| 1. | Plant prostrate; inflorescence spikes and leaf blades up to 1.1 cm long | B. prostrata (NT WA QLD) |
| Plant erect or stoloniferous; inflorescence spikes and leaf blades more than 2 cm long | 2 | |
| 2. | Lemma and palea with a subapical tuft of hairs | B. ciliaris (NSW NT SA QLD) |
| Lemma and palea hairy to some degree but without a subapical tuft | 3 | |
| 3. | Glumes 3.5-4.5 mm long; leaf sheath auricles bearded | B. convergens (NSW NT SA QLD) |
| Glumes 2-3 mm long; leaf sheath auricles glabrous | 4 | |
| 4. | Grain laterally compressed; glumes acute | B. ambigua (NT WA) |
| Grain ellipsoid; glumes sub-obtuse | B. tenella (NSW WA QLD) |
Key to Brachyachne derived from Lazarides 1972; Nightingale et al 2005
Taxonomic name: