Juncus acutiflorus Ehrh. ex Hoffm.

Tall-growing, in loose clumps or in diffuse colonies, sometimes in radiating lines of stems; rhizome stout, far-extending. Stems 30–100 cm high, stiffly erect, without internal transverse septa below inflorescence. Leaves ± compressed, conspicuously transversely-septate across whole width. Inflorescence 1–12 cm long, open, diffuse and spreading, much-branched with numerous small dark brown clusters of 3–12 flowers at end of branches, secondary branches diverging at an acute angle. Tepals 2–2.5 mm long, lanceolate, long-acuminate, outer < inner, often with recurved tips. Stamens 6. Capsule c. 3 mm long, > tepals, gradually tapering to an acute point, red-brown.

[From: Healy and Edgar (1980) Flora of New Zealand. Volume 3.]