Description: Slender tufted or spreading perennials.
Leaves with ligule membranous, entire but becoming lacerated with age; blade flat or inrolled.
Inflorescence a narrow, loose, elongated panicle, branches erect, slender, often flexuous.
Spikelets pedicellate, solitary, rachilla disarticulating above the glumes and between the lemmas and usually produced as a bristle beyond the uppermost floret; florets 3–10, bisexual (or the uppermost male). Glumes obtuse or acute, keeled or rounded on the back, the upper broader. Lemmas exserted from the glumes, 2–4-toothed, prominently 5–7-nerved, awned dorsally from c. the middle of the back, the awn bent and slightly twisted (sometimes geniculate), callus prominent, usually with silky hairs. Palea shorter than the lemma, with 2 ciliate keels and bilobed apex.
Distribution and occurrence: World: 12 species, Australia, New Zealand, southern Amer, aquatic or semiaquatic. Australia: 10 species (native), all States except N.T.
Text by S. W. L. Jacobs & S. M. Hastings
Taxon concept:
| | Key to the species | |
| 1 | Plants stoloniferous; lemmas with straight awns | 2 |
| Plants not stoloniferous, tufted; lemmas with bent and often twisted awns | 3 |
| 2 | Spikelets 12–21 mm long; lemmas more than 6 mm long; florets 5–7 | Amphibromus sinuatus |
| Spikelets 9–15 mm long; lemmas less than 6 mm long; florets 6–10
Back to 1 | Amphibromus fluitans |
| 3 | ligule 5 mm long or less; lemmas swollen | Amphibromus pithogastrus |
| ligule 6 mm long or more; lemmas not swollen
Back to 1 | 4 |
| 4 | Awn arising near the lemma tip, from top 30% of lemma length; lemma apex appearing constricted | Amphibromus neesii |
| Awn dorsal, arising from bottom 60% of the lemma length; apex of lemma not appearing constricted
Back to 3 | 5 |
| 5 | Back of lemma very roughly papillose; awn arising 50–60% of the lemma length from apex which is drawn out, papery | Amphibromus macrorhinus |
| Back of lemma smooth or scabrous; awn arising 40–50% of lemma length from apex which tapers evenly
Back to 4 | Amphibromus nervosus |
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