Isolepis cernua var. cernua
Isolepis pygmaea (Vahl) Kunth; Scirpus cernuus Vahl; Fimbristylis pygmaeum Vahl
Vascular – Native
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
2n = 48
Current conservation status
The threat classification status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – a suggested threat classification status has not been assessed by the NZTCS panel.
2017 | Not Threatened | Qualifiers: SO
Previous conservation statuses
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Indigenous. New Zealand. Almost cosmopolitan but apparently absent from S.E. Asia.
Mostly coastal on damp sand, or peat within sand flats, dune slacks, fringing lagoons and slow flowing brackish water, on coastal rocks and boulder beaches. More rarely inland around lake margins, and in peat bogs (especially restiad bogs)
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland).
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Variable in size, in dense tufts or with a shortly branched ascending rhizome. Culms 20-200 mm long, usually c. 0.5 mm. diameter or less, but occasionally up to 1 mm diameter Leaves 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. Inflorescence of 1–(2–3) spikelets; subtending bract ± = or usually slightly > spikelets, 3–25 mm long, setaceous or leaf-like, caducous. Spikelets 2.0–5.0 × 1.0–2.5 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, membranous, rounded towards the tip, or with the keel at tip of glume somewhat thickened and ± excurrent, lateral nerves conspicuous. Hypogynous bristles 0. Stamens 3, rarely 2 or 1 in occasional glumes. Style-branches 3. Nut us. slightly < 1 mm. long, but occasionally slightly > 1 mm., c.0.5 mm. wide, obovoid or occasionally 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.
An extremely variable species, I. cernua is generally easily recognised by its preference for coastal habitats (but it can occur well inland as well); leaves usually < culms; stamens mostly 3 per glume, trigonous red-brown or dark brown nut; and by the glume margins and nut with are rounded toward the apex.
August - December (may be present throughout the year)
October - May (may be present throughout the year)
Nuts are dispersed by water and possibly granivory and attachment (Thorsen et al., 2009).
Easily grown from fresh seed and by division of whole plants. Once established rather tolerant of a range of conditions but flourishes best in full sun in a permanently damp soil. An attractive pot plant.
isolepis: From the Greek isos (equal) and lepis (scale)
Description from Moore and Edgar (1970).
References and further reading
Johnson, A. T. and Smith, H. A (1986). Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd: Buckenhill, UK.
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.
Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309