Vascular – Native
Herbs - Dicotyledons other than Composites
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.
2n = 42
Current conservation status
The threat classification status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – a suggested threat classification status has not been assessed by the NZTCS panel.
2017 | Not Threatened
Previous conservation statuses
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Endemic. New Zealand: North, South and Chatham Islands
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland).
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
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.
Easily grown from fresh seed and rooted pieces. An excellent plant for pond, slow flowing stream or fish tank.
myriophyllum: Many leaves
Where To Buy
Not commercially available.
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.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Myriophyllum triphyllum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/myriophyllum-triphyllum/ (Date website was queried)