Myriophyllum propinquum
Common names
common water milfoil
Biostatus
Native
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White, Yellow
Detailed description
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.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Not Threatened | Qualifiers: SO
Detailed taxonomy
Family
Haloragaceae
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Propagation technique
Easily grown from fresh seed and rooted pieces. An excellent plant for pond, slow flowing stream or fish tank.
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). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
Etymology
myriophyllum: Many leaves
propinquum: Very like the next species
NVS code
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.
MYRPRO
Chromosome number
2n = 14
Previous conservation statuses
2017 | Not Threatened | Qualifiers: SO
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Referencing and citations
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.
Attribution
Fact Sheet Prepared by P.J. de Lange (1 November 2009). Description based on Orchard (1979)
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Myriophyllum propinquum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/myriophyllum-propinquum/ (Date website was queried)