It might look like an attractive green plant with pretty yellow flowers but it is an invasive weed which the Department of Conservation (DOC) and Marlborough District Council have united to destroy.
DOC ranger Phil Clerke and council bio-security officer Ben Minehan and their teams have just completed the third year of trying to rid the Marlborough Sounds and Marlborough region of boneseed.
The weed can quickly transform open landscapes into impenetrable shrub-land, impeding human access and excluding native vegetation.
Mr Minehan said it was a particular threat in coastal areas. Also, known as saltbush, bitou bush, or Higgin's curse, boneseed could be identified by its bright yellow daisy-like flowers, Mr Minehan said.
"It is an invasive plant because it grows very quickly, displacing most other vegetation."
The weed, which originates from the Cape region of South Africa, has been discovered in Marlborough at Rarangi, Karaka Point, Ocean Bay, Ruakaka Bay, Te Punga Bay, Opua Bay, Te Awaiti, and Glasgow Island.
Mr Minehan said about 16,000 plants were discovered and destroyed in the first year of the programme. During flowering each year staff return to destroy any seedlings in the same areas before they get a chance to seed and germinate. "The programme is having an amazing impact. It's hard to put it into figures at this stage but we are noticing a major change."
He said boneseed was one of New Zealand's most serious environmental weeds. It is also recognised as a weed of national significance in Australia.
Infestations are known throughout the country including Canterbury's Port Hills, coastal areas of Wellington, Auckland, and Northland, and on the hills around port Nelson.
Birds disperse its seeds after eating the fruit of the boneseed plant but humans are also guilty of spreading it. "People think it's a nice plant with pretty flowers so they take plants from their home gardens and plant them at their holiday homes in the Sounds."