| 1. | Rachis fragile; lateral spikelets sterile | 2 |
| Rachis tough; lateral spikelets male or perfect | 3 | |
| 2. | Spikes with 2 rows of fertile spikelets | *H. distichon (NSW VIC TAS SA WA QLD) |
| Spikes with 6 rows of fertile spikelets | *H. vulgare (NSW VIC TAS SA WA QLD) | |
| 3. | Densely tufted perennial | *H. secalinum (NSW VIC TAS SA WA QLD) Critesion secalinum |
| Annual | 4 | |
| 4. | Leaves without auricles | 5 |
| Leaves with prominent auricles | 6 | |
| 5. | Lateral spikelets with both glumes bristle-like | *H. hystrix (NSW VIC TAS SA WA QLD) Hordeum geniculatum, Critesion hystrix |
| Lateral spikelets with one glume bristle-like and the other broadly winged at base | *H. marinum (NSW VIC TAS SA QLD) Critesion marinum, Hordeum maritimum |
|
| 6. | Lateral spikelet lemmas shorter than or longer than central spikelet lemma; awns of lateral lemmas shorter than awn of central lemma | *H. murinum (TAS) |
| Lateral spikelet lemmas longer than central spikelet lemma; awns of lateral lemmas longer than central spikelet lemma | 7 | |
| 7. | Anthers of central spikelet 0.2-0.5 mm long | *H. glaucum (NSW VIC TAS NT SA WA QLD) Hordeum glaucum, H. murinum subsp. glaucum |
| Anthers of central spikelet 0.7-1.4 mm long | *H. leporinum (NSW VIC TAS NT SA WA QLD) Critesion murinum subsp. leporinum, H. murinum subsp. leporinum |
Key to Hordeum derived from Love 1984
Taxonomic name: