Primrose willow is an emergent, aquatic perennial herb that forms dense mats.
Description
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Stems are creeping or floating, with upright flowering stems that root at the nodes.
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Leaves are 6cm long and alternate. The upper surface is glossy.
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Flowers are bright yellow, 2cm in diameter and appear between November-February.
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Fruit capsule is woody and 2.7cm long.
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Seeds and stem fragments are dispersed by water movement.
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Habitats include still and slow-moving water body margins, wetlands, damp ground, and pasture.
What you need to know
Primrose willow forms dense mats, displacing other vegetation, clogging waterways, impeding water flow and reducing dissolved oxygen levels. May negatively impact native fauna through habitat alteration.
Management approach
Primrose willow is declared an unwanted organism by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.
These species pose a high risk to our environment, economy, recreation, and cultural values.
Rules
Any species declared a pest, including unwanted organisms, cannot be sold or be in a place where plants are being sold. Pest plants cannot be propagated, bred, or multiplied, communicated, released, or cause to be released, or otherwise spread.
Control
Do not attempt to undertake control of primrose willow yourself. Report any sightings to us.
Primrose willow. Photo credit: Eugene Zelenko
Primrose willow. Photo credit: Nagarazoku
