Centrolepis glabra (F.Muell. ex Sond.) Hieron.

Annual tuft, 4–30 mm high. Stem internodes condensed and not discernible. Leaves spiral, appearing radical, spreading. Leaf-sheath 1–3.5 mm long, hyaline, glabrous. Leaf-sheath auricles absent; aligulate. Leaf-lamina 2.5–24 × 0.4–0.5 mm, subulate, with an acuminate apex, terete to faintly compressed, glabrous. Uppermost leaf reduced to a membranous cataphyll. Flowering stems 1.5–14 mm long, glabrous. Inflorescence an ovoid spike, 3–4 × 0.8–1.4 mm. Outer primary floral bract 3.0–4 mm long, ovate and narrowing to a foliar point; papillate. Inner floral bract, 1.6–2.5 long mm, ovate; papillate. Internode between primary bracts absent. Secondary hyaline scales absent. Reproductive units/spike 3–6, 2 or 3 bisexual, the others female. Androecium 1 stamen; filament capillary, 2–4 mm long; anthers ellipsoid, 0.6–1 mm long. Gynoecium (2)–3–6 connate, superposed carpels. Styles stigmatic with simple papillae, crimson. Seeds, 0.5–0.6 × 0.24–0.3 mm, obovoid, yellow to yellow-brown or red-brown, faintly striated.

Distinguished from C. pallida, which is also glabrous, by a tufted habit with leaves appearing radical, whereas C. pallida forms tight cushions and has a distinctly distichous leaf arrangement. Also, C. glabra has a membranous cataphyll subtending the flowering stem, whereas in C. pallida a normal leaf subtends the flowering stem.

Associated with fluctuations of shorelines of kettlehole tarns and lakes in the montane to upper montane zone from 200 to 800 m a.s.l. Initially growing below the waterline in silt or sand, or in a sandy matrix of gravel and rock, then flowering and fruiting above the receding waterline during late summer and autumn.

Flowering: Mar.-May

New Zealand plants have slightly larger seeds and longer anthers than recorded from Australian plants (Cooke 1992).