Prota 7(1): Timbers/Bois d’œuvre 1
Fl. trop. Afr. 2: 359 (1871).
Mimosaceae (Leguminosae - Mimosoideae)
Poison-pod albizia, large-leaved false thorn (En). Mchani ndovu, mkenge, mnduruasi, mduruasi (Sw).
Origin and geographic distribution
Albizia versicolor is widespread from DR Congo east to Kenya, and south to Namibia and South Africa.
The wood is locally used for small boats, tool handles, mortars and other kitchen implements, containers, casks and musical instruments. It is suitable for light construction, light flooring, joinery, furniture, cabinet work, decorative work, veneer, plywood, draining boards, hardboard and particle board. It is also used as firewood (although it may spark badly) and for charcoal production. The bark has been used for tanning and the flowers serve as a source of nectar for honey bees. The inner bark is used for making rope. Roots boiled with water can be used as a substitute for soap. Albizia versicolor is planted as an ornamental shade tree.
Root and bark decoctions are used as an anthelmintic and purgative, and to treat swollen glands and venereal diseases. Dried and powdered roots are taken or sniffed to treat headache and sinusitis, and a root maceration is taken against gonorrhoea. A bark decoction is used to treat anaemia, and it is applied externally to treat ophthalmia and skin rash. A bark maceration is taken against cough, and bark powder is sniffed for the same purpose.
The heartwood is pale to purplish brown, often darker striped, sometimes almost black; it is distinctly demarcated from the white sapwood, which is up to 5 cm wide. The grain is wavy or interlocked, texture coarse.
The wood is moderately heavy, with a density of 560–770 kg/m³ at 12% moisture content. It dries slowly with little degrade, but surface checking occurs in excessively cross-grained pieces. The rates of shrinkage are low: from green to 12% moisture content 1.1% radial and 1.8% tangential, and from green to oven dry 1.8% radial and 3.0% tangential. Once dry, it is stable in service.
At 12% moisture content, the modulus of rupture is 52–57 N/mm², modulus of elasticity 6500–7700 N/mm², compression parallel to grain 32–41 N/mm², shear 10–12 N/mm², cleavage 54 N/mm radial and 69 N/mm tangential and Janka side hardness 4630 N.
The wood saws and works well, but the surfaces of quarter-sawn boards may pick up. The use of a filler is needed to obtain a smooth finish. The wood does not hold nails well, and pre-boring is required. The jointing and gluing properties are good, but steam bending properties are usually poor. The wood dust may cause serious irritation to nose and throat.
The wood is moderately durable, but liable to attacks by pinhole borers and marine borers. Reports on its resistance to termites vary from susceptible to resistant. The heartwood is resistant to impregnation by preservatives, the sapwood is permeable.
Pods and seeds are poisonous to livestock; young pods are most toxic, but livestock is more often poisoned as a result of eating fallen pods. Cattle, sheep and goats may develop hypersensitivity, intermittent convulsions and high temperature, and may die from heart failure, but most animals recover without treatment. The disease is called albiziosis, and is caused by the presence of methylpyridoxine. Treatment of poisoned sheep with pyridoxine hydrochloride resulted in recovery. Kaempferol glycosides and several triterpenes (lupeol, lupenone, betulinic acid and acacic acid lactone) have been isolated from the bark of Albizia versicolor.
Small to medium-sized deciduous tree up to 20 m tall; bole usually short and branchless for up to 5 m but sometimes up to 12 m, straight and cylindrical, up to 60(–150) cm in diameter; bark surface greyish brown, rough and fissured; crown flattened, open, with spreading branches; young twigs rusty brown hairy. Leaves alternate, bipinnately compound with 1–4(–5) pairs of pinnae; stipules awl-shaped, caducous; petiole 5–7 cm long, grooved above, near the base of upper side with a sessile gland, rachis 8–20 cm long, rusty brown hairy; leaflets in 3–6 pairs per pinna, almost sessile, obliquely broadly obovate to almost orbicular, up to 6.5 cm × 5 cm, rounded to slightly notched but mucronate at apex, leathery, densely yellowish or reddish brown hairy below. Inflorescence an axillary head on 3–6 cm long peduncle. Flowers bisexual, regular, 5-merous, white to greenish yellow; pedicel up to 2 mm long; calyx 4.5–8 mm long, with long tube toothed at apex, rusty brown pubescent outside; corolla 8–12 mm long, rusty brown pubescent outside; stamens numerous, 2.5–5.5 cm long, united at base, filaments reddish; ovary superior, gradually tapering into a long and slender style. Fruit an oblong, flat pod 10–30 cm × 3–6.5 cm, almost glabrous, indistinctly transversely veined, yellowish brown to reddish brown when ripe, opening with 2 papery valves, c. 6-seeded. Seeds flattened ellipsoid, 9–13 mm long.
In southern Africa Albizia versicolor trees usually flower in August–December and fruits are ripe in December–March. The pod valves with seeds still attached are spread by wind. The growth rate of trees is moderate. The roots develop nodules containing nitrogen-fixing bacteria.
Albizia comprises about 120 species and occurs throughout the tropics. Approximately 35 species are found in continental Africa and about 30 in Madagascar. It is characterized by the head-like inflorescence, with 1–2 central flowers modified, functionally male and having a larger, nectar-producing staminal tube. Molecular analyses showed that Albizia is heterogeneous, and a revision is needed.
Albizia versicolor occurs in deciduous woodland and wooded grassland up to 1700 m altitude. It prefers well-drained soils with a high water table.
Seeds should be collected before the pods dehisce, which makes collecting difficult. Seeds on the ground are often infested by insects. One kg contains 6000–8000 seeds. Seed germination is usually good, up to 90%, and is completed in 30 days. Fresh seeds do not require any treatment, but stored seeds should be soaked in water for 6 hours before sowing. They can be stored for long periods when kept under dry and insect-free conditions. Seeds are preferably sown in seedling trays filled with a mixture of river sand and compost (4:1). Propagation by cuttings and root suckers has been successful. Planted trees can be managed by lopping and pollarding. Harvested logs are often of poor quality, being short and irregular or with heart rot in larger sizes.
Genetic resources and breeding
There are no indications that Albizia versicolor is threatened by genetic erosion, although it is locally uncommon within its wide area of distribution, e.g. in Uganda.
Albizia versicolor has good prospects as an auxiliary tree in agroforestry systems, improving the soil with its nitrogen-fixing root nodules, providing mulch with its leaf litter, reducing erosion with its large rooting system, and protecting crops from too much sun. This, together with other local uses, especially as timber tree and medicinal plant, makes it a multipurpose tree worthy of cultivation on a wider scale. However, its toxic fruit components warrant some caution in areas subject to heavy grazing. It is also recommended as an ornamental tree for large gardens and parks.
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Correct citation of this article:
Lemmens, R.H.M.J., 2007. Albizia versicolor Welw. ex Oliv. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
obtained from Zimbabweflora
obtained from Zimbabweflora
wood in transverse section
wood in tangential section