Bromus 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, teeth shorter than 1 mm, apices sometimes split and the teeth appearing longer; awns (0)1(3), straight or flexuous, recurved or divaricate.

Discussion

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.

Selected References

None.

Lower Taxa

Bromus arenarius, Bromus arvensis, Bromus briziformis, Bromus caroli-henrici, Bromus commutatus, Bromus danthoniae, Bromus hordeaceus, Bromus japonicus, Bromus lanceolatus, Bromus lepidus, Bromus racemosus, Bromus scoparius, Bromus secalinus, Bromus squarrosus

Key

1	Lemmas inflated, 6-8 mm wide; unawned or with awns up to 1 mm long; spikelets ovate	Bromus briziformis
1	Lemmas not inflated, 1-7 mm wide; awns 2-25 mm long, rarely absent; spikelet shape various.	> 2
2	Lemma margins inrolled at maturity; floret bases visible at maturity; rachilla internodes visible at maturity; caryopses sometimes thick, strongly inrolled.	> 3
2	Lemma margins not inrolled at maturity; floret bases concealed at maturity; rachilla internodes concealed at maturity; caryopses thin, weakly inrolled or flat.	> 5
3	Anthers 2.5-5 mm long; awns straight; spikelets often purple-tinged; lower leaf sheaths with soft, appressed hairs	Bromus 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
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	Bromus secalinus
4	Lower leaf sheaths evenly covered with stiff hairs; lemmas 8-11.5 mm long, margins bluntly angled; awns straight	Bromus commutatus
5	Lemmas 4.5-6.5 mm long, margins sharply angled; caryopses longer than the paleas	Bromus lepidus
5	Lemmas 6.5-20 mm long, margins rounded or slightly to strongly angled; caryopses equaling or shorter than the paleas.	> 6
6	Awns arising less than 1.5 mm below the lemma apices, erect or weakly divaricate, not twisted at the base.	> 7
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	Bromus 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
8	Lower leaf sheaths with soft, appressed hairs; anthers 2.5-5 mm long; panicles 11-30 cm long	Bromus arvensis
8	Lower leaf sheaths with stiff hairs; anthers 0.7-3 mm long; panicles 4-16 cm long.	> 9
9	Anthers 0.7-1.7 mm long; rachilla internodes 1.5-2 mm long; lemmas 8-11.5 mm long, margins bluntly angled	Bromus commutatus
9	Anthers 1.5-3 mm long; rachilla internodes 1-1.5 mm long; lemmas 6.5-8 mm long, margins rounded	Bromus racemosus
6	Awns arising 1.5 mm or more below the lemma apices, erect to strongly divaricate, often twisted at the base.	> 10
10	Panicle branches shorter than the spikelets, slightly curved or straight, panicles erect.	> 11
11	At least the upper lemmas in each spikelet with 3 awns	Bromus danthoniae
11	All lemmas 1-awned.	> 12
12	Lemmas 11-20 mm long; spikelets 20-50 mm long.	> 13
13	Spikelets usually single at the nodes; glumes glabrous or puberulent; panicles strongly contracted, even at maturity	Bromus caroli-henrici
13	Spikelets often 2 or more at each node; glumes pilose; panicles contracted when immature, more open with age	Bromus lanceolatus
12	Lemmas 6.5-11 mm long; spikelets 11-25 mm long.	> 14
14	Lemmas 1.5-2 mm wide; panicles obovoid, branches sometimes verticillate	Bromus scoparius
14	Lemmas 3-5 mm wide; panicles usually ovoid	Bromus hordeaceus
10	At least some panicle branches as long as or longer than the spikelets, sometimes sinuous; panicles nodding.	> 15
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	Bromus 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
16	Anthers 2.5-5 mm long; spikelets often purple-tinged; culms 80-110 cm tall	Bromus arvensis
16	Anthers 1-1.5 mm long; spikelets not purple-tinged; culms 20-70 cm tall.	> 17
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	Bromus 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	Bromus squarrosus