1. Awns 4-6 cm long *B. diandrus (NSW VIC TAS NT SA WA QLD)
B. gussonii, B. rigidus
Awns up to 3 cm long or absent 2

2. Awn arising from back of lemma 3/4 way from base *B. alopecuros (NSW VIC TAS SA WA QLD)
B. alopecuroides, B. lanceolatus
Awn arising at or near lemma apex 3

3. Lemmas laterally compressed and sharply keeled 4
Lemmas not compressed, rounded on back 7

4. Inflorescence ±compact with rigid branches *B. brevis (NSW TAS)
Inflorescence ±loose with flexuous branches 5

5. Glumes spreading, awned *B. cebadilla (NSW VIC TAS)
B. stamineus
Glumes nor spreading or awned 6

6. Lemma awns less than 3 mm long or lemmas awnless; spikelets glabrous *B. catharticus (NSW VIC TAS SA WA QLD)
B. unioloides, B. wildenowii
Lemma awns 5-7mm long; spikelets pubescent *B. lithobius (NSW VIC TAS)
B. fonkii, B. cebadilla auct.

7. Lower glume 3-7-nerved; upper glume 5-9-nerved 8
Lower glume usually 1-nerved; upper glume 1-3-nerved 11

8. Lower leaf-sheaths glabrous or weakly hairy *B. secalinus (NSW)
Lower leaf-sheaths distinctly hairy 9

9. Most pedicels longer than their spikelets; inflorescence ±lax *B. racemosus (NSW VIC)
Most pedicels shorter than their spikelets; inflorescence ±dense 10

10. Awns flattened at base *B. hordeaceus subsp. molliformis (NSW QLD)
B. molliformis
Awns terete at base *B. hordeaceus subsp. hordeaceus (NSW VIC TAS SA WA QLD)
B. mollis

11. Lemmas awnless or with short awns to 3 mm long *B. inermis (NSW)
Lemmas awned with awns more than 4 mm long 12

12. Inflorescence open and loose 13
Inflorescence contracted 14

13. Awns straight *B. sterilis (NSW VIC TAS WA)
Awns curving away from spikelet B. arenarius (NSW VIC TAS SA WA QLD)
B. japonicus

14. Inflorescence very dense; lemma teeth 2-4 mm long *B. rubens (NSW VIC SA WA QLD)
Inflorescence moderately dense; lemma teeth
1-2 mm long

15. Spikelets 2.5-3.5 cm long (including awns) *B. tectorum (NSW VIC)
B. tectorum var. hirsutus
Spikelets 3.5-6 cm long *B. madritensis (NSW VIC TAS SA WA QLD)

Key to Bromus derived from Wheeler, Jacobs and Norton 1990

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith