| 1. | Fertile spikelet subtended by 6-7 sterile spikelets | *P. paradoxa (NSW VIC TAS SA WA QLD) |
| Fertile spikelet not subtended by sterile spikelets | 2 | |
| 2. | Glumes wingless on keel or with narrow wings | 3 |
| Glumes prominently winged on keel | 4 | |
| 3. | Leaves uniformly green | *P. arundinacea var. arundinacea (NSW VIC TAS WA) |
| Leaves longitudinally striped with white stripes | *P. arundinacea var. picta (NSW SA WA) | |
| 4. | Sterile lemmas subequal | 5 |
| Sterile lemmas unequal; lower very small or both absent |
6 | |
| 5. | Sterile lemmas more than 2 mm long | *P. canariensis (NSW VIC TAS SA WA QLD) |
| Sterile lemmas 1 mm long or less | *P. angusta (NSW WA QLD) | |
| 6. | Sterile lemmas absent or reduced to two tiny scales; fertile floret glabrous | *P. coerulescens (NSW VIC WA) |
| Sterile lemmas unequal or lower reduced to a scale; fertile floret pubescent | 7 | |
| 7. | Glumes drawn to a point at apex | *P. minor (NSW VIC TAS SA WA QLD) |
| Glumes not drawn to a point at apex | *P. aquatica (NSW VIC TAS SA WA QLD) P. tuberosa, P. tuberosa var. stenpotera |
Key to Phalaris derived from Anderson 1961; Vickery 1975
Taxonomic name: