Albizia aylmeri (PROTA)

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Plant Resources of Tropical Africa
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Albizia aylmeri Hutch. ex Broun & Massay


Protologue: Fl. Sudan: 175 (1929).
Family: Mimosaceae (Leguminosae - Mimosoideae)

Origin and geographic distribution

Albizia aylmeri is endemic to central Sudan.

Uses

The wood of Albizia aylmeri is used as timber and is suitable for construction, light flooring, interior trim, toys and novelties, turnery, veneer, plywood, hardboard and particle board.

Properties

The heartwood is reddish brown, often darker striped, and distinctly demarcated from the up to 5 cm wide, creamy to yellowish sapwood. The grain is often spiral, texture fine to coarse and even.

The wood is moderately heavy, with a density of about 740 kg/m³ at 12% moisture content. It should be dried slowly and carefully to avoid serious degrade. The rates of shrinkage are moderate: from green to oven dry 3.8% radial and 5.9% tangential. Once dry, the wood is stable in service.

At 12% moisture content, the modulus of rupture is 113 N/mm², modulus of elasticity 11,600 N/mm², compression parallel to grain 68.5 N/mm², shear 13.7 N/mm² radial and 11.8 N/mm² tangential, cleavage 7.3 N/mm radial and 7.4 N/mm radial, Brinell side hardness 28 N/mm² radial and 30 N/mm² tangential, and Brinell end hardness 57 N/mm².

The wood saws and works well, but causes rapid blunting of saw teeth and tool edges. It finishes to a smooth or rough surface depending on the wood texture. The nailing, screwing, gluing and staining properties are all good. The wood dust may cause irritation to nose and throat. The wood is moderately durable, being resistant to termite attack, but susceptible to marine borers. It is resistant to impregnation by preservatives.

Description

  • Medium-sized tree up to 25 m tall; bole up to 80 cm in diameter, often slightly twisted; bark surface brown, fissured.
  • Leaves alternate, bipinnately compound; leaflets in 5–8 pairs per pinna, obliquely broadly oblong to rhombic, 2.5–5 cm × 1–3 cm, rounded to obtuse at apex, whitish and pubescent below. Inflorescence an axillary head on c. 5 cm long peduncle.
  • Flowers bisexual, regular, 5-merous, sessile or with short, thick pedicel, greyish pubescent; stamens numerous, far exserted, united at base into a tube about as long as corolla; ovary superior, gradually tapering into a long, slender style.
  • Fruit an oblong, flat pod 17–20 cm × c. 3 cm, glabrous.

Other botanical information

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 of the genus is needed.

Ecology

Albizia aylmeri occurs in wooded savanna.

Management

Logs should be processed quickly after felling because the wood is susceptible to discoloration by blue-stain fungi.

Genetic resources

Albizia aylmeri has a small area of distribution and may be threatened by genetic erosion, but is too poorly known to establish its conservation status.

Prospects

Apart from sporadic tests of the wood, very little is known about Albizia aylmeri. There is no recent information on its uses and conservation needs.

Major references

  • Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
  • Gottwald, H. & Noack, D., 1966. Anatomische und physikalisch-technologische Untersuchungen an Holzarten der Republik Sudan. Mitteilungen der Bundesforschungsanstalt für Forst- und Holzwirtschaft No 64. Bundesforschungsanstalt für Forst- und Holzwirtschaft, Reinbek, Germany. 51 pp.
  • Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.

Other references

  • Andrews, F.W., 1952. The flowering plants of the Anglo-Egyptian Sudan, Volume 2. Buncle, Arbroath, United Kingdom. 485 pp.
  • Begemann, H.F., 1963-1969. Lexicon der Nutzhölzer: Vorkommen, Charakteristik und Verwendung der im Welthandel vorkommenden Nutzhölzer. 5 volumes. Holz-Verlag, Mering, Germany.
  • FAO, 2001. State of forest genetic resources in Sahelian and North-Sudanian Africa & regional action plan for their conservation and sustainable use. [Internet]. Forest Genetic Resources Working Papers No 2. Forest Resources Development Service, Forest Resources Division, FAO, Rome, Italy. http://www.fao.org/docrep/003/X6883E/x6883e00.htm. December 2007.

Author(s)

  • R.H.M.J. Lemmens, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Lemmens, R.H.M.J., 2007. Albizia aylmeri Hutch. ex Broun & Massey. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 11 April 2019.