Introduced from South Africa as a garden plant, boneseed, or salt bush, is now spreading rapidly throughout the country, competing with native species. It thrives in poor soil and dry coastal areas and spreads alarmingly fast because birds eat and carry the seeds far and wide. Although it burns easily, it comes back even stronger after a fire.
The shrub grows up to 3m, has dull-green toothed leaves covered in a cottony down, and its daisy-like flowers come in clusters from late winter until late summer. Each plant produces up to 50,000 hardy seeds a year.
It’s included in Canterbury’s Regional Pest Management Strategy for Biodiversity Pests and the objective is the removal of all existing plants from outside the Port Hills and a 20 percent reduction of infested areas within the Port Hills over the next 10 years.
Christchurch City Council and local residents have been working diligently on controlling boneseed at Southshore Spit for over 10 years and have reduced its infestation markedly.
This hard work requires maintenance, including pulling out seedlings by hand to ensure the area does not revert back to “Boneseed Spit”.