​​Geraldton Carnation Weed​ infestation © Morgan Lythe

​​Geraldton Carnation Weed​

Euphorbia terracina

Quick facts

Status
Permitted s11
Life Cycle
Perennial
Growth Form
Herb
Origin
Southern Europe and western Asia
Flowers
Yellow/green
Dispersal
Birds, other animals
Toxicity
Skin irritation, temporary vision loss

Names

Other Common Names: Terracina Spurge, Geraldton Carnation Spurge

Form and function

Plants typically grow between 20 and 80 cm tall, although they may occasionally reach 1 m. Fire usually kills mature plants, however some plants can resprout after burning. Fire may also trigger mass germination of soil-stored seed, creating favourable conditions for the establishment and spread of new populations. Seeds can persist in the soil seedbank for 3 to 5 years. The plant exudes a caustic milky sap when cut or injured. 

Flowers

  • Flowers are grouped in small cup-shaped structures called cyathia.
  • Yellow/green in colour.
  • Each cyathium contains several tiny male flowers and one female flower in the centre.
  • Cyathia occur near the tips of branches and in the upper leaf axils.
  • Paired yellow-green, egg-shaped floral leaves are present around the cyathia.

Geraldton Carnation Weed flower © Arthur Chapman

Leaves

  • Leaves are arranged alternately along the stems, without stalks.
  • Stem leaves are narrow and linear (up to 40 mm long and up to 8 mm wide).
  • Upper leaves on fertile branches ovate to triangular (up to 55 mm long and up to 30 mm wide).
  • Leaf margins can be finely serrated.
  • Leaves are bright green in colour.

Geraldton Carnation Weed leaves © bennybotany85

Fruits

  • Smooth, three‑lobed capsule (up to 5 mm long and up to 5 mm wide).
  • Rounded to slightly flattened shape.
  • Capsule hangs downward at maturity.
  • Each capsule contains three seeds.
  • Seeds are smooth and egg‑shaped and grey, mottled brown or black in colour.
  • Seeds about 2 mm long.

Geraldton Carnation Weed © Alan Dandie

Roots

  • Robust vertical taproot.
  • Horizontal lateral roots present at several levels.
  • Woody base capable of producing new stems after damage.

Geraldton Carnation Weed © Bradlp10

Habitat

Grows in the warm temperate regions with winter-dominated rainfall. It grows on well-drained sandy soils and shallow soils that have high calcium carbonate content. It is predominantly found in coastal heath, Tuart woodland communities and disturbed sites such as roadsides and degraded bushland.

May be confused with...

Similar non-native species: Similar to the caper spurge (Euphorbia lathyris) but can be distinguished by its single main stem compared to the carnation weed that has several stems near the base of the plant. Similar to the sun spurge (Euphorbia helioscopia) which can be distinguished by its egg-shaped leaves compared to the carnation weeds longer narrow leaves. Similar to the sea spurge (Euphorbia paralias) which can be distinguished by its smaller, narrower and overlapping leaves compared to the carnation weeds slightly larger, less narrow and alternately arranged leaves. Similar to the petty spurge (Euphorbia peplus) which can be distinguished by its single main stem and egg-shaped leave.

How does it spread?

​​Local dispersal by fruit opening explosively, further dispersal by birds (particularly feral doves), ants, movement of limestone soils brought into bushland for paths and by machinery​.

Why is it a weed?

  • Forms dense infestations that outcompete most other plant species, including in native bushland, reducing biodiversity.
  • Toxic to humans and livestock and may cause hydrogen cyanide poisoning in grazing animals.
  • The milky sap is highly caustic and can cause severe skin irritation, painful inflammation, eye injury and temporary blindness.

History

First naturalised in the coastal dunes near Adelaide, South Australia in the early 1900’s and became well-established in Geraldton, Western Australia where it was classified as common by 1914.

How to control

Arum Lily

Physical

Arum Lily

Chemical

With any control of Geraldton carnation weed, wear appropriate personal protective equipment to avoid contact with plant sap.

Physical

For scattered individual plants or small infestations, hand pulling is an effective method, particularly if the plants are fruiting, as seed can be prevented from spreading. Plants as young as three weeks must be completely removed with their roots or they will regrow and go on to produce the same amount of seed as an ungrubbed plant. However, hand removal and disturbance to the topsoil can stimulate the germination of the soil seedbank.  

​An alternative would be using mechanical removal methods by cutting plants at ground level at the base by hand or with a brush cutter, although this is only effective after plants have seeded. Any material, particularly any containing flowers or fruit, should be disposed off-site otherwise plants left on the soil surface can go on to produce seed. 

 

Chemical

Small infestations

For actively growing plants in small infestations, apply a foliar spray containing 20 mL glyphosate (450 g/L), 0.2 g metsulfuron-methyl (600 g/kg) and 25 mL penetrant in 10 L of water.

Large infestations

For large infestations with young plants, apply a foliar spray containing 0.1 g metsulfuron-methyl (600 g/kg) and 30 mL penetrant in 15 L of water. This treatment is reasonably effective but may not provide complete control of mature plants.

Where large infestations contain both adult and juvenile plants, apply a foliar spray containing 1.25 g triasulfuron (750 g/kg) and 1 mL penetrant in 1 L of water. This treatment is expected to have minimal impact on surrounding native vegetation.

Further
reading

Minor use permit
external link Permit PER96570 for glyphosate
external link Permit PER96598 for metsulfuron

Weed Distribution Map

LSID number: [2918542] | full LSID: [https://id.biodiversity.org.au/node/apni/2918542] | field_lsid: [] | taxon: [​​Euphorbia terracina]

ALA Reference

References

  • Atlas of Living Australia. (n.d.) Euphorbia terracina L. Atlas of Living Australia.
  • Bettink, K. (2009, December) Geraldton carnation weed Euphorbia terracina Draft strategic plan for the Swan NRM Region . Department of Environment and Conservation .
  • Brown, K., & Brooks, K. J. (2003) Bushland weeds: a practical guide to their management With case studies from the Swan Coastal Plain and beyond. Environmental Weeds Action Network
  • Moore, J., & Wheeler, J. (2008) Southern weeds and their control. Department of Agriculture and Food, Western Australia.
  • Stajsic, V. (2018b, June 6). Euphorbia terracina L. Terracina Spurge. VicFlora Flora of Victoria.
  • Weeds Australia. (2019, March) False Caper, Geraldton Carnation Weed, Terracina Spurge, Geraldton Carnation Spurge. Weeds Australia.
  • Weeds of Australia. (n.d.) Euphorbia terracina L. Weeds of Australia.
  • Western Australian Herbarium (1998–) Florabase—the Western Australian flora. Department of Biodiversity, Conservation and Attractions.

Life Cycle

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Notes
Germination
Active growth
Flowering
Fruiting
Dormant
Regularly or most commonly
Occasionally, given suitable conditions

Management

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Notes
Physical
Chemical
Optimal
Potentially, but conditionally dependent
Last updated: October 2026