Tree may reach 9m high. Fissured flaking bark. Leaves are bipinnate and paired. Spinescent stipules. Yellowish ball shaped Flowers have exserted stamens. Fruit vertical, upright straight swollen pods.
Acacia hebeclada, Vachellia hebeclada, Acacia stolonifera.
RSA Tree No. 170.2
Common names: Candle Thorn, Candle-pod Acacia, Blouhaakdoring.
Conservation Status: L C (Least Concern).
Family Fabaceae or Leguminosae (Pea, bean or legume family). After the Orchidaceae and the Asteraceae, the Fabaceae is the third largest Angiosperm (flowering plants) family with 700+ genera and close to 20 000 species. Local genera include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cyclopia, Erythrina, Erythrophleum, Faidherbia, Indigofera, Philenoptera and Schotia. The Fabaceae are recognisable by their fruit and by their pinnately compound Leaves. Leaves may also be simple and usually have stipules – some of which may be spinescent. Leaflets are usually entire. Flowers are bisexual and bracteate. Regular flowers usually have 4-5 sepals and the same number of petals. Irregular flowers have 4-5 sepals and 5 or less petals. Stamens have anthers that have 2 pollen sacs and there are usually at least twice the number of stamens as petals – often 10. The superior Ovary has one locule that may contain 1 or more ovules. The Stigma and Style are simple. The single carpel develops into the Fruit, which is usually a pod. The pod dehisces on both sides and may break into segments. Seeds vary.
This single stemmed Tree is medium sized – up to 9m high. In these trees, the Branches tend to droop. This plant may also be a shrub and form thickets up to about 1,5m high. The Crown is rounded or flattened and somewhat spreading. The mature tree is often wider than high. The branches occur low down and are nearly horizontal. Sub-surface branches can produce new growth away from the trunk (where the old name A. stolonifera originated). Young branches are stout, densely velvety and pale to dark. The flaking Bark is dark brown or grey to nearly black and almost vertically fissured.
This deciduous tree has up to 4 Leaves at a node. Leaves are bipinnate (compound: twice pinnate. The central axis or rachis has lateral “branches” not leaflets and the leaflets are on these “side branches”) Size and shape vary. There are 2-9 pairs of pinnae, each with up to 18 pairs of leaflets. Leaflets are small: up to 7 x 2mm and do not overlap. The Rachis (main axis bearing flowers or leaflets) is light green and hairy and possesses a gland between the top pairs of pinnae. The hairy Petiole (leaf stalk) is light green and usually less than 1cm long. Grooves may appear on top. A gland may be present on the upper surface (photo 45). The Stipules (basal appendage of the petiole) are spinescent and the paired Spines are usually short but may be up to 6cm long. They are sharp-tipped and may occur in opposite pairs. They may be brown, white or red-tipped. Spines can be straight or slightly curved downwards. They are pubescent (hairy) when young.
The bisexual Flowers are located at nodes and are actinomorphic (regular, symmetrical. The perianth, the calyx and corolla, are divisible into 2 or more identical sectors). The scented, spherical inflorescences occur in reduced spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched stalk). These spherical capitula (dense inflorescence with many flowers) are up to 17mm in diameter. There are up to 8 inflorescences at each node. Buds are green due to the colour of sepals. Peduncles (stalk of flower cluster or of a single flower when that flower is the remaining member of an inflorescence) are hairy and up to 20mm long. The small involucre (one or more whorls of small leaves or bracts standing underneath a flower or flower-cluster) occurs just above the base of the peduncles. The light green Calyx is up to 2,5mm long. The Corolla is also light green with darker green lobes and is up to 3,5mm long (photo 688). The Stamens, which distinctively protrude in large numbers have white, free Filaments and initially end with golden coloured anthers. This gives the inflorescence an overall creamy-white appearance. There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) and the superior Ovary has a single locule. A single, small, terminal Stigma and a filiform (thread or filament like) Style are present. Pollination agents include bees and flies. (Jul-Sep).
The distinctively straight, usually upright Fruit (photo 47) consists of swollen, sausage-shaped, dehiscent Pods, which arise at the nodes. They are only initially pulpy within. The top of the pod is rounded and the base tapers (photo 927). They remain on the tree after the seeds are shed. Pods develop on stout stalks and are initially green and hairy. They become hard, woody, up to 20 x 4,5cm and are covered with yellowish grey woolly hairs. Visible wrinkles and ridges spiral round the pod (photo 49). Each pod produces up to 14 reddish brown flattened Seeds that are up to 1,5 x 1,1cm. They are attached to a long funicle (the stalk by which the ovule is attached to the ovary wall or placenta: photo 365). (Oct-Apr).
Distribution & Ecology
The Tree is not endemic to South Africa. It is common in the dry areas away from the sea e.g. the Kalahari Gemsbok National Park where they may appear as a thicket. It also grows in calcrete (a hardened calcium rich layer in, or on, the soil) and on moist soils. This tree is cold and drought resistant. Found in Northern Cape, Mpumalanga, Gauteng, Free State (e.g. in their National Botanical Gardens) North West, and Limpopo. They also occur in Namibia, Botswana and Zambia.
This is an interesting, attractive and graceful small tree, which is difficult to cultivate. The Gum (a water-soluble sugary polysaccharide that is exuded to seal wounds and prevent infection by bacteria and fungi and prevents trees from freezing) is edible. Local people use Root extracts mixed with fat to dress hair. Roots can penetrate deeply for water. The Wood is strong and used for axe and hoe handles. Leaves may be poisonous due to the presence of prussic acid (flammable, colourless and extremely poisonous – formulae HCN cyanide – used in gold and silver mining). Seeds grow better when planted in mid-summer. File seeds before planting them in summer. They should germinate within 2 weeks. It is reported to be the host of the South African desert truffle species of Terfezia.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.
Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.
Ross, J. H. A conspectus of the African Acacia Species. 1979. Botanical Research Institute.
Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.