Karoo and giraffe thorn

Karoo thorn and giraffe thorn — Vachellia karroo declared as Acacia karroo and Vachellia erioloba declared as Acacia erioloba — are State prohibited weeds.

Note: The scientific name for these species have been changed from Acacia species to Vachellia species. Acacia is the name listed in the legislation.

If you find karoo thorn or giraffe thorn

If you think you have seen karoo thorn or giraffe thorn, please contact us by:

Please do not attempt to treat or dispose of this weed yourself.

We will treat, remove and dispose of karoo thorn or giraffe thorn safely, at no cost to the land owner.

Why you must report these weeds

Karoo thorn is one of the most widespread trees in southern Africa and is a weed in:

  • Europe
  • South America
  • South Africa

It has the potential to invade large areas of southern Australia and especially regional Victoria, particularly in open grasslands and rangelands. The spines injure grazing animals and make impenetrable thickets.

Karoo thorn has been introduced into Victoria through plantings in botanic gardens, zoos and public parks.

Giraffe thorn has not been recorded in Australia.

Giraffe thorn has been assessed as potentially highly invasive in Australia. Climate predictions indicate that it could also occupy large areas of inland and northern Australia.

Identifying karoo thorn and giraffe thorn

Karoo thorn with large white thorns, flat fern-like leaves and yellow ball-shaped flowersKaroo thorn seed pods splitting openGiraffe thorn seed pods are smooth and fully enclosed

Karoo and giraffe thorn plants can grow as either shrubs or trees:

  • karoo thorn grows 4m to 25m tall
  • giraffe thorn grows 2m to 16m tall

Both have green fern-like leaves, and yellow ball-shaped flowers that appear in spring to summer.

Karoo thorn seed pods:

  • are smooth
  • are sickle-shaped
  • grow to 16cm long
  • split open exposing ripe seeds

Giraffe thorn seed pods:

  • are half-moon shaped
  • grow to 13cm long
  • are covered in velvety grey hairs
  • do not open

The white paired spines of the karoo thorn can grow up to 25cm. Giraffe thorn spines are also paired and white but only grow up to 6cm long and often have a swollen base.

Page last updated: 03 Feb 2021