Carex riparia Curtis

Tufted, to 90 cm high. Rhizome far-extending, stout with fibrous grey-brown scales. Stems sharply 3-angled, scabrid on angles just below inflorescence. Leaves > stems, to 15 mm wide, rigid, erect, channelled to double-folded, blue-green, minute cross-veinlets very distinct when dry; sheaths very long, bright reddish to whitish, distinctly septate-nodulose. Inflorescence with longer, narrow, leaf-like bracts below; spikes numerous, erect, brown. Male spikes 3–4, crowded, 2–6 cm × 5–10 mm, tapered above to a point; glumes very narrow-lanceolate, acuminate or with excurrent midrib. Female spikes 2–4, occasionally male at top, 6–11 × 1–1.2 cm, fusiform, upper sessile, lower pedunculate; glumes > utricles, lanceolate with midrib long-excurrent. Utricles 5–5.5 × 2 mm, with numerous fine nerves, glabrous, dull grey-brown, subtrigonous, ovate, gradually tapered to a bifid beak ± 1 mm long. Stigmas 3. Nut oblong-ovoid, trigonous, shortly stipitate.

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