Carex chathamica


Carex: Latin name for a species of sedge, now applied to the whole group.
chathamica: From the Chatham Islands

Common Name(s)

Chatham Sedge

Current Conservation Status

2012 - At Risk - Naturally Uncommon

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

2009 - At Risk - Naturally Uncommon
2004 - Sparse


2012 - IE, RR, Sp
2009 - IE


Carex chathamica Petrie



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





Endemic. Chatham Islands where present on Chatham (Rekohu), Pitt, and South East Islands.


Predominantly found in peaty ground such as bogs, in wet clearings, at the margins if streams, lakes and ponds, and in swamps.


Rhizomatous, short-creeping, stoutly tufted, dark green to orange green, leafy sedge of peat bogs and swampy ground. Rhizomes woody up to 10 mm thick, loosely covered in fibrous brownish-grey sheath remnants. Culms 0.05-0.35-1 m x 1.5-3-6 mm. trigonous, smooth, stout and sturdy; basal sheaths light- to chestnut brown. Leaves not overtopping inflorescence, 6-8-10 mm wide, dark green to light green above, paler beneath, double-folded, margins slightly thickened, distinctly though finely serrate, especially toward the tapering apex; base of leaf neither sheathing or enlarged but marked by a distinct purple ligule. Inflorescence of 6-8(-12) simply, light brown spikes; uppermost 2-4 spikes male, these shorter and more slender than the female, more or less approximate; remaining spikes female with a few males near apices, 30-75(-90) x 10-15(-20) mm, erect on stout peduncles, both spikes and peduncles reducing in size toward distal end of inflorescence; subtending bracts leafy, > inflorescence, almost enclosing the peduncles with their sheaths. Glumes > utricles, linear-lanceolate, emarginated or entire, faintly nerved, membranous, light brown to dark brown or red purple (sometimes almost black), paler towards the margins, midrib pale brown prolonged as a long hispid awn. Utricles 3-4.5 x 2 mm, unequally biconvex, obovoid, turgid, pale green to brownish green, lateral nerves well-marked, otherwise smooth, margins glabrous, abruptly contracted to a narrow, deeply bidentate beak, slightly > 0.5 mm long, crura finely scabrid; stipe 0.5 mm long, white. Stigmas 3. Nut 2 mm long, pale grey-brown, trigonous, oblong-obovoid.

Similar Taxa

Carex chathamica is a distinctive species of peat bogs and peaty open clears within forest. From the three other wide-leaved species of Carex, (C. trifida Cav., C. ternaria Boott in Hook.f., and C. ventosa C.B.Clarke in Cheeseman) present in the Chatham Islands. C. chathamica is ecologically separated from all but C. ternaria. C. ternaria is a species of lake margins, slow flowing streams, ponds and permanent pools within peat bogs, its range rarely overlaps with C. chathamica from which it can be easily distinguished by its much greater stature (up to 3 m tall) and by its solitary rather than geminate basal spikes. Though ecologically distinct from the forest dwelling C. ventosa, herbarium specimens have been confused. Thus, C. chathamica can be distinguished from C. ventosa by its distinctly long-rhizomatous tufted, rather than shortly rhizomatous tussock forming habit, dark green to orange green rather than light green to pale glaucous green leaves, glumes which exceed rather than equal the utricles in length, and much less distinctly nerved and beaked utricles.


October - December


November - March

Propagation Technique

Best grown in permanently damp, peaty soils. Does well in cool, shaded sites, and is ideal around ponds or bordering streams. In the northern plant of New Zealand it has proved difficult to maintain and dislikes long periods of drought, humidity or both.


A biologically sparse species that is widespread, though never abundant on the Chatham Islands. In some places it is threatened by grazing and disturbance by stock and feral pigs.

Chromosome No.

2n = c.64

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Nuts surrounded by inflated utricles are dispersed by granivory and wind (Thorsen et al., 2009).

Where To Buy

Not commercially available


Description adapted from Moore and Edgar (1970).

References and further reading

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 2009 Vol. 11 No. 4 pp. 285-309

This page last updated on 29 May 2014