Prota 7(1): Timbers/Bois d’œuvre 1
Bot. Jahrb. Syst. 18: 169 (1894).
Verbenaceae (APG: Lamiaceae)
2n = 32
Origin and geographic distribution
Vitex grandifolia occurs from Sierra Leone east to Cameroon and Gabon.
The wood is used on a local scale for light construction, drums and canoe seats. It is suitable for light flooring, joinery, interior trim, furniture, cabinet work, toys, novelties, shipbuilding, vehicle bodies, agricultural implements, boxes, crates, veneer, plywood and pulpwood. The fruits are edible and used to make an alcoholic drink. In traditional medicine the bark is used as a stomachic and to treat diarrhoea, bronchial complaints, rickets, sores and fever. Leaves are used in medications against colic, infections of the umbilical cord, toothache, rheumatism and orchitis. A tea made from the fruits is drunk as a tonic. The black juice exuding from leaves heated over a fire has been used as ink.
Production and international trade
The timber of Vitex grandifolia is used locally, although there are also reports on export to Europe from Cameroon and Gabon.
The heartwood is whitish to pale brown, darkening on exposure to brown, and indistinctly demarcated from the sapwood. The grain is usually straight, texture medium. The wood has a density of about 490 kg/m³ at 12% moisture content. The wood air-dries fairly easily, but has a tendency to cup; it may be reconditioned by steaming. The rates of shrinkage are moderately high: from green to oven dry 4.0% radial and 6.4% tangential. Once dried, the wood is moderately stable in service.
At 12% moisture content, the modulus of rupture is about 88 N/mm², modulus of elasticity 7700 N/mm², compression parallel to grain 35 N/mm², shear 8 N/mm², cleavage 15 N/mm and Chalais-Meudon side hardness 2.5.
The wood is easy to saw and work with hand and machine tools. It generally planes to a smooth surface and finishes well. The wood nails well without splitting. Veneer of good quality can be produced. The wood is moderately durable and reportedly resistant to termite attack. The sapwood is susceptible to Lyctus beetle attack. The heartwood is moderately resistant to impregnation by preservatives; the sapwood is fairly permeable.
Evergreen shrub or small to medium-sized tree up to 20 m tall; bole branchless for up to 15 m but usually much shorter, up to 60(–120) cm in diameter, often sinuous and slightly fluted at base; bark surface grey to reddish brown or greenish yellow, finely scaly, inner bark yellowish, rapidly darkening on exposure; young branches obtusely quadrangular, short-hairy or glabrous. Leaves opposite, digitately compound with 5(–7) leaflets; stipules absent; petiole 9–20 cm long, stout; petiolules up to 5(–10) mm long; leaflets obovate, 13–40 cm × 6–20 cm, acuminate at apex, entire, thin-leathery, glabrous. Inflorescence an axillary, compact cyme up to 7 cm long, many-flowered; peduncle up to 5 cm long. Flowers bisexual, zygomorphic, 5-merous; calyx 3–6 mm long, enlarging in fruit, with obscure teeth, finely hairy; corolla pale purple with yellowish limb, 15–20 mm long, finely hairy; stamens 4, inserted in the corolla tube, 2 long and 2 short; ovary superior, globose, 4-celled, glabrous but hairy at apex, style slender, curved. Fruit an ellipsoid to globose drupe 1.5–2 cm long, yellowish when ripe but later becoming black, fleshy, with woody, 4-celled stone, up to 4-seeded. Seeds without endosperm. Seedling with epigeal germination; hypocotyl 3–4 cm long, epicotyl 10–14 mm long; cotyledons thinly leathery, short-stalked; first pairs of leaves simple.
In Côte d’Ivoire Vitex grandifolia trees can be found flowering almost throughout the year and fruits mature in March to May and October.
Vitex comprises about 150 species and is pantropical with a few species in temperate regions. Approximately 60 species can be found in tropical Africa.
Vitex grandifolia is often an understorey tree of lowland evergreen forest. In many regions it is rather uncommon, e.g. in Ghana and Gabon, but in other regions it may be locally common, especially in secondary forest, e.g. in Côte d’Ivoire and Cameroon.
Seeds start to germinate 2–3 months after sowing. The germination rate may be up to 90%. In forest near Edéa (Cameroon) the average timber volume was recorded at 0.65 m³/ha. Logs are liable to blue stain attack and should be treated with preservatives or removed from the forest soon after felling.
Genetic resources and breeding
There are no reasons to consider Vitex grandifolia as threatened by genetic erosion because it is fairly widespread, at least locally common and also present in disturbed forest.
Too little is known on ecology, growth rates and natural regeneration of Vitex grandifolia to judge its prospects as a timber tree in sustainably managed forest. However, the often poor shape and small size of the bole seem to limit its possibilities for commercial exploitation.
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Correct citation of this article:
Lemmens, R.H.M.J., 2008. Vitex grandifolia Gürke. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.