Prota 7(1): Timbers/Bois d’œuvre 1
Bull. Misc. Inform. Kew 1908: 258 (1908).
Mimosaceae (Leguminosae - Mimosoideae)
2n = 24
Origin and geographic distribution
Xylia evansii occurs from Sierra Leone to Ghana.
The wood is used for local construction. The twigs are used as chewing sticks, and a decoction of leafy twigs is administered as a cholagogue and tonic. The leaves and ash from pods are used as a substitute for soap. Roasted seeds are reportedly edible. A vegetable salt has been obtained from wood ash by leaching.
The heartwood is reddish brown with darker streaks and distinctly demarcated from the pale yellow sapwood. The grain is interlocked; the texture fine. The wood is moderately heavy, with a density of about 770 kg/m³ at 12% moisture content, and hard. It dries quite fast and well. The recorded workability of the wood varies from fairly well to difficult. It is resistant against both fungi and insects.
Medium-sized to fairly large tree up to 35 m tall; bole often fluted and bent, up to 160 cm in diameter, with large, humped buttresses; bark brown, roughly scaly. Leaves alternate, clustered at the ends of twigs, bipinnately compound with a single pair of pinnae; stipules linear, persistent; petiole 1.5–5 cm long, shortly hairy, with large gland at apex on upper side; pinna axis 10–35 cm long; leaflets in 9–20 pairs per pinna, opposite, oblong-lanceolate to oblong-elliptical, up to 9 cm × 2 cm, rounded at base, acuminate at apex, shortly hairy below. Inflorescence an axillary head c. 2 cm in diameter, many-flowered; peduncle 3–8 cm long. Flowers bisexual, regular, 5-merous, small, sessile, hairy; calyx cylindrical, c. 3 mm long, shortly toothed; petals free, linear-oblong, c. 4 mm long, brownish yellow; stamens 10, free, c. 8 mm long, with glands at apex; ovary superior, c. 1 mm long, long-hairy, 1-celled, style short. Fruit a narrowly oblong pod up to 20 cm × 5 cm, flattened, long-attenuate at base, obtuse at apex, slightly curved, woody, brown, 2-valved, 4–9-seeded. Seeds obovoid-ellipsoid, c. 2 cm × 1.5 cm, flattened, glossy. Seedling with epigeal germination.
Xylia comprises 9 species, 6 of which occur in continental Africa, 2 in Madagascar and 1 in tropical Asia. It is related to Calpocalyx, which differs in its spike-like inflorescences.
Xylia xylocarpa (Roxb.) Taub. from tropical Asia is an important timber tree in Myanmar and India, and has occasionally been planted in tropical Africa. The wood is heavy, hard and durable and used for heavy construction. The wood of Xylia hoffmannii (Vatke) Drake is used for furniture in northern Madagascar; a decoction of the pods is taken as a tonic. Xylia hoffmannii is a tree up to 25 m tall, with a bole up to 40 cm in diameter, and is locally common in tall forest on limestone soils.
Young Xylia evansii trees have an annual diameter increment of 0.6–1.4 cm. Seedlings develop ectotrophic mycorrhizae. The trees are often deciduous for a short period. Flowers are produced towards the end of the dry season. The seeds are dispersed by the explosively opening pods at the end of the dry season.
Xylia evansii occurs in evergreen forest, semi-deciduous forest and gallery forest. It is often found on well-drained alluvial soils and on hillsides with deep soils.
Large trees usually occur scattered in the forest, but are locally abundant, e.g. in Sierra Leone and Ghana. In some forest areas of Sierra Leone an average density of 2.7 trees of over 70 cm bole diameter per ha has been recorded. Regeneration is in small to medium-sized forest gaps, but seedlings are usually not abundant. However, the germination rate of seeds in the nursery is fair. Germination starts 4–10 days after sowing. The 1000-seed weight is about 400 g.
Genetic resources and breeding
Xylia evansii does not seem to be in immediate danger of genetic erosion. Although it is restricted to the forest zone of West Africa, it is widespread there, and locally common.
Little is known about Xylia evansii, and more research, especially on propagation and growth rates, is needed to evaluate its possible role in sustainably managed natural production forest in West Africa.
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Correct citation of this article:
Lemmens, R.H.M.J., 2007. Xylia evansii Hutch. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.
various parts of the tree
obtained from The Virtual Field Herbarium