| 1. | Culms decumbent, rooting at nodes | *M. maximus var. maximus cv. Embu (QLD) |
| Culms tufted and erect, not rooting at nodes | 2 | |
| 2. | Spikelets indistinctly hairy | *M. maximus var. pubiglumis (NSW QLD) Urochloa maxima var. trichoglume |
| Spikelets glabrous | 3 | |
| 3. | Leaf hairy at junction of sheath and blade | *M. maximus var. coloratus (QLD) Urochloa maxima var. coloratum |
| Leaf glabrous at junction of sheath and blade | 4 | |
| 4. | Plant 1.8-2 m tall; leaf-blades 15-18 mm wide | *M. maximus var. maximus (NSW NT SA WA QLD) Urochloa maxima var. maxima |
| Plant 3-3.5 m tall; leaf-blades 24-26 mm wide | *M. maximus var. maximus cv. Hamil (QLD) |
Key to Megathyrsus derived from
Taxonomic name: