| 1. | Lower glume more than 1/3 spikelet length | 2 |
| Lower glume 1/8-1/3 spikelet length | 24 | |
| 2. | Lower floret male | 3 |
| Lower floret sterile | 4 | |
| 3. | Spikelets 5.5-7 mm long, densely pilose | *P. racemosum (NSW VIC) |
| Spikelets to 3.5 mm long, glabrous | *P. antidotale (NSW SA WA QLD) | |
| 4. | Spikelet 5-6.5 mm long, apex obtuse | *P. miliaceum (NSW VIC TAS SA WA QLD) |
| Spikelet less then 5 mm long or if 5 mm long then apex mucronate | 5 | |
| 5. | Lower glume obtuse to sub-acute (NEEDS CHECKING for P. trichoides and P.incomtum) | 6 |
| Lower glume acute to acuminate | 8 | |
| 6. | Lower glume less than half spikelet length |
*P. luzonense (NT) P. cambogiense |
| Lower glume at least half spikelet length | 7 | |
| 7. | Spikelets 0.8-1.4 mm long | *P. trichoides (NT WA QLD) |
| Spikelets more than 2 mm long | *P. incomtum (QLD) | |
| 8. | Lower glume at least 3/4 spikelet length | 9 |
| Lower glume 1/2-2/3 spikelet length | 14 | |
| 9. | Lower glume ±equal to spikelet length or longer | 10 |
| Lower glume shorter than spikelet | 11 | |
| 10. | Spikelet 2.5-3 mm long |
P. mindanaense (NT WA QLD) P. delicatum |
| Spikelet at least 4 mm long |
P. trachyrhachis (NT WA QLD) P. robustum |
|
| 11. | Annual; inflorescence branches flexuous | 12 |
| Perennial; inflorescence branches divaricately spreading | 13 | |
| 12. | Leaves glabrous | P. seminudum var. seminudum (NT WA QLD) |
| Leaves hairy | P. seminudum var. cairnsianum (NT QLD) | |
| 13. | Spikelets 3-4.5mm long; fertile floret 2.5-2.75 mm long | P. queenslandicum var. queenslandicum (NSW QLD) |
| Spikelets 5-7mm long; fertile floret 3-3.5 mm long | P. queenslandicum var. acuminatum (NSW) | |
| 14. | Palea absent in lower floret | 15 |
| Palea present in lower floret | 17 | |
| 15. | Decumbent and glabrous; rooting at nodes | P. bisulcatum (NSW VIC QLD) |
| Tufted; leaves with tubercle-based hairs; not rooting at nodes | 16 | |
| 16. | Spikelets 2-2.5 mm long | *P. capillare var. capillare (NSW VIC SA WA) |
| Spikelets 2.5-3.3 mm long |
*P. capillare var. brevifolium (NSW VIC TAS) P. capillare var. occidentale |
|
| 17. | Fertile lemma with a lunate scar at base | *P. hillmanii (VIC TAS SA) |
| Fertile lemma without a lunate scar at base | 18 | |
| 18. | Upper glume and lower lemma 9-nerved | 19 |
| Upper glume and lower lemma 5-7-nerved | 20 | |
| 19. | Tufted perennial; leaves with silky hairs | P. bombycinum (QLD) |
| Decumbent annual; leaves with tubercle-based hairs | *P. novemnerve (QLD) | |
| 20. | Culm internodes and base distinctly hairy | P. effusum (NSW VIC NT SA WA QLD) |
| Culm internodes and base glabrous or slightly hairy | 21 | |
|
21. 22. |
Inflorescence a fairly narrow panicle, with spikelets thinly dispersed in the inflorescence and occupying less than half the height of the culm ; spikelets acute | 22 |
| Inflorescence a large open panicle, with many spikelets occupying at least half the height of the culm; spikelets acuminate | 23 | |
| Secondary inflorescence branches poorly developed; sandstone soil |
P. simile (NSW VIC NT QLD) P. fulgidum, P. effusum var. simile |
|
| Secondary inflorescence branches well developed; clay soil | P. sp. A (NSW) | |
| 23. | Annual; inhabits limestone outcrops | P. chillagoanum (QLD) |
| Perennial; habitats other than limestone | P. mitchellii (QLD) | |
| 24. | Lower floret male | 25 |
| Lower floret sterile | 27 | |
| 25. | Annual |
*P. schinzii (NSW SA TAS WA) P. laevifolium |
| Perennials | 26 | |
| 26. | Rhizomatous; lower glume truncate to rounded | *P. repens (NSW WA QLD) |
| Tufted, with a swollen or knotty base; lower glume acute | *P. coloratum (NSW VIC WA QLD) | |
| 27. | Aquatic or swamp grasses | 28 |
| Non-aquatic grasses | 29 | |
| 28. | Rhizomes thick and spongy; spikelets acuminate | P. paludosum (NSW NT QLD) |
| Rhizomes slender; spikelets acute | P. obseptum (NSW VIC QLD) | |
| 29. | Prostrate grass with inflorescence up to 7 cm long | 30 |
| Tufted grass with panicles more than 7 cm long | 31 | |
| 30. | Spikelets less than 2 mm long | P. pygmaeum (NSW QLD) |
| Spikelets 2-3 mm long | P. lachnophyllum (NSW QLD) | |
| 31. | Upper floret somewhat shorter than spikelet | P. buncei (NSW SA QLD) |
| Upper floret ±equal to spikelet length | 32 | |
| 32. | Inflorescence branches ±flexuous, lower ones solitary | 33 |
| Inflorescence branches rigid and spreading, lower ones whorled | 35 | |
| 33. | Perennial | P. larcomianum (QLD) |
| Annual or biennial | 34 | |
| 34. | Upper glume 9-11-nerved; glumes with distinct rachilla between them |
*P. gilvum (NSW VIC QLD) P. laevifolium var. contractum, P. schinzii auct. |
| Upper glume 7-nerved; glumes without distinct rachilla between them |
P. laevinode (NSW NT SA WA QLD) P. whitei |
|
| 35. | Spikelets 2.5-2.8 mm long | P. decompositum var. tenuis (NSW NT QLD) |
| Spikelets 3-3.5 mm long | P. decompositum var. decompositum (NSW VIC NT SA WA QLD) | |
| Spikelets 3.5-4.1 mm long |
P. latzii (NSW WA QLD) P. decompositum var. acuminatissimum |
Key to Panicum derived from Vickery 1975; Webster 1987; Morris 1991; Simon 1992
Taxonomic name: