Species

Myriophyllum propinquum

Etymology

Myriophyllum: many leaves
propinquum: very like the next species

Common Name(s)

Common water milfoil

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

Myriophyllum propinquum A.Cunn.

Family

Haloragaceae

Flora Category

Vascular - Native

NVS Species Code

MYRPRO

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

Dicotyledonous Herbs other than Composites

Features

Weak aquatic or semiaquatic or terrestrial herb (50-)100-250(-400) mm tall; stems weak, slender, 1.0-1. 5(-3.0) mm diameter, rooting at lower nodes; glabrous. Leaves distinctly dimorphic. Submerged leaves in whorls of 3-4(-5), ovate to orbicular in outline, (6-)10-20(-25) × 10-16(-25) mm, pectinate with 10-22 filiform pinnae 5-6(-20) mm long, with distinct petiole 1-2 mm long. Emergent leaves in whorls of (2-)3-4(-5), linear, (2-)5-7(-12) × 0.5-1.0(-1.5) mm, usually flattened but occasionally terete to filiform, spreading or slightly curved upwards, margin entire or sometimes weakly toothed. Rarely, all or most emergent leaves pinnatifid, 4-5 ×1.5-3.5 mm wide with pinnae to 1.5 mm long. Transitional leaves usually 1-2(-4) whorls only. Inflorescence an indeterminate spike with the unisexual flowers borne singly in axils of the emergent leaves. Each whorl contains flowers of 1 sex only, male in upper 1-8 whorls, female in lower 2-6 whorls, with usually 1-2 sterile whorls between. Occasionally all whorls (up to 20) contain female flowers only. All flowers subtended by 2 bracteoles. Bracteoles ovate, (0.4-)0.5-0.8 × (0.2-)0.4-0.5 mm wide, slightly laciniate towards tip or entire. Male flowers 4-merous, sessile or becoming shortly pedicellate. Sepals 4, ovate, 0.4-0.6 × 0.3-0.4 mm, weakly toothed near apex. Petals 4, hooded, very weakly keeled, 1.8-2.7(-3.0) × 1.4 mm, becoming reflexed and inrolled after anthesis. Stamens 8; filaments 1-2 mm long, elongating after anthesis; anthers yellow, linear-oblong, 1.7-2.4 × 0.4-0.5 mm, antisepalous anthers c. 0.2 mm longer than antipetalous ones. Styles 0. Ovary vestigial. Female flowers 4-merous, sessile. Sepals, petals and stamens 0. Styles 4, clavate, 0.2-0.3 mm long, stigmas occupying most of length of style, white, fimbriate. Ovary 4-merous, oblong, 0.7-0.8 mm long (excluding styles), 0.7 mm wide; carpels cylindrical, smooth, with styles on outermost corners. Fruit pale yellow-brown, cylindrical, sessile, splitting at maturity into 4 mericarps. Mericarps 0.8-1.1 mm long, 0.4-0.5 mm diameter, smooth apart from scattering of very small asperities on outer face, crowned by persistent base of style.

Flower Colours

White,Yellow

Propagation Technique

Easily grown from fresh seed and rooted pieces. An excellent plant for pond, slow flowing stream or fish tank.

Threats

Not Threatened

Chromosome No.

2n = 14

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Attribution

Fact Sheet Prepared by P.J. de Lange (1 November 2009). Description based on Orchard (1979)

References and further reading

Orchard, A.E. 1979: Myriophyllum (Haloragaceae) in Australasia. 1. New Zealand: a revision of the genus and a synopsis of the family. Brunonia 2: 247-287.

This page last updated on 6 Dec 2014