| 1. | Spikelets 1.5-3mm long | 2 |
| Spikelets less than 1.5mm long | 3 | |
| 2. | Glumes glabrous and rounded at apex |
I. globosa (NSW VIC NT SA WA QLD) I. australis |
| Glumes covered with bristles and pointed at apex | I. sharpii (QLD) | |
| 3. | Upper glume hairy; upper lemma glabrous; perennial | I. confusa (NT QLD) |
| Upper glume glabrous; upper lemma hairy; annual |
*I. minutula (NT WA QLD) I. miliacea, I. brassii, I.pulchella auct. |
Key to Isachne derived from Henty 1969; Webster 1987
Taxonomic name: