Isolepis basilaris


Isolepis: From the Greek isos (equal) and lepis (scale)
basilaris: From Latin 'basis' borrowed originally from Greek, meaning basal

Common Name(s)

Pygmy clubrush

Current Conservation Status

2018 - At Risk - Declining

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2012 - Threatened - Nationally Vulnerable
2009 - Threatened - Nationally Endangered
2004 - Serious Decline


2012 - EF, RR, Sp
2009 - De


Isolepis basilaris Hook.f.



Flora Category

Vascular - Native

NVS Species Code


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.

Structural Class



Scirpus basilaris (Hook.f.) C.B.Clarke, Isolepis novae-zelandiae Colenso


Endemic. North and South Islands from Hawkes Bay to Southland.


Coastal, lowland to upland habitats, up to 700m altitude. On damp, sandy or silty margins of lagoons, tarns, ephemeral lakes and rivers, freshwater or brackish.


Minute, moss-like, densely tufted plant forming circular patches 10–100 mm diameter and up to 60 mm tall, bright green above, reddish brown below. Rhizome < 1 mm. diameter, much branched; sheathing bract at each node loose, membranous, with red nerves. Culms < 1.5 rarely up to 30 mm long, < 0.5 mm diameter. Leaves 1–2 on each branch, much > culms, 5–60 mm long, < 0.5 mm wide, setaceous, plano-convex; sheath membranous, red-nerved. Inflorescence an apparently lateral, single spikelet, or rarely 2, hidden among the leaves, pale green, occasionally with red markings; subtending bract leaf-like, channelled, very much > culm from which it arises and almost = leaves. Spikelets 2.5–3.5 x 1.5–2.0 mm, elliptical or oblong. Glumes 1–2 mm. long, ovate, elliptical, obtuse, white and membranous, or with patches of red on the sides; keel thick, green, occasionally slightly excurrent. Hypogynous bristles 0. Stamens 2-3. Style-branches 2-3. Nut c.0.5 × 0.5 mm, c. 2/3 length of glume, obovoid to suborbicular, plano-convex, dorsally rounded, noticeably apiculate, red-brown to dark brown, almost black, surface often shining but distinctly reticulate.

Similar Taxa

Isolepis caligenis. Isolepis basilaris has 1-2 leaves per tuft, very short flower stems with spikelets hidden amongst leaves and very dark brown nuts, flat on one side. I. caligenis has 2-5 leaves per tuft, longer flower stems and pearly grey nuts, rounded on both sides. Occasionally Isolepis basilaris with elongated flower stems is difficult to distinguish from I. caligenis if fruit is immature.


September to November


December to April (but seedheads long persistent)

Propagation Technique

Easily grown from fresh seed and division of whole plants.


Domestic and feral cattle, sheep, horses and pigs are the serious threats throughout this species range, mainly through browse, trampling, and facilitating the spread of weeds. Competition from taller vegetation is significant at many sites. Coastal development (e.g., road widening) and erosion are further common threats to most populations. In some locations plants are threatened by 4-wheel drive vehicles.

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Nuts are dispersed by water and possibly granivory and attachment (Thorsen et al., 2009).

Where To Buy

Not commercially available but plants are held by several Botanic Gardens and specialist growers.


Description adapted 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

This page last updated on 30 May 2015