Prota 7(1): Timbers/Bois d’œuvre 1
Kew Bull. 1955(2): 181 (1955).
Mimosaceae (Leguminosae - Mimosoideae)
Piptadenia paucijuga Harms (1914).
Mkunguni, mpilipili, mbonta, mche (Sw).
Origin and geographic distribution
Newtonia paucijuga is restricted to coastal regions of Kenya and Tanzania.
The wood is suitable for construction, flooring, joinery, furniture, interior trim, toys, novelties, boxes, crates, turnery, veneer, plywood, hardboard, particle board and pulpwood. It is traditionally used for the construction of dhows and canoes.
The heartwood is pinkish brown to reddish brown, often with darker stripes or ripple marks, distinctly demarcated from the cream-coloured, 2.5–5 cm thick sapwood. The grain is wavy or interlocked, texture fine to moderately coarse, even or slightly uneven.
The wood is moderately heavy. At 12% moisture content, the density is 640–770 kg/m³. The wood usually air dries satisfactorily, but some end splitting and distortion may occur. The rates of shrinkage are moderately low, from green to oven dry 2.5% radial and 4.5% tangential. Boards 2.5–5 cm thick take about 6 months to air dry from green to 12% moisture content.
At 12% moisture content, the modulus of rupture is 94–98 N/mm², modulus of elasticity 11,400–12,200 N/mm², compression parallel to grain 54–57 N/mm², shear 16–20 N/mm², cleavage 54 N/mm radial and 72 N/mm tangential, and Janka side hardness 6140 N.
The wood saws and works well, both with hand and machine tools. Planing is difficult because of the presence of interlocked grain. Pre-boring is recommended before nailing and screwing, but the wood holds nails well. Painting and varnishing do not cause problems. The wood is suitable for veneer production, but drying of the veneer may cause considerable splitting.
The wood is moderately durable. It showed moderate resistance to termite attack, but is susceptible to powder-post beetle and marine borer attacks. In tests it showed excellent resistance against white and brown rot fungi. The heartwood is rather resistant to impregnation by preservatives.
Medium-sized to fairly large tree up to 35 m tall; bole usually straight and cylindrical, branchless for up to 12 m, up to 100 cm in diameter, at base usually without buttresses; bark surface smooth, pale grey to greyish brown, inner bark yellowish pink, with orange translucent exudate; young twigs densely reddish brown short-hairy. Leaves alternate, bipinnately compound with 1–2 pairs of opposite pinnae; stipules absent or indistinct; petiole and rachis together up to 4 cm long, with a short gland between each pinna pair; leaflets opposite, (1–)2–3 pairs per pinna, with a short gland between each leaflet pair, sessile, obovate to elliptical, 1–7 cm × 0.5–4 cm, cuneate at base, rounded or notched at apex, glabrous. Inflorescence an axillary or terminal spike-like false raceme up to 10 cm long, often many together at ends of twigs, hairy, densely flowered. Flowers bisexual, regular, 5-merous, nearly sessile; calyx with c. 1 mm long tube, slightly toothed, hairy outside; petals free, lanceolate, 2–2.5 mm long, hairy outside in upper part, whitish; stamens 10, free, anthers without gland at apex; ovary superior, hairy, style slender, curved. Fruit a flattened linear pod 23–60 cm × 2–3 cm, shortly stiped at base, reddish brown, transversely veined, dehiscent at one side. Seeds oblong, flat, 7–9 cm long including the papery wing surrounding the seed, brown, attached near one end.
Newtonia comprises about 15 species and is restricted to Africa. It seems related to Fillaeopsis from central Africa and Lemurodendron from Madagascar.
Newtonia hildebrandtii (Vatke) Torre is also found in Kenya and Tanzania, usually in riverine forest and dry bushland with high groundwater tables up to 1100 m altitude, but it is much more widespread than Newtonia paucijuga, south to eastern South Africa. It is a medium-sized tree up to 25 m tall; its leaves have 4–7 pairs of pinnae, each with 6–19 pairs of leaflets. The reddish brown and moderately heavy wood is used for house construction, poles, implements and carvings, and it is considered an excellent firewood and suitable for making high-quality charcoal. A root decoction is used as an anthelmintic. Bark extracts of Newtonia hildebrandtii showed antimicrobial activity against a range of pathogenic bacteria and fungi.
Newtonia erlangeri (Harms) Brenan is a small to medium-sized tree up to 20 m tall, with 1–4 pairs of pinnae per leaf, each with 5–12 pairs of leaflets. It occurs in coastal regions of Somalia, Kenya and northern Tanzania, in riverine forest and dry bushland with high groundwater tables. Its wood is used for house building and a bark decoction is taken for treatment of tympanites. The foliage serves as forage for livestock.
Newtonia paucijuga occurs in secondary forest, lowland moist evergreen forest and riverine forest, less often in dry evergreen forest, up to 500 m altitude.
Although Newtonia paucijuga is locally fairly common, e.g. in the Shimba Hills in Kenya, it has a limited area of distribution. It occurs mainly in pockets of moist coastal forest, a type of habitat that is severely fragmented. It is classified as vulnerable in the IUCN Red list.
The wood properties of Newtonia paucijuga are quite good, and there is certainly interest on the international timber market. However, the declining and fragmented populations are a serious drawback for commercialization of this species, and attention should be focused primarily on its conservation.
• 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.
• Brenan, J.P.M., 1959. Leguminosae subfamily Mimosoideae. In: Hubbard, C.E. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 173 pp.
• Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
• Ishengoma, R.C., Gillah, P.R., Amartey, S.A. & Kitojo, D.H., 2004. Physical, mechanical and natural decay resistance properties of lesser known and lesser utilized Diospyros mespiliformis, Tyrachylobium verrucosum and Newtonia paucijuga timber species from Tanzania. Holz als Roh- und Werkstoff 62(5): 387–389.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Lewis, G., Schrire, B., MacKinder, B. & Lock, M., 2005. Legumes of the world. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 577 pp.
• Lovett, J. & Clarke, G.P., 1998. Newtonia paucijuga. In: IUCN. 2007 Red list of threatened species. [Internet] http://www.iucnredlist.org Accessed March 2008.
• Maundu, P. & Tengnäs, B. (Editors), 2005. Useful trees and shrubs for Kenya. World Agroforestry Centre - East and Central Africa Regional Programme (ICRAF-ECA), Technical Handbook 35, Nairobi, Kenya. 484 pp.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Palmer, E. & Pitman, N., 1972–1974. Trees of southern Africa, covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland. 3 volumes. Balkema, Cape Town, South Africa. 2235 pp.
• Tanzania Forest Division, 1966. Timbers of Tanganyika: Newtonia paucijuga (mdadalika). Tanzania Forest Division, Utilisation Section , Moshi, Tanzania. 4 pp.
• Villiers, J.-F., 1990. Contribution à l’étude du genre Newtonia Baillon (Leguminosae - Mimosoideae) en Afrique. Bulletin du Jardin botanique national de Belgique 60: 119–138.
Correct citation of this article:
Lemmens, R.H.M.J., 2008. Newtonia paucijuga (Harms) Brenan. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.