An invasive weed that could threaten native wetland plants has been discovered in New Zealand.
Great Willowherb - otherwise known by its scientific name, Epilobium hirsutum - has been detected in five areas in Canterbury, The Ministry for Primary Industries has confirmed.
It is not yet clear how the weed got into the country.
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The native North African and European weed has been discovered in and around the lake at the Pegasus township, north of Christchurch, and near the Kate Valley landfill - about 40km north of Lake Pegasus.
Biosecurity New Zealand response team manager John Brightwell says it has been identified at five sites.
"We're in the early stages of determining the severity of this incursion," he explained.
"Once we've determined this, we'll work closely with Environment Canterbury and the Department of Conservation to develop an appropriate response," Mr Brightwell says.
Because of its aggressive growth there are concerns it could crowd native wetland plants by forming dense stands impeding water flow in waterways and wetlands.
Currently there is no risk to freshwater fish or agriculture.
Cantabrians are being urged to look out for the weed, and to report it to Biosecurity New Zealand's pest and diseases hotline if they think they've spotted it anywhere on public or private property.