Prota 7(2): Timbers/Bois d’œuvre 2
Bot. Jahrb. Syst. 45: 295, fig. 1 (1910).
Caesalpiniaceae (Leguminosae - Caesalpinioideae)
Eurypetalum batesii Baker f. (1929).
Origin and geographic distribution
Eurypetalum tessmannii occurs in southern Cameroon, Equatorial Guinea and Gabon.
The wood is used locally for construction, joinery and carpentry. In Gabon it is considered durable and used for house construction.
The heartwood is coppery reddish brown and distinctly demarcated from the whitish to pale orange-yellow sapwood. The texture is fine. The wood is rather heavy and hard. A red dye is present in the wood.
Medium-sized to fairly large tree up to 40 m tall; bole up to 90 cm in diameter, often with many upright sprouts at base or several boles together, with buttresses, sometimes with air roots; bark surface fissured, reddish grey to dark grey or blackish, inner bark thin, fibrous; twigs usually glabrous, with lenticels. Leaves alternate, paripinnately compound with 4 leaflets; stipules ovate-lanceolate to elliptical, up to 2 cm long; petiole 1–2(–3.5) cm long, rachis 1–9 cm long; petiolules 4–8 mm long; leaflets at base of leaf alternate to opposite, at apex of leaf opposite, usually obovate-elliptical, (4.5–)6–11.5(–17) cm × (2–)2.5–6(–8.5) cm, acuminate at apex, leathery, glabrous, with marginal gland near base and with translucent dots. Inflorescence an axillary panicle up to 10 cm long, short-hairy, with long branches. Flowers unisexual or polygamous, zygomorphic, whitish; pedicel 2–7 mm long; sepals 4, ovate-oblong, 3–6 mm long, slightly unequal, glabrous; petals 5, free, 1 large and kidney-shaped, 4–8 mm × 7–17 mm, the other very small; stamens 10, in 2 whorls, 9 shortly fused at base, 1 free, up to 11.5 mm long; ovary superior, 1–1.5 mm long, hairy, with short stipe at base, style slender, curved; male flowers with reduced ovary, female flowers with reduced stamens. Fruit an obovate, flattened pod 8–11 cm × 4–5 cm, hairy, with short stipe at base, dehiscing by 2 woody valves, 1–2-seeded. Seeds elliptical to nearly round, flattened, 4–6 cm long, glabrous, brown. Seedling with epigeal germination; hypocotyl 1.5–5 cm long, epicotyl 7–13 cm long; cotyledons thick, fleshy, with fringes at base; first leaves alternate, with 2–4 pairs of leaflets.
In the forest, trees are often surrounded by sprouts from the base of the bole; these sprouts may form circles of up to 5 m in diameter. The flowers are possibly functionally unisexual. Trees with only apparently male flowers are more common than trees with apparently female flowers, in a proportion of approximately 4:1. The fruits are explosively dehiscent with spiralling valves, dispersing the seeds over some distance.
Eurypetalum comprises 2 species. It has been placed close to Eperua from tropical America, which has a similar flower structure but differs in wood anatomy and the presence of nectary glands.
The wood of Eurypetalum unijugum Harms, a medium-sized tree up to at least 20 m tall with bole up to 80 cm in diameter and endemic to Cameroon, is probably used in the same way as that of Eurypetalum tessmannii. Eurypetalum unijugum is characterized by a single pair of leaflets.
Eurypetalum tessmannii occurs in lowland rainforest up to 350 m altitude, in primary and old secondary forest.
Genetic resources and breeding
Eurypetalum tessmannii is fairly widespread in Central Africa, and does not seem to be subject to threats because it is not selectively logged. However, Eurypetalum unijugum is classified as vulnerable because it occurs only in Cameroon, and is there rare and threatened by forest clearance.
Eurypetalum tessmannii is poorly known, also concerning its wood properties. However, it will probably remain of only local importance because it is often multi-stemmed with most boles of comparatively small diameter and its wood is hard and heavy without very attractive appearance. However, its vegetative way of propagation by sprouting may offer good possibilities for multiplication e.g. for reafforestation programmes.
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Correct citation of this article:
Lemmens, R.H.M.J., 2010. Eurypetalum tessmannii Harms. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.