1	"1st glume 1-veined; 2nd glume 3-veined; if the glumes have more veins then the lemma awns are over 20 mm long"	2
1	"1st glume 3–5-veined; 2nd glume 5–9-veined"	4
2	"1st glume 13–20 mm long"	"Bromus diandrus"
2	"1st glume 5–10 mm long"	3
3	"Stems glabrous or scabrid below the panicle; at least some pedicels at least 10 mm long"	"Bromus madritensis"
3	"Stems pubescent below the panicle; pedicels 0–10 mm long"	"Bromus rubens"
4	"Lemma strongly compressed, keeled"	5
4	"Lemma rounded on the back, not keeled"	6
5	"Perennial; lemmas minutely scabrid or glabrous except for scabrid keels"	"Bromus catharticus"
5	"Annual; lemmas hairy"	"Bromus lithobius"
6	"Lemma awn flat, twisted and spreading horizontally"	"Bromus alopecuros"
6	"Lemma awn not flattened or twisted, erect"	7
7	"Panicle dense, the longest pedicels usually less than 6 mm long"	"Bromus hordeaceus"
7	"Panicle very lax, the longest pedicels usually at least 10 mm long"	"Bromus arenarius"