Species
Nymphoides geminata
Etymology
geminata: twinned
Common Name(s)
marshwort, entire marshwort
Authority
Nymphoides geminata (R. Br.) Kuntze
Family
Menyanthaceae
Brief Description
Floating leaved aquatic plant with 'lily' shaped leaves and yellow flowers, that can develop dense stands in still and slow flowing waters.
Flora Category
Vascular - Exotic
Structural Class
Dicotyledonous Herbs other than Composites
Distribution
Locally naturalised, Auckland to Canterbury, eradicated from most known sites.
Habitat
Still and slow flowing water bodies.
Features
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
Year Naturalised
1985
Origin
Australia
Reason for Introduction
Ornamental pond plant
Control Techniques
Can be controlled manually, mechanically or herbicidally depending on situation.
Life Cycle and Dispersal
Perennial. Vegetative spread by creeping stem growth and fragmentation. Deliberate plantings.
This page last updated on 30 Jul 2014