Karoo and Giraffe Thorn
Vachellia karroo (Hayne) Banfi & Galasso declared as Acacia karroo Hayne and Vachellia erioloba (E. Mey.) P.J.H. Hurter declared as Acacia erioloba E. Mey. Karoo thorn
Karoo thorn and giraffe thorn are declared under the Catchment and Land Protection Act (1994) as State prohibited weeds. These trees are native to southern Africa. Karoo thorn has been introduced into Victoria through plantings in botanic gardens, zoos and public parks, however giraffe thorn has not been recorded in Australia. These trees have the potential to invade large areas of regional Victoria if introduced and not removed.
The white spines of Karoo thorn may be up to 25 cm long and occur in pairs.
What are State prohibited weeds?
State prohibited weeds either do not occur in Victoria, or are present and can reasonably be expected to be eradicated. State prohibited weeds are the highest category of noxious weeds under the Catchment and Land Protection Act (1994). The Department of Economic Development, Jobs, Transport and Resources (DEDJTR) is responsible for the eradication of State prohibited weeds. The Victorian Government is committed to preventing the introduction of high-risk weeds into Victoria, to protect our environment and social values.
Why are they a problem?
Karoo thorn is one of the most widespread trees in southern Africa and is a weed in Europe, South America and South Africa. It has the potential to invade southern Australia, particularly in open grasslands and rangelands in the south-east. The spines injure grazing animals, and make thickets impenetrable. Giraffe thorn has been assessed as potentially highly invasive in Australia. Climate predictions indicate that it could occupy large areas of inland and northern Australia.
How to identify these plants
Karoo and giraffe thorn plants can grow as either shrubs or trees: Karoo thorn grows 4-25 m tall and giraffe thorn grows 2-16 m tall. Both have green fern-like leaves, and yellow ball-shaped flowers which appear in spring to summer.
Karoo thorn seed pods are smooth, sickle-shaped, growing to 16 cm long and split open exposing ripe seeds. Giraffe thorn seed pods are half-moon shaped growing to 13 cm long, they are covered in velvety grey hairs and do not open.
The white paired spines of the Karoo thorn can grow up to 25 cm. Giraffe thorn spines are also paired and white but only grow up to 6 cm long and often have a swollen base.
What should you do if you find these plants?
If you think you have seen a Karoo thorn or giraffe thorn, please contact DEDJTR by telephoning 136 186.
Please do not attempt to control or dispose of this weed yourself.