Variable in size, in dense tufts or with a shortly branched ascending rhizome. Culms (2)–6–12–(20) cm. long, us. c. 0.5 mm. diam. or less, but occ. up to 1 mm. diam. Lvs 1–4 or 0, ± = culms, or much < culms, c. 0.5 mm. wide, or often reduced to shortly mucronate sheaths; sheaths dark red-purple at the base, lighter brown towards the truncate orifice. Infl. of 1–(2–3) spikelets; subtending bract ± = or us. slightly > spikelets, 0.3–0.7–(2.5) cm. long, setaceous or lf-like, caducous. Spikelets 2–5 × (1)–1.5–2.5 mm., elliptical, obtuse, almost white, or green, or with red-brown markings. Glumes 1–2 mm. long, broadly ovate, only slightly concave with keel not prominent, obtuse, green to very pale straw coloured, or with red-brown markings at the sides, margins entire, membr., rounded towards the tip, or with the keel at tip of glume somewhat thickened and ± excurrent, lateral nerves conspicuous. Hypog. bristles 0. Stamens 3, rarely 2 or 1 in occasional glumes. Style-branches 3. Nut us. slightly < 1 mm. long, but occ. slightly > 1 mm., c. 0.5 mm. wide, obovoid or occ. elliptical-obovoid, plano-convex, or subtrigonous and obtusely angled at the back, rounded at the tip and sharply apiculate, red-brown or dark grey at maturity, minutely but very distinctly reticulate.
[From: Moore and Edgar (1970) Flora of New Zealand. Volume 2 as Scirpus cernuus Vahl]