The New Zealand Plant Conservation Network

Species

Gahnia rigida

Etymology

Gahnia: after Gahn
rigida: rigid

Common Name(s)

Gahnia

Current Conservation Status

2012 - Not Threatened

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 - Not Threatened
2004 - Not Threatened

Authority

Gahnia rigida Kirk

Family

Cyperaceae

Flora Category

Vascular - Native

NVS Species Code

GAHRIG

Structural Class

Sedges

Synonyms

Gahnia robusta Kirk; Gahnia rigida Kirk car. robusta (Kirk) Benl

Distribution

Endemic. North (near Pureora, Mamaku Plateau, Mangaroa Swamp) and South Islands (western Nelson and Westland to about Haast).

Habitat

Coastal to lowland in swamps, bogs, mires and pakihi - often forming the dominant cover.

Features

Robust perennial sedge arising from a stout, lignaceous rootstock and forming dense yellow-green tussocks 0.6-2.2 m tall. Culms 4-6 mm diameter (but up to 10 mm diameter near base). Leaves up to 3 m long, mostly erect with apices slightly drooping; sheaths dull pinkish brown, open, often frayed or shattered up to 50 mm wide at the base; lamina very hard, scabrid right across undersides, margins strongly involute when dry, scabrid; lamina when dry becoming undulate for some distance above the transverse line demarcating sheath from lamina. Panicle rigid, 18--760 x 60 mm, bearing numerous stiffly erect branchlets, primary branchlets up to 250 mm long. Spikelets 2-flowered, 6-7 mm long, stalked, light chestnut-brown to dark brown. Glumes 6-7; 3-4 outer glumes 6-7 mm long, empty; 3 inner glumes enclosing fruit brown. Stamens 4-5. Style-branches (2-)4. Nut 3.5-4.0 x 1.5-2.0 mm, ellipsoid-obovoid, usually light red-brown with a band of dark brown round the centre or the upper half dark brown, occasionally dark brown at the base and apex and then almost black at the centre, tipped with a fine scabrid point; endocarp transversely grooved within.

Similar Taxa

Gahnia rigida could only ever be confused with the other giants of the New Zealand species G. setifolia (A. Rich.) Hook.f. and G. xanthocarpa (Hook.f.) Hook.f. Gahnia rigida rarely grows with either of these species. Gahnia xanthocarpa differs from G. rigida by its glossy light to dark green leaves, drooping rather than rigidly erect panicles, and dark glossy black nuts. Gahnia setifolia differs from G. rigida also by its drooping rather than rigidly erect panicle and reddish brown nuts. The nuts of G. rigida are diagnostic being the only ones to be consistently bicoloured light red-brown/dark brown, or dark brown with a broad black central band present

Flowering

December - March

Fruiting

Fruits may be found throughout the year

Propagation Technique

Can be difficult to cultivate. The seed is difficult to germinate, and plants resent root disturbance and usually die if transplanted. However, considerable success has been achieved growing plants and/or germinating seed in untreated saw dust. Despite these problems this is an attractive species well worth attempting to grow. Once established it flourishes in a range of conditions though it does best in full sun in an acidic, poorly drained soil.

Threats

Not Threatened

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Life Cycle and Dispersal

Florets are wind dispersed (Thorsen et al., 2009).

This page last updated on 20 Nov 2015