General Info – summary

This deciduous, drought, frost resistant Tree is up to 14m high.  It has short, curved, paired spines.  Big bipinnate Leaves have many small-paired leaflets.  Stipules lack spines.  Yellowish, regular, bisexual Flowers are in spikes.  The male free, initially white, filaments are exerted.  The female has a superior ovary with a belatedly extended style.  Fruit is a flattish dehiscent pod with round compressed seeds.

Description

Senegalia caffra

Previous names: Acacia caffra, Mimosa caffra, Acacia fallax, Acacia multijuga.

SA Tree No. 162.

Common names: (Afr) Amaquasdoornboom, Gewone Haakdoring, Hakiesdoring, Katdoring, Wag-‘n-bietjie, Wag-‘n-bietjie-doring, Water Thorn.  (Eng) Cat Thorn, Cat-thorn, Common Hookthorn, Common Hook-thorn, Hook-thorn, White Thorn.  (isiXhosa) Umnyamanzi, Umthole, Umtholo.  (isiZulu) Umtholo, Umthole.  (Northern Sotho) Moroba Diepe, Moroba-diêpe, Mositsane, Motholo, Radiepane.  (Setswana) Morutlhare.  (siSwati) umTfololwane, Lugagane, Umgamba, isinga.  (Tshivenda) Muvunda-mbado (the axe breaker).  (Xitsonga) Mbvhinya-xihloka.

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 Tree genera on this website include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cordyla, Cyclopia, Dichrostachys, Erythrina, Erythrophleum, Faidherbia, Indigofera, Mundulea, Peltophorum, Philenoptera, Piliostigma, Schotia and Xanthocercis.  The Fabaceae are recognisable by their fruit and by their pinnately compound Leaves.  Leaves may also be simple – even bilobed 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 1 locule containing 1 or more ovules.  The Stigma and Style are simple.  The single carpel develops into the Fruit, which is usually a pod.  The mature pods may dehisce or break into segments.  Seeds vary.

Name derivation. Species of the genus Vachellia and Senegalia were considered members of the genus Acacia until 2005.  New Names.  The genus Vachellia was named after George H. Vachell (1789 – 1839), chaplain and plant collector in China.  Here the inflorescence is capitate (head like) and spinescent stipules are present.  Plants in the genus Senegalia – (from Senegal) usually do not have spinescent stipules and the inflorescence is usually a spike.  caffra – from the eastern Cape.

Conservation: National Status: L C. (Least Concern).  Assessment: 2005 (W. Foden and L. Potter).

Tree

This impressive, upright, often flat-topped Tree (photo 674) is up to 23m high.  The relatively straight Trunk may reach a diameter of 0,6m.  The thick, rough, pale yellowish Bark changes to grey as it ages (photo 639).  It tends to be flaky or peels off in thick corky flakes and loose strips.  The whitish Branches have a covering of white, silver hairs – hence the common name “white thorn”.  This feature is most noticeable when the tree is leafless (photo 674).  The branches that occur rather high up have strong widely spaced, brown or black, paired, hooked thorns that are up to 1,5cm long and occur just below branch nodes (photo 108).  Single, persistent down pointing distinctly cushioned spines may also appear on the trunk (photo 496).  Lenticels (usually raised corky oval or elongated areas on the plant that allow the uncontrolled interchange of gases with the environment) are present on young branches.

Leaves

On this deciduous tree, the new Leaves are bright green and may be the first tree with new leaves in early spring.  The large drooping leaves (photo 890) are up to 23cm long and bipinnate (Compound: twice pinnate.  The central leaf axis or rachis has lateral Pinnae “branches” not leaflets and the Pinnules (leaflets) are on these “side branches”).  The Rachis (an extension of the petiole of a compound leaf that eventually bears the leaflets) is grooved above.  Each leaf has up to 26 pairs of lateral pinnae – each of which has up to 50 pairs (usually less) of very small, smooth, feathery and light green Leaflets (photos 890 & 100).  The leaflets are up to 8 x 2mm, asymmetric (photo 14) and may be hairy.  Here the veins are prominent on the lower surface of each leaflet (photo 14).  The Petiole (leaf stalk) is up to 3cm long, is grooved above, and may have prickles below.  The upper surface has a small Gland more than halfway up (photo 510).  Additional glands are usually found on the groove between 4 pairs of pinnae (photo 100).  Petiolules (bases of leaflets – photo 14) are very short.  Small Stipules (basal appendages of the petiole are not spinescent and fall early (photo 523 under Tree).

Flowers

The creamy to yellowish white Flowers occur in hanging clustered Spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched axis opening in succession towards the apex – photo 853).  Each spike is up to 13cm long and spikes emerge from leaf axils.  A Peduncle (stalk of flower cluster) attaches to base of each spike (photo 215).  Each flower is bisexual and actinomorphic (Regular, symmetrical.  Flowers are vertically divisible into similar halves by more than 1 plane passing through the axis).  They have a strong fragrance and are one of the first trees to flower in spring.  The Calyx is up to 3mm long and the initially greenish–yellow buds turn red (photo 853).  The yellowish Corolla is up to 3,5mm long and has 4 united Petals.  The many relatively long and distinctly exserted (sticking out; projecting beyond) Stamens have long free Filaments (photo 859) and are initially straight and clearly white.  They provide the white or cream colour to the young flowers (photo 215).  The filaments become yellowish and crinkled with age (photo 853 LHS).  There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma).  Here the superior Ovary has a single locule.  A small filiform (thread or filament like) Style is present.  Once the pollen has been shed, the style elongates and extends the single terminal Stigma beyond the now older and somewhat curled up, yellowish stamen filaments (photo 853 – esp. lower LHS).  The stigma now becomes receptive to pollen.  This delayed development helps to enable cross-pollination.  (Sep-Dec).

Fruit

The long, velvety, pale or dark brown Fruit is a flattish, dehiscent Pod.  It is up to 15 x 1,5cm and may be straight or curved (photo 540 & 749).  The round Seeds are compressed, and the pod is somewhat constricted between seeds (photo 749).  Parasitic insects may damage the seeds (photo 579).  Dehisced pods, still with visible seeds, may remain on the tree for some time (photo 540).  (Dec-Mar+).

Distribution & Ecology

Only subsp. campylacantha occurs in Africa.  These Trees grow in deep, relatively moist soils or alluvial soils near rivers, in thorn veld / subtropical bushveld and open parkland.  They can survive both dry weather and low temperatures.  This tree is found in Limpopo and Mpumalanga e.g. in Northern Kruger National Park – Punda Maria and Pafuri areas.  Beyond South Africa, it occurs in central and northern Mozambique and as far north as Gambia and Ethiopia.  The tree Roots have compounds that repel animals e.g. rats, snakes and crocodiles.  The leaves allow sunlight penetration and thus grass can grow underneath the trees.  Larvae of the scarlet Butterfly Axiocerses tjoane feed on the Leaves.  These butterflies are located in eastern and southern Africa.  Larvae of the Crawshay’s Hairtail Butterfly (Anthene crawshayi) feed on young terminal Shoots.  The Speckled Emperor Moth (Gynanisa maia) has larvae that feed on the leaves of this plant and on leaves of Mopane and Combretum.  These moths occur from South Africa to eastern Africa.  Another associated moth is the African wild silk moth (Gonometa postica).  This silk producing moth has larvae that feed on the leaves on this and other members of the Fabaceae (the legume family).

Ethnobotany

The strong Wood is termite resistant.  Heartwood is dark brown but the coarse-grained wood is not much used.  The Bark can be used for tanning leather.  The Gum (a water-soluble sugary polysaccharide that is exuded to seal wounds and prevent infection by bacteria and fungi, and helps prevent trees from freezing) can be used as glue and in confectionary.  The African wild silk moth Gonometa postica has an edible pupa.  Silk can be harvested from their tough cocoons.  When filled with things like small shells, these cocoons can be used as ankle rattles.  This fast-growing tree is easily raised from Seed but needs to be protected from frost for the first year or two.  This attractive tree is not a tree for small gardens.  It has invasive roots and should be kept away from buildings.  Fresh roots have a strong odour.  They are used in local medicine and for magical purposes.  The wood is also used in local medicine.

References

Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.

Burrows, J.E., Burrows, S.M., Lotter, M.C. & Schmidt, E.  Trees and Shrubs Mozambique.  Publishing Print Matters (Pty) Ltd.  Noordhoek, Cape Town.

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.

Foden, W. & Potter, L. 2005. Senegalia caffra (Thunb.) P.J.H.Hurter & Mabb. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2023/12/16.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants. The Macmillan Company, New York. Tenth Printing 1965.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa. Balkema, Amsterdam, Cape Town.

Ross, J. H. A conspectus of the African Acacia Species. 1979. Botanical Research Institute.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park. Jacana, Johannesburg.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa. Struik, Cape Town.

 

https://en.wikipedia.org/wiki/Senegalia_caffra

http://plantzafrica.com/plantab/acaciacaffra.htm

https://en.wikipedia.org/wiki/Senegalia_caffra

http://posa.sanbi.org/flora/browse.php?src=SP