| 1. | Annual; lower glume 0.5 mm long | G. drummondii (WA) |
| Perennial; lower glume more than 1.5 mm long | 2 | |
| 2. | Lower glume 3-5-nerved, 7-8 mm long | G. latispicea (NSW) |
| Lower glume 1-nerved, 1.5-5.5 mm long | 3 | |
| 3. | Lemmas more than 5.5 mm long | 4 |
| Lemmas 3-5 mm long | 5 | |
| 4. | Lower glume 2-3 mm long | *G. fluitans (TAS) |
| Lower glume 5-7 mm long | G. australis (NSW VIC TAS SA WA) | |
| 5. | Spikelets 5-12 mm long | *G. maxima (NSW VIC TAS WA QLD) G. aquatica |
| Spikelets 13-25 mm long | 6 | |
| 6. | Lemma toothed at apex; paleas slightly longer than lemma | G. declinata (NSW VIC TAS SA WA) |
| Lemma ±entire at apex; paleas shorter than lemma | *G. plicata (VIC TAS) |
Key to Glyceria derived from Wheeler, Jacobs and Norton 1990
Taxonomic name: