Karroo thorn

Alert

Be on the lookout for Karroo thorn.

Report sightings

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

Description

  • 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.

Habitat

  • 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.

Distribution

  • Detections recorded on the Darling Downs and in Rockhampton.
  • 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

Impacts

Environmental

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

Economic

  • 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.

Control

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