Fringed water lily
|Botanical Name||Nymphoides peltata|
IdentificationThis aquatic plant is a bottom rooted perennial which has long branched running stems (stolons) that extend up to one metre or more and lie just beneath the water surface. Each node on these running stems typically produces a plant as well as many thread-like roots. Each plant consists of several leaves arising on very slender stalks from the basal nodes. The floating leaves are almost circular (sometimes oval), up to 70mm in diameter and have very shallowly scalloped margins. The upper surfaces of the leaves are mid-green in colour, occasionally with some reddish-brown flecks while the under sides are a reddish-pink or reddish-purple colour. Golden flowers are borne above the water surface on long stalks. The flowers are normally 20 to 30mm in diameter and have five lobes, with each lobe having wings about 5mm broad and these are fringed on the outer margins. Flowering occurs from October to April. The flowers eventually form a flattened, beaked capsule approximately 20mm long containing numerous seeds. The seeds are flattish, oval and are bout 3.5mm long with hairy (ciliated) edges. These viable seeds are produced abundantly during summer and germinate readily the following spring.
HabitatsThis plant can grow in a wide range of habitats, from flowing water to swamps up to 2.5m deep, and can also grow on damp mud.
Impact to Biota and EcosystemsFringed water lily has the potential to become an unmanageable aquatic nuisance in suitable waterways. It can impede drainage, block access and be a nuisance to recreational activities, as well as displacing desirable native species.
Dispersal Routes, Vectors, Infestation SourcesThis plant spreads by seed as well as vegetatively. Localised spread occurs by the running stems which are able to extend up to several metres at a time. This plant also has the ability to grow roots from detached leaves thus providing an effective mechanism for vegetative dispersal from an established site. The seed hairs help it float and aid attachment to wildlife such as water fowl. Therefore seed is readily dispersed by water currents and birds such as ducks and swans, forming new infestations of this plant which can out-compete other water lilies and native species.
Smaller infestations are cleared by hand whilst larger sites are controlled by the laying of weedmat and the use of specialist herbicides. Plants removed by hand must be disposed of away from water courses.
Spraying with Glyphosate and Penetrant is effective on controlling emergent foliage. Repeated applications may be necessary.
Fringed water lily is a Natural Accord Pest Plant. All sightings of this plant should be reported to a Pest Plant Officer who will organise the clearance of the plant.
This plant originates from temperate parts of Europe and Asia and is a relatively recent arrival in NZ. It is occasionally cultivated in garden ponds and currently only one field site is known.
This plant is prohibited from propagation, sale and distribution within New Zealand!