Gahnia xanthocarpa

Species

Gahnia xanthocarpa

Etymology

Gahnia: after Gahn
xanthocarpa: yellow fruit

Common Name(s)

Gahnia, mapere

Current Threat Status

2012 - Not Threatened

Previous Threat Status

2009 - Not Threatened
2004 - Not Threatened

Authority

Gahnia xanthocarpa (Hook.f.) Hook.f.

Family

Cyperaceae

Flora Category

Vascular - Native

Synonyms

Lampocarya xanthocarpa Hook.f.; Gahnia ebenocarpa Hook.f. ex Kirk; Claudium xanthocarpum (Hook.f.) F.Muell.; Gahnia setifolia (A.Rich.) Hook.f. var. xanthocarpa (Hook.f.) Kük.

Distribution

Endemic. North Island (from Te Paki south to Wellington but uncommon, or absent over some parts of this range), South Island (Nelson, Marlborough, Westland and Canterbury - where it is very uncommon).

Habitat

Coastal to montane (up to 800 m a.s.l. - possibly more). Occupying a diverse range of habitats and vegetation associations, Gahnia xanthocarpa seems to prefer permanently damp situations within alluvial forest, swamp forest and the margins of lowland swamps, bogs and waterways

Features

Robust perennial sedge arising from a lignaceous rootstock up to 30 mm diameter and forming densely tufted dark green tussocks up to 3.5 m tall. Culms 10 mm diameter (but up to 15 mm diameter at the base). Leaves = to or slightly < culms, not usually overtopping the panicle; lamina dark glossy green above, paler beneath, surfaces harshly scabrid, margins involute, ciliate just above the transverse line demarcating the sheath from the lamina, becoming more intensely scabrid higher up with a few longitudinal rows of teeth just inside the margin on the lamina undersides; sheaths dull, light pinkish brown, glabrous up to 40 mm wide. Panicles set well above foliage, drooping, 0.6-1.5 m long, heavily branched, primary branchlets up to 450 mm long. Spikelets 2-flowered, c.8 mm long, numerous, densely crowded, stalked, light chestnut-brown. Glumes 6-7; outer 3-4 empty, more or less equal, 7-8 mm long; inner 3 glumes smaller, 5-6 mm long, red-brown, or green-brown below and red brown towards apices. Stamens 4, bright red-brown. Style-branches 3-4. Nut 5-6 x 2-3 mm, fusiform, bright yellow maturing glossy black when fully ripe, sometimes slightly grooved, shortly stipitate, with alight orange-brown, obtuse, pubescent apex; endocarp transversely grooved within.

Similar Taxa

Gahnia xanthocarpa could only ever be confused with the other giants of the New Zealand species G. setifolia (A. Rich.) Hook.f. and G. rigida Kirk. Gahnia xanthocarpa frequently grows G. setifolia from which it is easily distinguished by its glossy dark green leaves, reddish brown spikelets which are > 7 mm long and dark glossy black nuts which are > 5 mm long. Gahnia xanthocarpa rarely grows with G. rigida from which it is easily distinguished by its drooping rather than rigidly erect panicle and dark glossy black nuts

Flowering

January - April

Main Flower Colour

Red / Pink

Other Flower Colour

Brown

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 but does best planted in a permanently damp, humus-rich soil.

Threats

Not Threatened

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Cultural Use/Importance

There seems to be no basis for records of this species from Fiji and the New Hebrides. Lord Howe plants have recently been separated as a distinct endemic species Gahnia howense R.O.Gardner.

Notes on etymology

The specific epithet xanthocarpa literally 'yellow-fruit' is inappropriate and was given by accident because the type material is of a specimen J.D. Hooker did not realise was bearing immature nuts which in this species are bright yellow. When the nuts of this species mature they are diagnostically dark glossy black.  

References and further reading

Gardner, R.O. 1995. Identifying Gahnia setifolia and G. xanthocarpa. Auckland Botanical Society Journal, 50: 82-83.

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 20 Nov 2015

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