Senegalia ataxacatha (DC.) Kyalangaliwa & Boatwr.
Common names: Flamethorn (E), Vlamdoring / Rank wag-'n-bietjie (Afr), umThathawe (Z), Mologa (N.Sotho), Mogôkatau (Setsw), Muluwa (V), umNga (X).
SA Tree No: 160
The most striking feature of this plant are the deep red to purple-red pods which are held in conspicuous bunches and account for the common name "flame thorn".
It is a fairly untidy, many-stemmed shrub up to 3-5m in height, often scrambling. It may on occasion form a small tree with a stem diameter of up to 20-30cm in diameter. The bark is greyish, sometimes with a brownish tinge, and is fissured longitudinally, often with coarse flaking. Young stems are fairly smooth with longitudinal striations on which numerous unpaired, hooked prickles up to 8mm are borne. Small prickles are also found on the underside of the leaf axis.The large, fairly droopy, compound leaves are comprised of many tiny leaflets. The foliage is generally dark green and fairly dense, with the new growth often purple-tinged. The leaf stalk is hairy and bears a distinctive stalked gland.
The conspicuous creamy-yellow flowers are borne in clusters of caterpillar-like spikes at the ends of the branches. They are scented and make an attractive show anytime from mid summer to early autumn (January-April).
The deep red to purple-red pods are flat, semi-translucent, up to 85mm in length, tapering sharply at both ends. They are at their most attractive from April to July and dehiscent (splitting to release the seeds) from June to October. The pods contain usually 6-8 seeds which are olive-green to brown and flattened.
Distribution and habitat
The flame thorn is a common, widespread tree occurring in subtropical Africa from Senegal in the west to Sudan in the north-east, extending southwards into Namibia and South Africa it may be found through much of the former Transvaal province, KwaZulu-Natal and Swaziland. In drier areas it is usually confined to water courses and ravines, but in higher rainfall areas it may be encountered as a normal bush constituent or even forest margin situations. The flame thorn often forms impenetrable thickets - particularly in disturbed areas.
Derivation of name and historical aspects
This plant was previously called Acacia ataxacantha. The specific name ataxacantha = from the Greek "taxis" = arrangement and "akantha" = thorns, in reference to the many scattered prickles on the stems and shoots. Senegalia refers to the country in west Africa.
The leaves are the larval food for a number of butterfly species and birds such as Apalis, Crombecs and Woodhoopoes can often be seen collecting insects off the flowers, leaves and tree trunk.
As the stems are generally quite thin, the wood is mostly used for small implements and tools. The sapwood is wide and creamy while the heartwood is deep red brown. It is said to be resistant to decay owing to gum deposits. The wood can be split into paper-like strips without cracking and these strips are commonly used as weaving material for baskets. The roots are also used in basketry and have also been traditionally used to make long-stem tobacco pipes.
In parts of northern Zimbabwe, it was planted as an effective barrier along drainage lines during the liberation war, where it still persists.
It is used in traditional medicine to treat constipation and abdominal pains, and also to protect infants from witchcraft.
Growing Senegalia ataxacantha
The flame thorn is best grown from seed. The seeds should be soaked in hot water. Viability is highly variable and unpredicable. Seedlings should appear within 2 weeks of sowing. Growth rate after transplanting is initially slow and then increases. In the garden, it favours a well-watered position - however it does have fairly good drought-resisting properties. It should be protected from frost when young. As a hedging plant, it can form an impenetrable and attractive screen.
Although this tree usually has a rather untidy scrambling habit, the bright-coloured pods make it an attractive garden feature. It is, however, an excellent screening plant and is suitable for security hedging because of its thorniness. Specimens are planted on the lawns at the base of the waterfall in the Witwatersrand National Botanical Garden.
- Kyalangalilwa B, et al. 2013. Phylogenetic position and revised classification of acacia s.l.(Fabaceae Mimosoideae) in Africa, including new combinations of Vachellia and Senegalia. Botanical Journal of Linnean Society 172,500-523.
Witwatersrand National Botanical Garden
Plant Type: Shrub, Tree
SA Distribution: Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga
Soil type: Sandy, Clay, Loam
Flowering season: Late Summer, Autumn
Flower colour: Cream
Aspect: Full Sun
Gardening skill: Easy