The list of invasive weeds threatening New Zealand's native plants and ecosystems has expanded, with 112 new species added to the Department of Conservation's (DOC) Environmental Weeds List in 2024.

Among the new additions are species such as Chilean myrtle, Bangalow palm, and holly fern, all of which are increasing in both distribution and invasiveness.

Like many of New Zealand's environmental weeds, these species originally came from garden plants.

The updated list now includes 386 weeds, an 18% increase from the previous list in 2008, which only had 328 species.

This year's list also broadens its scope to include all environmental weeds, regardless of their location, unlike the previous list, which focused solely on those found on DOC-administered land.

DOC Science Advisor Dr. Kate McAlpine highlighted New Zealand’s vulnerability to invasive species, noting that the country hosts over 25,000 exotic plant species, a figure ten times greater than the number of native species.

She explained that many introduced plants quickly naturalise, often through wind or bird dispersal, or by people dumping garden waste near bush reserves.

The list also warns of 'sleeper' weeds like Himalayan wineberry and octopus tree, which are not yet established in the wild but have the potential to become fully invasive.

Dr. McAlpine added that climate change could exacerbate the issue, as warmer temperatures and extreme weather events may enable these species to thrive in new areas of New Zealand.

The DOC encourages the public to use the iNaturalist app to report weed sightings, helping environmental agencies track and manage the spread of these invasive species.

See the full list here.