spikelets, slender, usually ascending, slightly curved or straight. Spikelets 12–20 mm, lanceolate, terete to moderately laterally compressed; florets 5–6, bases concealed at maturity; rachilla internodes 1–1.5 mm, concealed at maturity. Glumes smooth to scabrous; lower glumes 4–6 mm, (3)5-veined; upper glumes 4–7 mm, 7-veined; lemmas 6.5–8 mm long, 3–4.5 mm wide, elliptic to lanceolate, coriaceous, backs smooth, distinctly 7(9)-veined, not ribbed, rounded over the midvein, margins scabrous, rounded, not inrolled at maturity, apices acute to obtuse, bifid, teeth shorter than 1 mm; awns 5–9 mm, all more or less equal in length, straight, arising less than 1.5 mm below the lemma apices; anthers 1.5–3 mm. Caryopses shorter than the paleas, thin, weakly inrolled or flat. 2n = 28.

Bromus racemosus grows in fields, waste places, and road verges. It is native to western Europe and the Baltic region, and occurs throughout much of southern Canada and the United States. It is similar to B. commutatus. Hitchcock (1951) included B. hordeaceus subsp. pseudothominei in B. racemosus.

46.  Bromus danthoniae Trin. ex C.A. Mey.

Three-Awned Brome

Plants annual. Culms 5–40 cm, erect or ascending. Sheaths glabrous or pubescent; ligules 1.2–2.6 mm, puberulent, obtuse, laciniate; blades 2–15 cm long, 2–5 mm wide, pubescent on both surfaces. Panicles 2–12 cm long, 1–5 cm wide, dense, ovoid, stiffly erect, sometimes racemose; branches shorter than the spikelets, ascending, slightly curved or straight. Spikelets 10–40(45) mm long, 4–10 mm wide, lanceolate to elliptic or oblong, laterally compressed; florets 5–8(10), bases concealed at maturity; rachilla internodes concealed at maturity. Glumes glabrous or pubescent; lower glumes 5–8.5 mm, 3–5-veined, lanceolate; upper glumes 6.5–9.5 mm, 7–9(11)-veined, elliptic; lemmas 8–12(13.5) mm long, 6–7 mm wide, oblanceolate, veins glabrous, scabridulous, or ciliolate, glabrous or pubescent elsewhere, 9–11-veined, rounded over the midvein, margins broadly hyaline, bluntly angled above the middle, not inrolled at maturity, apices subulate to acute or obtuse, toothed, teeth shorter than 1 mm; awns usually 3 on the upper lemmas in each spikelet, arising 2–4 mm below the lemma apices, purple or deep red, central awn 5–25 mm, flattened at the base, divaricate and sometimes twisted at maturity, lateral awns 4–10 mm, erect or reflexed, sometimes absent or much reduced on the lower lemmas; anthers 1–1.8 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled or flat. 2n = 14.

Bromus danthoniae is native from the western Asia to southern Russia and Tibet. It was collected in 1904 in Ontario; no other North American collections are known.

47.  Bromus caroli-henrici Greuter

Plants annual. Culms 10–40 cm, erect or ascending. Lower sheaths densely retrorsely villous-pubescent, upper sheaths glabrous; ligules 0.5–1.0 mm, glabrous, truncate, dentate or lacerate; blades 5–20 cm long, 1.5–4 mm wide, pilose, sparingly pubescent, or subglabrous. Panicles 6–15 cm long, 1–2 cm wide, racemose, dense, strongly contracted, stiffly erect; branches shorter than the spikelets, stiff, erect, straight. Spikelets 17–45 mm long, 4–7 mm wide, narrowly oblong or lanceolate, terete to moderately laterally compressed, usually 1 per node; florets (4)8–12, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes glabrous or puberulent; lower glumes 7–9 mm, 3-veined, upper glumes 8–11 mm, 5–7-veined; lemmas 11–15(17) mm long, 3–5 mm wide, lanceolate, glabrous or pubescent, 9-veined, rounded over the midvein, margins bluntly angled, not inrolled at maturity, apices and teeth acuminate, teeth less than 1 mm; awns 12–20 mm, strongly divaricate at maturity, flattened and often basally twisted, arising 1.5 mm or more below the lemma apices; anthers 0.75–1.5 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled or flat. 2n = 14, 28.

Bromus caroli-henrici is native to Mediterranean Europe. In the Flora region, it grows in open, disturbed areas in north-central California. It has been misidentified as B. alopecuros Poir., but differs mainly in having single spikelets at the nodes versus 2–3, and in its acuminate versus broadly triangular lemma teeth.

48.  Bromus lanceolatus Roth

Lanceolate Brome

Plants annual. Culms 30–70 cm, erect or ascending. Sheaths often densely hairy, with soft, white hairs; ligules 1–2 mm, hairy, obtuse, erose; blades 10–30 cm long, 3–5 mm wide, glabrous or pubescent. Panicles 5–15 cm long, 2–9 cm wide, erect, densely contracted when immature, more open with age; branches usually shorter than the spikelets, rigid, ascending to slightly spreading, slightly curved or straight. Spikelets 20–50 mm, lanceolate, terete to moderately laterally compressed, often 2+ per node; florets 7–20, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes pilose; lower glumes 5–9 mm, 3–5-veined; upper glumes 8–12 mm, 5–7-veined; lemmas 11–20 mm long, 1.8–2.5 mm wide, lanceolate, pilose, obscurely 7-veined, rounded over the midvein, margins rounded, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 6–12 mm, to 20 mm on some distal lemmas, divaricate when mature, arising 1.5 mm or more below the lemma apices; anthers 1–1.5 mm. Caryopses equaling or slightly shorter than the paleas, thin, weakly inrolled or flat. 2n = 28, 42.

Bromus lanceolatus grows in waste places, and is also cultivated as an ornamental. It has been introduced to the Flora region from southern Europe, and is reported from scattered sites, e.g., Yonkers, New York (wool waste); College Station, Texas; and Pima County, Arizona.

49.  Bromus scoparius L.

Broom Brome

Plants annual. Culms (9)20–40 cm, erect or ascending. Sheaths sparsely pubescent or glabrous; ligules 0.8–1.5 mm, glabrous or hairy, obtuse; blades 5–20 cm long, 2–5 mm wide, abaxial surfaces glabrous, adaxial surfaces pilose. Panicles 2–7 cm long, 1–4 cm wide, erect, dense, obovoid, wedge-shaped at the base, sometimes interrupted; branches shorter than the spikelets, erect, straight or almost so, sometimes verticillate. Spikelets 12–25 mm, lanceolate, crowded, terete to moderately laterally compressed; florets 5–10, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes scabrous to pubescent; lower glumes 3–4 mm, 3–5-veined; upper glumes 5–7 mm, 5–7-veined; lemmas 7–10 mm long, 1.5–2 mm wide, lanceolate, glabrous, obscurely 7-veined, rounded over the midvein, margins rounded, not inrolled at maturity, apices sharply acute, bifid, teeth shorter than 1 mm; awns 7–10 mm, flattened at the base, divaricate or recurved when mature, arising 1.5 mm or more below the lemma apices; anthers 0.3–0.5 mm. Caryopses shorter than the paleas, thin, weakly inrolled or flat. 2n = 14.

Bromus scoparius is native to southern Europe. It grows in waste places, and in the Flora region is recorded from California and New York.

50.  Bromus arenarius Labill.

Australian Brome

Plants annual. Culms 20–40 cm, erect to ascending. Sheaths densely retrorsely pilose; ligules 1.5–2.5 mm, glabrous or pilose, obtuse, lacerate; blades 7–8 cm long, 3–6 mm wide, pilose on both surfaces. Panicles (4)10–15 cm long, 4–7 cm wide, open, nodding; branches sometimes longer than the spikelets, spreading or ascending, sinuous. Spikelets 10–20 mm, lanceolate, terete to moderately laterally compressed; florets 5–9(11), bases concealed at maturity; rachilla internodes concealed at maturity. Glumes densely pilose; lower glumes 7–10 mm, 3-veined; upper glumes 8–12 mm, (5)7-veined; lemmas 9–11(13) mm long, 1–1.8 mm wide, lanceolate, densely pilose, distinctly 7-veined, rounded over the midvein, margins rounded, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 10–16 mm, straight to weakly spreading, arising 1.5 mm or more below the lemma apices; anthers 0.7–1 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled. 2n = unknown.

Bromus arenarius grows in dry, often sandy slopes, fields, and waste places. Native to Australia, it is now widely scattered throughout California, and is also recorded from Oregon, eastern Nevada, Arizona, New Mexico, Texas, and Pennsylvania.

51.  Bromus japonicus Thunb.

Japanese Brome

Plants annual. Culms (22)30–70 cm, erect or ascending. Sheaths usually densely pilose; upper sheaths sometimes pubescent or glabrous; ligules 1–2.2 mm, pilose, obtuse, lacerate; blades 10–20 cm long, 2–4 mm wide, usually pilose on both surfaces. Panicles 10–22 cm long, 4–13 cm wide, open, nodding; branches usually longer than the spikelets, spreading to ascending, slender, flexuous, somewhat drooping, sometimes sinuous, often with more than 1 spikelet. Spikelets 20–40 mm, lanceolate, terete to moderately laterally compressed; florets 6–12, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes smooth or scabrous; lower glumes 4.5–7 mm, (3)5-veined; upper glumes 5–8 mm, 7-veined; lemmas 7–9 mm long, 1.2–2.2 mm wide, lanceolate, coriaceous, smooth proximally, scabrous on the distal 1/2, obscurely (7)9-veined, rounded over the midvein, margins hyaline, 0.3–0.6 mm wide, obtusely angled above the middle, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 8–13 mm, strongly divergent at maturity, sometimes straight, twisted, flattened at the base, arising 1.5 mm or more below the lemma apices; anthers 1–1.5 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled or flat. 2n = 14.

Bromus japonicus grows in fields, waste places, and road verges. It is native to central and southeastern Europe and Asia, and is distributed throughout much of the United States and southern Canada, with one record from the Yukon Territory.

52.  Bromus squarrosus L.

Squarrose Brome

Plants annual. Culms 20–60 cm, erect or geniculately ascending. Lower sheaths densely pilose; ligules 1–1.5 mm, hairy, obtuse, erose, ciliolate; blades 5–15 cm long, 4–6 mm wide, densely pilose on both surfaces. Panicles 7–20 cm long, 4–8 cm wide, racemose, open, nodding, often with few spikelets, usually secund; branches sometimes longer than the spikelets, ascending-spreading, flexuous, slightly curved, usually with 1 spikelet. Spikelets 15–70 mm, broadly oblong or ovate-lanceolate, terete to moderately laterally compressed; florets 8–30, bases concealed at maturity; rachilla internodes concealed at maturity. Glumes smooth, scabrous, or densely hairy, hairs to 0.8 mm; lower glumes 4.5–7 mm, 3–5(7)-veined; upper glumes 6–8 mm, 7-veined; lemmas 8–11 mm long, 2–2.4 mm wide, lanceolate, chartaceous, smooth, scabridulous, or densely hairy with hairs up to 0.8 mm long, 7–9-veined, rounded over the midvein, margins hyaline, 0.6–0.9 mm wide, strongly angled above the middle, not inrolled at maturity, apices acute, bifid, teeth shorter than 1 mm; awns 8–10 mm, flattened and sometimes twisted at the base, divaricate at maturity, arising 1.5 mm or more below the lemma apices; anthers 1–1.3 mm. Caryopses equaling the paleas, thin, weakly inrolled or flat. 2n = 14.

Bromus squarrosus grows in overgrazed pastures, fields, waste places, and road verges. Native to central Russia and southern Europe, it can be found mainly in southern Canada and the northern half of the United States. Saarela (2008) reported the presence of the two varieties described below in in his treatment of Bromus for British Columbia. The description in FNA 24 applied only to var. squarrosa. The description given here has been amended to include both varieties.

1. Glumes and lemmas glabrous or scabrous ..... var. squarrosus
1. Glumes and lemmas densely pubescent, hairs to 0.8 mm long .... var. villosus

Bromus squarrosus L. var. squarrosus

Found throughout the range shown on the map.

Bromus squarrosus var. villosus Roth

At present, known in North America only from specimens cited by Saarela (2008), all of which came from southern British Columbia. Examination of specimens of Bromus squarrosus from other areas may show it to be more widespread in North America.