This endangered Tree may reach 15m high. The grey bark becomes fissured. Leaves are bipinnate with wavy leaflets. Regular Flowers are have exserted stamens. Fruit is a slender pod. Seeds are flat and hard.
RSA Tree No. 156.
Common names: Zulu False-thorn, Zulu Albizia
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 include Acacia (Vauchellia, Senegalia), Albizia, Bauhinia, Bolusanthus, Burkea, Calpurnia, Colophospermum, Cyclopia, Dichrostachys, Erythrina, Erythrophleum, Faidherbia, Indigofera, Mundulea, Peltophorum, Philenoptera, Schotia and Xanthocercis. 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. This pod dehisces on both sides and may break into segments. Seeds vary.
Name derivation: Albizia: Albizia: Named after Filiopo degli Albizzi who introduced a species to Europe in 1749. suluensis from Zululand (Kwa-Zulu Natal). There are 11 indigenous species of the genus Albizia in southern Africa.
Conservation Status: Endangered 2014 (Raimondo et al.). This species occurs in areas where employment rate is low and where wood is used for building, fuel and for medicinal use. The area is also being cleared for subsistence farming and is becoming home to the alien plant Chromolaena odorata (paraffin weed – smell of leaves) which is native to North and South America. This invasive and flammable weed affects species diversity. The population trend of Albizia suluensis is decreasing.
The Tree is 10 to 15m high and has thickish branches and a rounded or flat spreading crown. The tree has a straight trunk with grey, smooth or fissured Bark. It is unarmed (no thorns or spines). Branchlets are blunt-tipped and thick. They are hairy when young.
This deciduous tree has Leaves that are bipinnate (twice compound: the rachis has lateral “branches” not leaflets and the leaflets are on these side pinnae “branches”). Leaves are up to 15cm long and as long as wide. There are up to 5 pairs of pinnae each bearing 4-9 pairs of leaflets. There is a small gland at the base of the lowest pair of pinnae. Leaflets are dark blue-green above and lighter below and may be nearly square or obovate or oval and about 2,8 x 1,5cm. They may be hairy. The Apex is rounded or square and may show a long gradual taper. The Base is asymmetric. The Margin is distinctly wavy – unusual in Albizia leaflets. The grooved upper surface of the Petiole (leaf stalk) is up to 7cm long. The Stipules (basal appendages of the petiole) are not spinescent and usually shed early. Short Petiolules (leaflet stalks) are also present and often sparsely pubescent.
The creamy-white or pinkish Flowers form a half-spherical head. Flowers open from golden velvety buds. Golden velvety hairs are present. Flowers are actinomorphic (Regular, symmetrical. The Perianth, the calyx and corolla, is divisible into 3 or more identical sectors). There are golden velvety hairs on the Calyx, which is up to 4mm long. It has a tube ending in short lobes. The Corolla has a funnel shaped tube that is at least as long as the calyx. It usually has 4 lobes with rusty coloured hairs. The many exserted Stamens are up to 1,6cm long and are united at their base. They are whitish and fluffy giving the flowers their colour. The Anthers are peltate (shield-shaped) with the thecae (pollen sacs) opening outwards. The pedicels (stalks of a single flower) are up to 4cm long. (Sep-Jan).
The Fruit is a light brown slender dehiscent Pod up to 21 x 2,6cm. The pods have a slightly thickened margin and seed position is marked by small swellings. Seeds are round flat and hard.
Distribution & Ecology
The Tree is endemic (Endemism is the ecological state of a species being unique to a defined geographic location) in northern KwaZulu-Natal near the towns of Hlabisa and Hluhluwe. Trees occur in forests, forest margins, savanna (is a rolling grassland scattered with shrubs and isolated trees, which can be found between a tropical rainforest and desert biome), on steep slopes and on riverbanks. The tree is also located in woodland in altitudes ranging from 270-1 400m and may occur in groups. Long tailed Samango monkeys eat the Leaves.
These Trees grow best in full sunlight. The hard and durable Wood can be used to make good furniture. Sawdust causes sneezing. This is a good ornamental tree. The Bark crushed with water foams and is used locally as an enema. Like most “Acacia” trees, the seeds germinate better if they are first soaked in boiling water and left over night. It takes up to 10 days for the Seeds to germinate.
Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.
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.
Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town.