Alligator weed has been discovered in Taranaki.
Work is now under way to establish how far the invasive pest plant has spread.
Taranaki Regional Council environment services manager Steve Ellis says the identification of the aquatic weed in a lagoon near Waitara is disappointing but was perhaps inevitable, given it is widespread in neighbouring regions.
"Obviously we didn't want it in Taranaki, but the fact it's been found is good news. We are hopeful we have identified it relatively early, allowing us a window of opportunity in which to contain its spread."
Alligator weed (Alternanthera philoxeroides) is a low-growing non-woody perennial plant that is considered one of the world's worst weeds.