Pest control hub
What does it look like?
Submerged, bottom-rooting perennial growing to 9m, with slender, brittle and branched stems (1 mm diameter). Translucent, dark green leaves (6-12 x 2 mm) in whorls of 3-8, have distinctly toothed margins, and the plant also produces small tubers and turions (hibernating buds). Only male flowers are present in New Zealand, so no seed is set.
Why is it a problem?
Eradication of this plant is at a national level. A progress report in 2016 declared that no plants had been found at the only known infestations in Hawkes Bay for more the 5 years so it is well on the way to being eradicated from New Zealand.