Nymphoides montana
Common name
marshwort, entire marshwort
Synonyms
Nymphoides geminata (R. Br.) Kuntze
Family
Menyanthaceae
Flora category
Vascular – Exotic
Structural class
Herbs - Dicotyledons other than Composites
Conservation status
Not applicable
Brief description
Floating leaved aquatic plant with ‘lily’ shaped leaves and yellow flowers, that can develop dense stands in still and slow flowing waters.
Distribution
Locally naturalised, Auckland to Canterbury, eradicated from most known sites.
Habitat
Still and slow flowing water bodies.
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).
Detailed description
Underwater stem creeping or floating near the surface, with leaves and roots at each note. The leaves are heart-shaped and up to 10 cm across, bright green on upperside and often pinkish on the underside. The main vein is indistinct. Flowers are bright yellow 2.5-3.5cm wide, with 5 petals that have fringed marginal wings. Flowers found above the water surface on long stalks that grow in pairs from short leafless side stems.
Similar taxa
Fringed water lily (Nymphoides peltata), water poppy (Hydrocleys nymphoides), water lily (Nymphaea spp.), and yellow water lily (Nuphar lutea). Fringed water lily has leaves with scalloped margins, whereas marshwort has entire leaf margins. Yellow water lily has very thick spongy stolons (up to 10 cm) and much larger floating leaves (up to 40 cm long and 30 cm wide). Water lily has a larger leaf with a distinct main vein. Water poppy has an ovate leaf with an inflated mid-vein on the underside.
Flowering
November, December, January, February, March, April.
Flower colours
Yellow
Fruiting
Not known to fruit in New Zealand
Life cycle
Perennial. Vegetative spread by creeping stem growth and fragmentation. Deliberate plantings.
Year naturalised
1985
Origin
Australia
Reason for introduction
Ornamental pond plant
Control techniques
Can be controlled manually, mechanically or herbicidally depending on situation.
Etymology
montana: From the Latin mons ‘mountain’, meaning growing on mountains
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Aston, H.I. 2009: Notes on Australian taxa of Nymphoides (Menyanthaceae): typification and nomenclature. Muelleria 27: 119-126.
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Aston, H (1977). Aquatic plants of Australia. Melbourne University Press, 367pp.
Clayton, J.S.; Tanner, C.C. (1985). Nymphoides geminata (R. Sr.) Kuntze in New Zealand. NZJ Botany 23: 187-190.