Karroo thorn


Have you seen Karroo thorn?

Be on the lookout for Karroo thorn and report it to Biosecurity Queensland. Early detection and reporting are the key elements in preventing Karroo thorn from becoming a major problem in Queensland.

You must take reasonable action to minimise the risk of spreading Karroo thorn to ensure the situation isn't worsened.

You must report all sightings to Biosecurity Queensland within 24 hours.

Call us on 13 25 23.

Native to southern Africa, Karroo thorn is a fast-growing shrub or tree. It could become a serious invasive plant in Queensland, with the potential to reduce agricultural productivity by suppressing the growth of grasses.

Scientific name

Vachellia karroo

Other names

  • Sweet-thorn, cockspur thorn, Cape gum, mimosa thorn

Similar species


  • Shrub or tree up to 12m tall.
  • Thorns are white, paired, up to 10cm long.
  • Flowers are yellow, ball-shaped, in clusters of 4–6, 1–1.5cm in diameter.
  • Bark is rough, red-brown to black.
  • Leaves are light-green, fern-like, up to 12cm long, 5cm wide.
  • Leaflets are 3.5–8mm by 1–3mm.
  • Seed pods are sickle-shaped, woody, slightly constricted between seeds, up to 16cm long, 1cm wide.


  • Prefers range of soil types, generally in areas of rangelands in subcoastal, semi-arid and arid southern Queensland.
  • Drought-tolerant due to extensive root system.


  • Two recorded infestations on the Darling Downs.
  • Visit Weeds Australia and click on the distribution tab to access the distribution map.

Life cycle

  • Reproduces by seed; large trees produce up to 19,000 seeds per year.
  • Seeds can lie in soil for 7 years and still germinate.
  • Flowering occurs mostly during summer.

Affected animals

  • Livestock
  • Cattle



  • Invades large areas, particularly where land has been overgrazed.
  • Resists fire and is well-suited to rangelands and open grasslands.


  • Reduces agricultural productivity by suppressing grass growth.
  • Prevents stock movement and can restrict watering.

How it is spread

  • Seeds spread by wind and water or in droppings of animals.


Legal requirements

  • Karroo thorn is a prohibited invasive plant under the Biosecurity Act 2014.
  • You must not keep, move, give away, sell or release into the environment. Penalties may apply.
  • You must not take any action reasonably likely to exacerbate the biosecurity threat posed by Karroo thorn.
  • You must take any action that is reasonably likely to minimise the biosecurity threat posed by Karroo thorn.
  • You must report all sightings to Biosecurity Queensland within 24 hours.

Further information