Prota 16: Fibres/Plantes à fibres
Hooker’s Icon. Pl. 14: t. 1359 (1881).
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Origin and geographic distribution
Brachystegia longifolia is distributed in DR Congo, Tanzania, Malawi, Zambia, Angola and Mozambique.
The inner bark is used for making rope; it was formerly used for making bark cloth. In Zambia the bark and root are used for making fishing nets and baskets.
The tree is an important local source of fuelwood, and is used for making charcoal. The wood is also used for tool handles, temporary construction, fences and mine props. The tree provides fodder for cattle. It is also a source of feed for bees and edible caterpillars, and it provides shade.
In traditional medicine a decoction of the root is taken for the treatment of bile problems and stomach-ache. The bark is steeped in cold water for half an hour and the liquid is drunk in case of worms or other stomach problems, or the bark is steeped overnight and used in an enema. The leaves are pounded in water to make a bath for sick children.
The wood is moderately heavy, with a density of about 710 kg/m³ at 12% moisture content. It is moderately hard. At 12% moisture content, the modulus of rupture is 86 N/mm², modulus of elasticity 9900 N/mm², compression parallel to grain 48 N/mm², shear 13.7 N/mm² radial and 12.6 N/mm² tangential, and cleavage 9.7 N/mm radial and 9.5 N/mm tangential. The wood is susceptible to borers and not very durable. In papermaking trials the wood yielded pulp of poor quality.
Browse from coppice regrowth in Zambia contained per 100 g dry matter: crude protein 12.1 g, P 190 mg, Ca 480 mg and Mg 270 mg. The bark contains 7–9% tannin.
Deciduous, small to medium-sized tree up to 30 m tall, sometimes a shrub; bole straight, often with conspicuous rounded bosses; outer bark deeply or shallowly fissured longitudinally, often coarsely reticulate, flaking in thick irregular scales, dark grey or dark brown; crown spreading, rounded to obconical or flat; main branches suberect to spreading. Leaves alternate, 7–25 cm long, paripinnately compound with (5–)6–18 pairs of leaflets, the pairs very variable in spacing; stipules intrapetiolar, shortly connate at base, filiform, linear, lanceolate-falcate to subfoliaceous, 10–35 mm × 1–5 mm, caducous, with reniform to subcircular auricles 1–17 mm × 0.5–9 mm, auricles caducous independently of stipules; petiole 1–5 cm long, pulvinate; rachis deeply canaliculate with raised and winged margins; leaflets extremely variable in shape, size and indumentum, narrowly triangular, ovate to oblong, sometimes falcate, the middle leaflet or the one next to the proximal one the largest, the proximal leaflet pair 1–5 cm × 1–2 cm, the middle leaflet pair 2.5–8 cm × 1–3 cm, base obliquely rounded, cordate or truncate, apex acute or rounded, thin, leathery, glabrous or pubescent. Inflorescence a terminal or axillary panicle up to 10 cm long, glabrous or with dark or rusty hairs; peduncle usually slender and terete, rarely grooved; bracts ovate to oblong, 2.5–4 mm × 1.5–3 mm, acute at the apex. Flowers bisexual, greenish white; pedicel up to 2.5 mm long; bracteoles 2, valvate, obovate or orbicular, 6–8 mm × 3–4 mm; sepals 5, oblong, obovate, lanceolate or imbricate, 2–4 mm × 0.5–5 mm, the proximal and lateral sepals often fused; petals 0–4, linear to spatulate, 2.5–3 mm × 0.5 mm; stamens 10, united for 1 mm at the base, filaments 10–20 mm long; ovary superior, style up to 12 mm long. Fruit an oblong to obovate pod 7–20 cm × 2.5–5 cm, rounded to obtuse at the apex with a 4–8 mm long beak, flattened, woody, smooth or scurfy, pale to dark brown, 2–6-seeded, explosively dehiscent. Seeds oblong to ovoid, 12–15 mm × 10–15 mm, flattened, chestnut-brown.
In Zambia Brachystegia longifolia flowers mainly in September–December and the fruits ripen in June–September.
Brachystegia is a taxonomically difficult genus comprising about 30 species, distributed in tropical Africa. Brachystegia taxifolia Harms is a shrub or small tree up to 12(–16) m tall, distributed in DR Congo, Tanzania, Malawi and Zambia. Its bark is used as tying material, for instance in hut construction. The wood is not durable, but it makes good charcoal. The tree is also a source of feed for bees and edible caterpillars.
Brachystegia longifolia occurs at 200–2100 m altitude in deciduous woodland. It is locally dominant or co-dominant.
The plant can be propagated with seedlings or wildlings. It can be coppiced, pollarded and lopped. For the production of bark cloth in Malawi, the bark was stripped off, soaked and beaten out. Blankets were made by sewing together several strips.
Genetic resources and breeding
As Brachystegia longifolia is fairly widely distributed and locally dominant, it seems not threatened with genetic erosion.
Brachystegia longifolia is a local source of fibre, but detailed information on the properties of the fibre is not available, making it difficult to assess the prospects of the species as a fibre plant. The tree yields a range of other products, of which fuelwood is probably the most important.
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Correct citation of this article:
Brink, M., 2010. Brachystegia longifolia Benth. In: Brink, M. & Achigan-Dako, E.G. (Editors). Prota 16: Fibres/Plantes à fibres. [CD-Rom]. PROTA, Wageningen, Netherlands.