Carex geminata
Common name
Cutty grass, Rautahi
Synonyms
Carex ternaria var. gracilis Cheeseman, C. confusa Hamlin.
Family
Cyperaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Sedges
NVS 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.
CARGEM
Current conservation status
The conservation 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). 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.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Distribution
Endemic. Found throughout the North, South and Stewart Islands.
Habitat
Coastal to lower montane in freshwater wetlands, along river and stream banks, lake margins, and in damp seepages, pond margins and clearings within forest. Preferring fertile to mid-fertile wetlands.
Features
Rhizomatous, robust bright-green to yellow-green sedge, 0.5-1.2 m tall. Culms 1-5-3.5(-5) mm diam., triangular in cross-section, very sharply scabrid. Basal sheaths dull grey-brown or purple-brown. Leaves numerous, > culms (2-)5-9(-11), wide, double-folded, margins very scabrid. Spikes (10-)15-24, yellow-green, grass-green, or dark-green mottled red or purple, all pedunculate, pendulous, rather narrow, often twisted and “worm-like”. Glumes dark red-purple, (excluding awns) more less same length as utricles, narrow-oblong, truncate or emarginate with a hispid awn of variable length. Utricles (2-)2.3-2.9(-3.5) x 1.2-1.7(-2) mm, biconvex, compressed at base, tapering evenly above, green-, red- or yellow-brown, 3-5-nerved, margins glabrous, beak minute or 0.2 mm long.
Similar taxa
C. geminata has frequently been confused with C. lessoniana Steud. This species often grows in similar habitats, but can be distinguished by the compact inflorescences, with wider, though smaller, usually erect spikelets, and by distinctly beaked utricles. A similar species C. ternaria Boott is occasionally cultivated on the New Zealand mainland, this species is very much larger (up to 3 m tall), dark green sedge with much larger spikes and glumes which are conspicuously awned.
Flowering
(September-) October-November (-December)
Fruiting
October - March
Life cycle
Nuts surrounded by inflated utricles are dispersed by granivory and wind (Thorsen et al., 2009).
Propagation technique
Easily grown from fresh seed and by the division of established plants. Although a wetland species C. geminata will grow well in most soils and moisture regimes. Does best in full sun.
Etymology
carex: Latin name for a species of sedge, now applied to the whole group.
geminata: Twinned
Where To Buy
Not commonly cultivated, and plants offered by this name by many nurseries are usually other quite unrelated species, including the Northern Hemisphere C. pendula and the New Zealand subantarctic endemic C. ternaria.
Notes on taxonomy
This taxon includes two entities, one probably better regarded as an allied but distinct, possibly unnamed species which differs from true C. geminata by its much broader, often yellow-green leaves, longer narrower spikelets, preference for open sunny sites within coastal and lowland wetlands, and also by distinct differences within the nrDNA ITS sequence region.
Attribution
Fact Sheet prepared by P.J. de Lange (10 August 2006). 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
Citation
Please cite as: de Lange, P.J. (Year at time of access): Carex geminata Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/carex-geminata/ (Date website was queried)