1	Lemmas strongly laterally compressed and keeled (Bromus Sect. Ceratochloa)		Bromus catharticus
+	Lemmas rounded on the back		(2)
2 (1)	Lemmas, or at least the upper, 3-awned, widened above the middle into a very distinct, obtuse angle (Bromus Sect. Triniusa)		Bromus danthoniae
+	Lemmas 1-awned or rarely awnless, if 3-awned then lemmas not or scarcely widened above the middle into an obtuse angle		(3)
3 (2)	Spikelets ovate, lanceolate, elliptic or oblong, tapering towards the tip, opening at anthesis, usually closing at maturity; lower glume 3-7-nerved; upper glume 5-9-nerved (Bromus Sect. Bromus)		(4)
+	Spikelets oblong or wedge-shaped, not elliptic nor lanceolate and not tapering towards the tip, gaping at maturity; lower glume 1-nerved (3-nerved in B. sericeus); upper glume 3-nerved (5-nerved in B. sericeus)		(9)
4 (3)	Panicle dense, erect, sometimes interrupted or verticillate; panicle branches and pedicels much shorter than the spikelets		(5)
+	Panicle lax, erect or nodding, somewhat contracted only when young or depauperate; at least some panicle branches and pedicels as long as or longer than the spikelets		(6)
5 (4)	Lemma 3-5 mm wide; caryopsis oblanceolate, more than 1 mm wide; panicle ovoid to ovoid oblong, sometimes with few spikelets		Bromus hordeaceus
+	Lemma not more than 2 mm wide; caryopsis narrowly elliptical, c.l mm wide; panicle ovoid cuneate or verticillate		Bromus scoparius
6 (4)	Panicle lax, erect; pedicels mostly equalling or shorter than their spikelets; spikelets (excluding the awns) 20-40 mm long; lemmas 11-15 mm long		Bromus lanceolatus
+	Panicle lax, nodding; pedicels mostly longer than their spikelets		(7)
7 (6)	Lower glume 9-11 mm long; lemmas (11-) 12-18 mm long; spikelets (excluding the awns) 30-50 mm long		Bromus oxyodon
+	Lower glume up to about 9 mm long; spikelets (excluding the awns) up to 30 mm long		(8)
8 (7)	Lemmas coriaceous, markedly rhomboid with inconspicuous nerves and blunt teeth; margins of lemmas overlapping at maturity; awn usually strongly reflexed		Bromus japonicus
+	Lemmas papery, evenly curved along the margins with conspicuous nerves and usually acuminate teeth; margins of lemmas somewhat inrolled at maturity and lemmas slightly divaricate; awn usually straight and erect, rarely curved		Bromus pectinatus
9 (3)	Tufted or rhizmatous perennials (Bromus Sect. Pnigma)		(10)
+	Annuals		(15)
10 (9)	Awn stout, at least as long as the lemma, straight or recurved at maturity		Bromus porphyranthos
+	Awn fine, usually shorter than the lemma, straight at maturity, sometimes absent		(11)
11 (10)	Rhizomes short or wanting, plants laxly to densely tufted		Bromus ramosus
+	Rhizomes long and creeping, plants with few or solitary culms, rarely the culms somewhat tufted but then the inflorescence a raceme		(12)
12 (11)	Lemmas densely hairy all over the back and on the side nerves		Bromus confinis
+	Lemmas glabrous or scabrid with minute appressed bristles, rarely somewhat appressed hairy on the lower part		(13)
13 (12)	Spikelets awnless or with awn-points up to 1.5 mm long; lemmas glabrous or rarely somewhat hairy at the base; plant mostly glabrous		Bromus inermis
+	Spikelets with awns 2-5 mm long; lemmas very slightly roughened with minute appressed bristles		(14)
14 (13)	Velutinous greyish-green plants, densely hairy on leaves, sheaths and stems		Bromus tomentosus
+	Culms glabrous; leaves and sheaths green, hispid or sparsely long-hairy		Bromus stenostachyus
15 (9)	Awn 1-2 times the length of the lemma; lemma elliptic or lanceolate in side view (Bromus Sect. Genea)		(16)
+	Awn 4-6 times the length of the lemma; lemma oblanceolate in side view (Bromus Sect. Nevskiella)		Bromus gracillimus
16 (15)	Lower glume 3(-rarely 1)-nerved; upper glume 5-nerved; lowest lemma 18-25 mm long with an awn 15-45 mm long		Bromus sericeus
+	Lower glume 1-nerved; upper glume 3-nerved; lowest lemma 10-14 mm long with an awn 10-15 mm long		Bromus tectorum