Tall-growing, loosely tufted or forming patches, stems occasionally in lines; rhizomes stout, far-extending. Stems 50-120 cm high, with 1-2 cauline leaves, internal transverse septa not present. Leaves hollow with longitudinal and transverse septa (in the recent N.Z. collections the longitudinal septa were not evident); cauline leaves with 35-60 evident transverse septa. Inflorescence to 15cm long, open, spreading and diffuse, with many small, 3-12-flowered clusters, secondary branches diverging at a wide angle (i.e. greater than 90º) or curved. Tepals c.2 mm long, blunt and incurved, hooded. Stamens 6. Capsule 2-2.5 mm long, scarcely > tepals, ovoid, trigonous, acuminate, short-beaked.