Phragmites, common reed or cane grass
This pest is part of the National Interest Pest Response programme in New Zealand.
Report sightings to MPI’s exotic pest and disease hotline ph 0800 80 99 66.
Phragmites is a perennial grass that grows up to 6 m tall on water margins. It has bamboo-like stems which carry long, wide, flat leaves that taper to a point. The flower is showy and silky, purple or white, up to 40cm long, but doesn’t set seed in New Zealand. It is spread accidentally by root or rhizome (underground stems) fragments. It is similar to giant reed (Arundo donax), but phragmites is smaller and the stems are narrower in proportion to the leaves.
Frequently Asked Questions
What damage does it cause?
In its native habitat, phragmites usually grows in dense stands, excluding other plants. If allowed to become more widespread in New Zealand, it could crowd out native plants and reduce the numbers of insects and birds in wetland habitats.
Phragmites has dense growth which dies back each winter and can be a fire risk. It also blocks drainage systems causing flooding, and can invade low lying pasture as well as blocking access to waterways, restricting fishing and boating.
Phragmites is one of the nine pests that MPI, in partnership with regional councils and DOC, is working to eradicate as part of the National Interest Pest Response programme. It is an unwanted organism under the Biosecurity Act 1993 and is banned from sale, propagation and spread.
Where is it found?
Phragmites has only been found at a very limited number of sites in Canterbury, Hawke’s Bay and Tasman regions. This species was sold through the nursery trade for many years so there may still be plants tucked away in gardens or around ponds or waterways. Some of the plants sold through nurseries were variegated, and have green and white striped leaves. Phragmites prefers the margins of waterbodies, both freshwater and saline, but can also grow away from water.
What should I do if I find it?
You can help us get rid of phragmites. If you have seen it or suspect you have seen it, please contact MPI’s exotic pest and disease hotline ph 0800 80 99 66.
- University of Rhode Island Outreach Center
- Plant Conservation Alliance – Alien Plant Working Group
- MPI phragmites fact sheet (883 KB)
Page last updated: 28 April 2014