|Acacia karroo subsp. var.||Karroo thorn, Sweet thorn|
It is a shrub or small to medium-sized tree which grows to height of 12m. It is difficult to tell apart from Acacia nilotica subsp. adstringens without examining the seed pods. It is not listed as being a threatened species.
Common names in various languages include Karoo Thorn, Doringboom, Soetdoring, Cape Gum, Cassie, Piquants Blancs, Cassie Piquants Blancs, Cockspur Thorn, Deo-Babool, Doorn Boom, Kaludai, Kikar, Mormati, Pahari Kikar, umuNga and Udai Vel.
It is a shrub or small to medium-sized tree which grows to height of 12m. Acacia karroo has a rounded crown, branching fairly low down on the trunk. It is variable in shape and size, reaching a maximum of about 12m where there is good water. The bark is red on young branches, darkening and becoming rough with age. Sometimes an attractive reddish colour can be seen in the deep bark fissures The leaves are finely textured and dark green. The flowers appear in early summer in a mass of yellow pompons. The seed pods are flat and crescent shaped. They are green when young becoming brown and dry. The pods split open allowing the seeds to fall to the ground. The thorns are paired, greyish to white and are long and straight
It is a tree of open woodland and wooded grassland. It grows to its greatest size when rainfall of 800-900mm is received but can grow and even thrive in very dry conditions such as the Karoo region of western South Africa. The requirement here is for deep soils that allow its roots to spread. Everywhere in its range, however, the tree is easily recognised by its distinctive long white paired thorns and coffee coloured bark, both of which are very attractive. In the tropics it shows little variation but at the southern end of its range it becomes more variable in appearance.
Acacia karroo has a life span of 30-40 years and is an adaptable pioneer, able to establishing itself without shade, shelter or protection from grass fires. Once over a year old, seedlings can resprout after fire. Several fungi are associated with this tree and the crown of mature trees may be parasitized by various mistletoes, leading to the tree's decline. This tree has a long taproot which enables it to use water and nutrients from deep underground, this and its ability to fix nitrogen, lead to grasses and other plants thriving in its shade.
The tree has been noted to occur in the Torre del Mar area, near Malaga, Spain. Here it grows freely as a large shrub on waste ground. It has been used as hedging to keep out goats from vegetable plots. Flowers during July.
Pests and diseases
- ↑ Germplasm Resources Information Network: Acacia karroo
- ↑ Department of the Environment and Heritage and the CRC for Australian Weed Management, 2003
- ↑ 3.0 3.1 ILDIS LegumeWeb: Acacia karroo