Description: Perennials, usually with several-noded, usually branching, culms or these simple with inconspicuous nodes and short internodes at the base of the elongate peduncle.
Leaves with ligule short; blade flat or involute, acuminate. Sometimes with cleistogenes in the basal sheaths.
Inflorescence a contracted or open panicle. Spikelets all alike, bisexual, 1-flowered with the rachilla disarticulating above the glumes and not prolonged beyond the floret. Glumes 3-nerved, lanceolate, acuminate, longer than the floret, subequal, persistent. Lemma often with a corona, the awn slightly and loosely twisted or slightly geniculate or flexuous, deciduous, sometimes eccentric, callus often pungent. Palea nerveless or 1-nerved, much shorter than the lemma, often hyaline. Stamens 3.
Distribution and occurrence: World: c. 80 species, Amer, chiefly in or near the Andes. Australia: 5 species (naturalized), N.S.W., Vic., Tas.
Text by S. W. L. Jacobs & J. Everett
Taxon concept:
| | Key to the species | |
| 1 | Summit of the lemma without a cylindrical corona; floret <3.5 mm long | 2 |
| Summit of the lemma forming a conspicuous cylindrical corona 0.5–2.5 mm long around the base of the awn; floret >3.5 mm long around the base of the awn | 3 |
| 2 | Awn 2–3.5 cm long; floret 1.5–2 mm long; inflorescence fully exserted and detaching at maturity | Nassella trichotoma |
| Awn 4.5–9 cm long; floret 2–3 mm long; inflorescence often only partly exserted from sheath, detactching or not detaching at maturity
Back to 1 | Nassella tenuissima |
| 3 | Floret c. 4 mm long; awn 35–40 mm long, column minutely scabrous with hairs less than 0.05 mm long | Nassella hyalina |
| Floret 5.5–10 mm long; awn 45–85 mm long, column scabrous or pubescent with hairs usually 0.2 mm long
Back to 1 | 4 |
| 4 | Lower glume 8–10 mm long; floret 5.5–6 mm long; coronal spines c. 0.1 mm long | Nassella megapotamia |
| Lower glume 14–18 mm long; floret 6–10 mm long; coronal spines c. 0.5 mm long
Back to 3 | Nassella neesiana |
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