The New Zealand Plant Conservation Network

Species

Scirpus polystachyus

Current Conservation Status

2012 - Non Resident Native - Coloniser

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 - Non Resident Native - Coloniser
2004 - Non Resident Native - Coloniser

Qualifiers

2012 - SO
2009 - SO

Authority

Scirpus polystachyus F.Muell.

Family

Cyperaceae

Flora Category

Vascular - Native

Structural Class

Sedges

Synonyms

None

Distribution

Indigenous. In New Zealand known only on the West Coast of the South Island, mainly in wetland south of Hokitika to about Okarito. Its range is still expanding. Common in Australia.

Habitat

Coastal to low lying fertile to moderately acidic open wetlands, lake, pond and slow flowing stream margins. Usually in well lighted places, often with its basalt stems and rhizomes immersed in water.

Features

Semi-aquatic to terrestrial summer green sedge forming robust leafy clumps up to 1.8 m tall. Stems more or less triquetrous, basally very leafy, with 3-5(-8) evenly spaced, cauline leaves. Leaves numerous, much < stems, 0.4-0.8 m x 5-8 mm, basally channelled but becoming flattened in upper half, strongly keeled, margins and keel finely scabrid; sheaths light reddish-brown, lustrous. Inflorescence a terminal compound, irregular, fan-shaped, umbel bearing many unequal erect rays; secondary rays slender, more or less drooping at maturity; leaf-liek bracts c.3, > inflorescence, upper bracts dark brown, strongly nerved. Spikelets more or less 4 mm long, ovate, in clusters of 2-5 at tips of rays. Glumes more or less 1.5 mm long, light brown to live, membranous, much darker towards apex, midrib thickened, not excurrent. Hypogynous bristles many, filiform, much > nut, folded, twisted or spiralled, very conspicuous at maturity. Stamens 3. Stigmas 3. Nut more or less 0.7 mm long, more or less trigonous but dorsal angle not well marked, cream.

Similar Taxa

None. However, in its vegetative state it can be confused with Bolboschoenus spp. which differ by their bulbous root stock, distinctly triquetrous stems, and by the leaves evenly spaced from the stem base to the inflorescence. Flowering material is very different as S. polystachyus has a distinctive, densely and many flowered, fan-shaped umbel, those of Bolboschoenus either lack rays or have up to 3 short rays bearing up to 4 spikelets, subtending by a sessile mass of 3-4 spikelets.

Flowering

September - February

Fruiting

December - June

Propagation Technique

Grows easily from fresh seed and rooted pieces. Has some potential as a pond ornamental. Requires full sun to flourish

Threats

Not Threatened but still very localised in its distribution. Because the first gatherings were made from near plantation forestry this species has been regarded as a weed introduced from Australia (Healy & Edgar 1980). The alternative, that it naturally arrived here by wind or avian dispersal was not considered at the time. This species has seeds suited to bird dispersal and it is not associated with plantation forestry in Australia. Its distribution in New Zealand overlaps with that of grey teal which feed in areas it frequents and are known to move between countries, so are a suitable seed vector. Therefore de Lange et al. (2009) treated it as a successful trans-Tasman colonist that while still uncommon is now actively spreading.

Chromosome No.

2n = 60

Endemic Taxon

No

Endemic Genus

No

Endemic Family

No

This page last updated on 19 Jan 2014