Species

Ruppia megacarpa

Etymology

Ruppia: Named after Heinrich Bernhard Ruppius (1689-1719), an 18th century German botanist

Common Name(s)

horses mane weed, lakeweed

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 - Not Threatened
2004 - Not Threatened

Qualifiers

2012 - RR, SO

Authority

Ruppia megacarpa R.Mason

Family

Ruppiaceae

Flora Category

Vascular - Native

NVS Species Code

RUPMEG

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

Monocotyledonous Herbs

Synonyms

None

Distribution

Indigenous. North, South and Chatham Islands. Present in Australia

Habitat

Saline ponds, lagoons and slow flowing brackish streams. Predominantly coastal but occasionally extending inland

Features

Rhizome undistinguished; stems rather long usually with abundant zigzag branching. Leaves (40–)100–150(–200) × (0.2–)0.4–0.5(-0.7) mm, bright to olive green, almost filiform but broad-oblong in cross-section; apex bidentate, often most minutely denticulate; sheath (10–)15–25(-40) mm long, auriculate. Peduncles to 0.3 m long, usually reddish, scarcely thicker below flowers, becoming spirally coiled as fruit matures. Flowers protandrous; carpels 4, occasionally 5–6 in upper flower. Podogynes stout, tapering towards base. Achenes 40–45(–50) mm long, gibbous, olive-green, sometimes red-punctate; mesocarp thick; endocarp tuberculate, black, with 2 triangular apertures opposite to and about on level of top of operculum; beak c.1.3 mm long.

Similar Taxa

Ruppia polycarpa differs from R. megacarpa by its curved to straight rather than zig-zagged branching pattern, obtuse rather than bidentate leaf apices; carpels usually 4 per flower (rather than (5-)8(-16)), and fruits which are 4-5 mm long rather than < 3 mm long. Stuckenia pectinata which sometimes grows with both species of Ruppia is superficially similar. It is easily distinguished from both Ruppia species by the ligulate acute-tipped leaves, tuberous stems, and spicate inflorescences.

Flowering

October - February

Fruiting

November - April

Propagation Technique

Uncertain. Probably easily grown in suitable conditions but Ruppia is unlikely to be widely cultivated (if at all). Most people regard it as a pest and are only interested in eradicating it.

Threats

Not Threatened

Chromosome No.

2n = 20

Endemic Taxon

No

Endemic Genus

No

Endemic Family

No

Where To Buy

Not commercially available




Attribution

Fact sheet prepared for NZPCN by P.J. de Lange 2 March 2011. Description adapted from Moore & Edgar (1970).

References and further reading

Moore, L.B.; Edgar, E. 1970: Flora of New Zealand Vol. II. Wellington, Government Printer. 

This page last updated on 11 Aug 2014