Species

Myriophyllum triphyllum

Etymology

Myriophyllum: many leaves
triphyllum: three-leaved

Common Name(s)

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 triphyllum Orchard

Family

Haloragaceae

Flora Category

Vascular - Native

NVS Species Code

MYRELA

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

Synonyms

Myriophyllum elatinoides

Distribution

Endemic. New Zealand: North, South and Chatham Islands

Features

Weak aquatic herb; stems 50-100 cm long, rooting mainly at base, 1-2(-3) mm diameter; leaves dimorphic, verticillate. Submerged leaves in whorls of (2-)3(-4), ovate in outline, sessile (petiole 0.1-0.2 mm long), (6-)10-15 mm long, (5-)7-10(-15) mm wide, pectinate with 12-18 filiform pinnae 8 mm long. Leaves lacking hydathodes at base. Emergent leaves red-purple, in whorls of 3(-4), very rarely becoming alternate in upper part of inflorescence, narrowly ovate to obovate, (2.5-)5-6(-12) × (1.5-)2.0-2.5(-4.0) mm, entire (or those of lower whorls incised), obtuse, shorter than internodes at flowering. Transition from submerged to emergent leaves abrupt (1-2 whorls). Inflorescence all indeterminate spike, sometimes with 2-4 lateral inflorescences arising from axils of the upper whorl of submerged leaves. Flowers 4-merous, borne singly in axils of the emergent leaves, upper flowers male, lower ones female. Bracteoles cream, lanceolate, (1.0-)1.4-1.8(2.0) × (0.2-)0.3-0.4 mm, entire or minutely 3-4 toothed, acute. Male flowers. Sepals 4, cream, deltoid, 0.5-0.6 mm long, 0.4-0.5 mm wide, weakly 2-3-toothed. Petals 4, yellow to reddish, hooded, not or only very weakly keeled, 2.0-2.8 × 2.0 mm wide. Stamens 8; filaments 0.1 mm long, lengthening after anthesis; anthers linear-oblong, 1.8-2.4 × 0.4 mm wide, antisepalous anthers c. 0.3 mm longer than antipetalous ones, non-apiculate. Styles 4, clavate, c. 0.2 mm long, vestigial. Ovary ± cubiform, 0.7 mm long, 0.6 mm wide, lobed opposite petals, non-functional. Petals and stamens oflowermost whorl of male flowers sometimes smaller than in upper whorls. Female flowers. Sepals 4, deltoid, 0.2 mm long, 0.2 mm wide, minutely serrate, vestigial. Petals 4, 0.5 mm long, vestigial. Stamens 0. Styles 4, clavate, 0.5 mm long, stigmas fimbriate, cream. Ovary ± cubiform, 1.0 mm long, 0.8 mm wide, 4-lobed opposite petals. Fruit reddish-purple, ± cubiform, 1.3-1.4(-1 .5) × 1.4-1.5 mm wide, styles persistent and erect, fruit prominently 4-lobed opposite styles, splitting at maturity into 4 mericarps. Mericarps cylindrical, 1.4 mm long, 0.8 mm diam., smooth and rounded on dorsal surface, sometimes with a faint dorsal line, planar on faces where joined to other mericarps.

Flower Colours

Cream,White

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 = 42

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

Where To Buy

Not commercially available.

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 13 May 2014