Quick Facts

Quick facts

• Original from southern Europe, north Africa and western Asia, Sea Spurge (Euphorbia paralias) is a semi-succulent plant producing short-lived stems each year from a long-lived woody base.
• Its upright or semi-upright stems usually grows 20 to 70 cm tall and contain a toxic milky sap.
• Sea Spurge is a widespread weed of coastal habitats and offshore islands in the temperate regions of Australia, and is particularly common on coastal sand dunes.
• It quickly establishing large and dense infestations in open coastal communities, often becoming the dominant plant species.
• Change the structure and dynamics of sand dune systems, replacing native plant species, and decreasing the availability of beach nesting sites for shore birds and other animals.
• Produces and propagates by seeds, that can remain viable for up to two years in sea-water, allowing long distance dispersal. 
• Can be controlled by physical means and foliar herbicides.

What Does It Look Like?

What is it?

Sea Spurge (Euphorbia paralias) is a long-lived plant with upright or semi-upright stems. It usually grows 20 to 70 cm tall, but may occasionally reach up to 1 m in height. The stems die off after flowering and are replaced by new shoots from the woody base (or crown) of the plant. These hairless stems are often somewhat fleshy (2 to 5 cm thick), bluish-green in colour, and contain a milky white sap (latex). They usually divide into 3 to 5 small flowering branches near their tips, and these branches are often further divided. The crowded bluish-green leaves are stalkless and are borne in a densely overlapping arrangement along the stems. These relatively small leaves, 5 to 30 mm long and 2 to 15 mm wide and vary from being oblong (length a few times greater than width, with sides almost parallel and ends rounded), oval or ovate (shaped like a section through the long axis of an egg and attached by the wider end). However, the leaves on the flowering branches are usually somewhat circular or kidney-shaped and are paler green or yellowish in colour. Leaves are also relatively thick and hairless with entire (without teeth) margins, and the stems and leaves often turn reddish as they age (Navie & Adkins 2007).

The flowers are tiny, highly modified,  borne in small cup-shaped organs called cyathia (singular cyathium). Each cyathium contains several mostly inconspicuous male flowers and one central female flower with a conspicuous protruding ovary. These flowers (or cyathia) are clustered at the tips of the branches and are yellowish-green in colour. Each cyathium is borne on a separate stalk and the tiny cup-like structure is fringed with four orange crescent-shaped projections (glands) that resemble petals.

The fruit is a capsule and is most obvious part of the cyathium, a large green stalked ovary, which matures into the capsule 3 to 5 mm long and 4.5 to 6 mm wide containing three seeds. The smooth seeds, 2.5 to 3.5 mm long are egg-shaped or rounded and pale grey or whitish in colour (Navie & Adkins 2007).

For further information and assistance with identification of Sea Spurge contact the herbarium in your state or territory.

Flower colour

Green

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Sea Spurge is a weed of coastal habitats and offshore islands in the temperate regions of Australia. It occurs on free draining sandy soils on beaches, around estuaries, through dune fields, in coastal herbfields, grasslands, heaths and shrublands, and may also grow along rocky shorelines and in sand-filled cracks between rocks. However, it is most commonly found on coastal sand dunes (Blood 2001; Navie & Adkins 2007).

Are there similar species?

Sea Spurge is very similar to several other weedy spurges (Euphorbia spp.), including False Caper (Euphorbia terracina), Caper Spurge (Euphorbia lathyris), Sun Spurge (Euphorbia helioscopia) and Petty Spurge (Euphorbia peplus). But unlike many of these other species, Sea Spurge is usually found growing in sandy coastal sites (particularly on foredunes) and has somewhat fleshy leaves.

In addition, Caper Spurge, Sun Spurge and Petty Spurge all differ from Sea Spurge in being short-lived species with a single main stem. False Caper, which is the most similar species, differs in having its flowers (cyathia) borne in groups of two or three (Navie &Adkins 2007).

Why Is It A Weed?

What are its impacts?

Sea Spurge was included in the list of 71 species that were nominated by state and territory governments for assessment as Weeds of National Significance (WONS). Following an assessment process, Sea Spurge was not included as one of the 20 WONS. However, it remains a weed of potential national signficance.

Native ecosystems: Sea Spurge is regarded as a significant environmental weed throughout the coastal districts of southern Australia. It has successfully invaded many open coastal communities, quickly establishing large and dense infestations (Navie and Adkins 2007). Populations of this species may reach tens of thousands where beaches are free of other vegetation or have a low level of plant cover. It can also rapidly colonise eroded areas, such as blowouts (depressions in dunes caused by wind blowing the sand away), often becoming the dominant plant species.

Sea Spurge initially colonises the foredunes at the back of the beach. These infestations tend to stabilise the dunes, preventing natural sand movement inland, and creating a different dune structure to that created by native species (Rudman 2003). This can also decrease the availability of beach nesting sites for shore birds, and may be contributing to their decline in some areas. For example, the endangered Hooded Plover (Thinornis rubricollis) uses un-vegetated sand areas on beaches for nesting sites (Parks and Wildlife Service Tasmania 2003). If uncontrolled, Sea Spurge can then spread inland from these areas, displacing native vegetation and invading adjacent grassland communities. In New South Wales, Sea Spurge is thought to threaten the survival of endangered native coastal plants, such as Chamaesyce psammogeton (Navie & Adkins 2007).

Human impacts: Sea Spurge is poisonous to humans and the milky sap in its stems can be highly irritating when it comes into contact with the skin or when it is accidentally rubbed into the eyes (Parks and Wildlife Service Tasmania 2003).

How does it spread?

Sea Spurge reproduces and spreads by seed and has two main natural modes of dispersal. Short distance dispersal is when the mature fruit opens explosively and expel the seeds a few meters from the parent plant. Long-distance dispersal is via buoyant seeds in sea water. Seed can remain viable and float for several years and can be spread large distances by ocean currents (Heyligers 2002), sometimes washing up on far-away beaches. 

Humans can also assist the dispersal of seeds, by spreading by vehicles, ballast water or contaminated sand or soil. They can be moved about via beach grooming equipment, moving them to new areas in contaminated sand (Blood 2001).

What is its history in Australia?

The first herbarium collections of Sea Spurge in Australia were made in south-eastern South Australia in 1934 and western Australia in 1944 (AVH 2021). It is thought that seeds were accidentally introduced to these locations through shipping, possibly in ballast water carried by grain ketches. 

Sea Spurge first appeared in  Victoria in the early 1957 and in  southern New South Wales in the mid 1980s 

In Tasmania the earliest collection of this species was made in 1980 on the north-east coast (Heyligers 2002).

How To Manage It?

Best practice management

Check with your local council or state/territory weed management agency about its requirements for Sea Spurge control. Killing plants is quite easy but it can be hard to achieve long-term control of sea spurge because seeds can spread to new or previously controlled areas via the ocean. Success is more likely in areas where infestations are new and the chance of re-infestation from local and floating seeds is low (NSW DPI 2019).

Non-chemical control: Small Sea Spurge infestations can be eradicated by physically removing the plants. Smaller plants can be hand-pulled easily, but large plants will need to be dug out. Protective clothing must be worn to protect skin and eyes from the toxic and highly irritative milky sap (Rudman 2003). Sea Spurge seedlings, which can occur in very large numbers, are best left to thin out naturally first and then pulled the following year prior to flowering. Follow-up will also be required to address subsequent seed germination or re-sprouting from broken taproots. Substantial declines in density of Sea Spurge can be achieved by this method, but it may take 4 to 5 years of concerted effort (Parks and Wildlife Service Tasmania 2003).

Chemical control: Herbicide treatments can also be used, and may be more appropriate where disturbance from hand-pulling is unacceptable or where large infestations are involved (Rudman 2003). Spot spraying is suitable method for larger infestations, and a number of herbicides have been successfully used to control sea spurge, including glyphosate and metsulfuron-methyl.

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Biological control: CSIRO (2021) reported that the foliar blight fungal pathogen Venturia paralias (previously referred to as Passalora euphorbiae),  causes severe disease of sea spurge in its European native range. Preliminary tests showed that this fungus is potentially highly specific and has thus great potential for the biocontrol of sea spurge in Australia. Comprehensive host-specificity testing have been performed in an Australian quarantine facility to assess any risks that the fungus could pose to non-target plant species. Results indicated that the fungus does not pose a threat to non-target species, and thus approval for its release in Australia was sought from the relevant authorities. The biocontrol agent was approved for release in November 2020 and research is underway to develop effective methods for production and field releases.

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

Mass germination of seeds occurs in spring and summer and young plants form a taproot very quickly (Blood 2001). Flowering usually occurs from spring through to early winter (September to June), but is more dependent on growing conditions than on the time of year. The stems die off after flowering and are replaced by new shoots from the root crown. The long-lived seeds can float in sea-water for several years and more than 50% can remain viable after floating in sea water for 2 years (Heyligers 2002).

Where Is It Found?

Which states and territories is it found?

NSW, SA, TAS, VIC, WA

What areas within states and territories is it found?

Sea Spurge is widely naturalised in the coastal districts of central and southern New South Wales, Victoria, Tasmania, South Australia and southern and south-western Western Australia. It has also recently become naturalised on Lord Howe Island (Navie & Adkins 2007).

First recorded in South Australia in 1934 on the Yorke Penensula (AVH 2021), Sea Spurge has spread remarkably quickly and is now found along most of the South Australian coast, including the offshore islands. It is particularly common on the western coast of the Yorke Peninsula and is also a common coastal weed in the Gulf of St Vincent area near Adelaide. 

First recorded in Western Australia in 1944, common on the western and southern coast. 

It has also spread rapidly since its appearance in southern New South Wales and Victoria, and by 2001 it had increased its range from these few isolated occurrences to be present along the coastline from Jervis Bay in the north to Marlo in the south, a distance of about 550 km (Heyligers 2002). 

In Tasmania, Sea Spurge is now the dominant coastal weed of the northern and western coastlines of Tasmania and large populations are also present on the Bass Strait islands (Rudman 2003).

Where does it originate?

Sea Spurge is native to western and southern Europe (Ireland, the UK, Belgium, the Netherlands, France, Portugal, Spain, Albania, Bulgaria, Greece, Italy, Romania, Yugoslavia and Ukraine), the Canary Islands, northern Africa (Algeria, Egypt, Libya, Morocco, Mauritania and Tunisia) and western Asia (Cyprus, Egypt, Israel, Jordan, Lebanon, Syria and Georgia) (Heyligers 2002; GRIN 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

Not declared in any Australian states or territories

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Euphorbia paralias

Other scientific names (synonyms)?

Does it have other known common name(s)?

Spurge