What does it look like?
Sea spurge is a long-lived herbaceous coastal plant native to Africa, temperate Asia, and many parts of Europe. It’s invasive in Australia. The plant is fleshy and glaucous (bluish grey/green) with stalks that turn reddish brown with age and grow up to 70cm tall. The stems contain a milky sap that is toxic to people and animals. Leaves are obovate-oblong at the base to ovate at the top of the stems and are approximately 5-20mm in length and 2-15mm in width. The leaves are crowded and overlap along stems that branch from a woody base, dividing into 3–5 flowering branches. It produces clusters of cup-shaped flower heads on distinct stalks.
The flowers are cyathia (“false” flowers) consisting of a single female flower surrounded by male flowers (reduced to stamens) and four crescent-shaped glands that contain nectar to attract pollinators. Each flower is enclosed by a pair of bracts (modified leaves or scales) measuring approximately 1.5 mm long. The plant produces capsule-like fruits containing three large seeds that are buoyant and can be dispersed over vast distances by ocean currents. Sea spurge grows from deep taproots. It was first recorded in the Waikato region in 2012, then in Taranaki and Manawatu in 2019, and was found in Kahurangi National Park on the West Coast in 2020.
Why is it a problem?
Sea spurge (Euphorbia paralias) is a potentially serious coastal environmental weed that poses a serious threat to the ecological and physical structure of our sand dunes. It’s native to western and southern Europe and is now well established along the Australian coastline. Seeds can survive up to six years in sea water and up to about 15 years in ideal conditions on land.
The species forms dense infestations in coastal, open sand areas and around beach debris, from the high-water flotsam line into the dunes. It’s most likely to be found on the west coast of the north and south islands of New Zealand due to seed transferral from Australia, but there is also the possibility of currents moving seeds to northeastern beaches. The New Zealand climate is similar to that of the species native habitat and is not thought to be a barrier to establishment.
If it establishes here, sea spurge could overrun many native dune species including spinifex, pingao and a number of sea grasses. It could also threaten the habitats of native birds such as dotterel and terns.
Control methods
Known sites are regularly inspected to remove sea spurge plants before they set seed.
Do not disturb plants as sea spurge is very similar to the threatened native species - Euphorbia glauca and the New Zealand linen flax, Linum monogynum. Moving plants could spread seeds, and breaking stems releases the milky sap which is toxic and can cause skin and eye irritations. Ideally, take a photo and note the location as accurately as possible – GPS coordinates are ideal.
More information
If you think you have found sea spurge, please contact Biosecurity New Zealand at 0800 80 99 66. Do not disturb the plant in any way.
Related links
Sea Spurge a serious threat to New Zealand's beaches fact sheet
Management Programme
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.
