Sweet thorn | |
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Not evaluated (IUCN 3.1)
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Scientific classification | |
Kingdom: | Plantae |
(unranked): | Angiosperms |
(unranked): | Eudicots |
(unranked): | Rosids |
Order: | Fabales |
Family: | Fabaceae |
Genus: | Vachellia |
Species: | V. karroo |
Binomial name | |
Vachellia karroo (Hayne) Banfi & Galasso |
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Native range of V. karroo | |
Synonyms | |
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Vachellia karroo, commonly known as the Sweet thorn, is a species of acacia, native to southern Africa from southern Angola east to Mozambique, and south to South Africa.
It is a shrub or small to medium-sized tree which grows to height of 12m. It is difficult to tell apart from Vachellia nilotica subsp. adstringens without examining the seed pods. It is not listed as being a threatened species. The Botanical Society of South Africa has accepted a name change to Vachellia karroo.
Common names in various languages include Acacia, Common acacia, 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. Vachellia 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 abundant yellow flowers appear in early summer, or after good rains. The seed pods are narrow, 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.
Vachellia 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.