What does it look like?
Rough horsetail is an upright, summer‑green perennial that grows up to two metres tall and spreads through deep underground stems, forming dense colonies. An extensive network of underground stems (rhizomes) allows it to spread easily.
The stems are hollow, ridged, and feel hard and rough to the touch. They are jointed and can break easily at these points. Leaves are reduced to small, toothed sheaths that wrap around each joint, with a distinctive black ring or collar at the base.
Rough horsetail does not produce flowers or seeds. Instead, it reproduces by spores, which are produced in cone‑like structures on fertile stems. Because of its unusual appearance, it’s often compared to a strange asparagus spear and is sometimes grown as an ornamental plant.
Why is it a problem?
Rough horsetail is capable of forming pure stands in wide range of damp habitats, preventing the seedlings of native species from establishing. It spreads rapidly, resprouting from underground stems, and displacing desirable plant species once established in an area. It’s resistant to most herbicides and its underground rhizomes make it hard to control. It blocks and alters watercourses, causing flooding.
Rough horsetail prefers moist areas like gravel areas and pond/lake margins. Once it’s well established, it will adapt to a wide range of conditions. It can even be found growing through the cracks in concrete.
Control methods
Physical control
Dig out and burn all parts and contaminated soil. If manually removing the plant, be aware that the rhizomes can grow to 1m deep.
Herbicide control
As this plant mainly grows around water, care is required if you are using chemical control methods.
Spray (summer) with metsulfuron-methyl 600g/kg (5g/10L) or a product containing 100g picloram+300g triclopyr/L (25ml/10L). Add penetrant.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
More information
Native to North America, Europe, and northern Asia it’s actually part of a “living fossil” species which has grown for over 100 million years. It was introduced to New Zealand as an ornamental plant, especially for aquatic habitats.
Related links
Management Programme
National Pest Plant Accord
All plants on MPI's National Pest Plant Accord (NPPA) are unwanted organisms under the Biosecurity Act 1993 whose formal or casual trade contributes significantly to their spread.
Plants on the Accord cannot legally be propagated, distributed, or sold in New Zealand. If allowed to spread further, these pest plants could seriously damage our economy and environment.
Unwanted Organism
An unwanted organism is any organism that's capable of causing harm to natural or physical resources (like forests and waterways) or human health. A number of introduced pests in New Zealand are classed as unwanted.
More informationTaxonomies
FamilyEquisetaceae
TypePlants
GroupPerennial
HabitatLand
Management ProgrammeNational Pest Plant AccordUnwanted Organism
