Erismadelphus exsul

Family

Vochysiaceae

Synonyms

Vernacular names

Angoa (Fr).

Origin and geographic distribution

Erismadelphus exsul is distributed from south-eastern Nigeria to DR Congo.

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Uses

In tropical Africa the wood is locally used for rafters of huts. It is suitable for light construction, furniture, interior trim, joinery and plywood.
In traditional medicine in Cameroon, a decoction prepared from a boiled mixture of the bark of Erismadelphus exsul together with the barks of Albizia adianthifolia (Schumach.) W.Wight, Cola lateritia K.Schum., Garcinia kola Heckel, Ongokea gore (Hua) Pierre and Vernonia conferta Benth. is drunk for the treatment of urinary lithiasis.

Production and international trade

The wood is used domestically and hardly or not traded on the international market.

Properties

The heartwood is yellowish brown, frequently with greenish brown markings near the centre of the log, and indistinctly demarcated from the yellowish sapwood. The grain is usually straight, sometimes interlocked, texture moderately coarse. The wood is medium-weight, with a density of 630–800 kg/m³ at 12% moisture content. It air dries moderately fast with little tendency of splitting and checking, but twisting or cupping may occur. Thicker boards may be subject to collapse. The shrinkage rates are high, from green to oven dry 4.6–7.6% radial and 8.0–13.9% tangential. Once dry, the wood is moderately stable to unstable in service.
At 12% moisture content, the modulus of rupture is 117–160 N/mm², modulus of elasticity 11,000–17,700 N/mm², compression parallel to grain 44–67 N/mm², shear 5.5–9 N/mm², cleavage 5–17 N/mm and Chalais-Meudon side hardness 3.1–6.5.
The wood saws easily, but with considerable blunting effect because it contains 0.1–0.5% silica; the use of stellite-tipped saw teeth is recommended. It works moderately well with both hand and machine tools. Some picking up of grain may occur during planing, and it is necessary to take extra caution in sanding and finishing. The wood polishes to a good finish when a filler is used. The nailing properties are good and the gluing properties satisfactory. The steam bending properties are poor. The wood is only moderately durable, being liable to most insect attacks. The sapwood is susceptible to attacks by Lyctus borers. Both heartwood and sapwood are moderately resistant to treatment with preservatives.

Description

Medium-sized to large tree up to 40(–70) m tall; bole branchless for up to 25 m, straight and cylindrical, up to 100(–150) cm in diameter, often with thin buttresses; bark surface grey to reddish brown, smooth when young, later becoming rough and scaly, inner bark thin, granular, hard but brittle, pale brown or pale pink; crown with spreading branches; twigs slightly quadrangular, glabrous. Leaves opposite, simple and entire; stipules reduced to small warts; petiole 0.5–1.5 cm long, flattened, glabrous or hairy; blade obovate to elliptical, 4–20(–25) cm × 3–11 cm, cuneate to rounded or cordate at base, obtuse to acuminate at apex, leathery, glabrous or hairy on midrib and lateral veins below, pinnately veined with 5–10 pairs of lateral veins. Inflorescence a terminal, umbel-like panicle 10–25 cm long, with opposite branches bearing condensed, 3–4-flowered cymes, hairy, many-flowered; bracts sessile, kidney-shaped to heart-shaped, 7–8 mm × 8–10 mm, persistent. Flowers bisexual, zygomorphic, 5-merous, sessile; calyx spurred, lobes nearly equal, oblong to nearly orbicular, up to 7.5 mm × 5 mm, hairy, greenish yellow; petals free, obovate-rhomboid, 9–10 mm × 4.5–6 mm, with a long claw, finely hairy, white; fertile stamen 1, c. 3 mm long, rudimentary stamens 1–3, club-shaped; ovary inferior, 1-celled, style short. Fruit a globose nut c. 8 mm in diameter, brownish, indehiscent, 1-seeded, with sepals enlarged into unequal wings up to 8 cm × 2.5 cm.

Other botanical information

Erismadelphus comprises 2 species. Erismadelphus sessilis Keay & Stafleu occurs in Cameroon, Equatorial Guinea and Gabon, and is apparently rare; it differs from Erismadelphus exsul in its sessile and smaller leaves.
Within Erismadelphus exsul 2 varieties have been distinguished: var. exsul distributed in Cameroon, Gabon, Congo and DR Congo, and var. platyphyllus Keay & Stafleu distributed in Nigeria, Cameroon, Equatorial Guinea and Gabon; the latter has more hairy leaves.

Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 27: intervessel pits large (≥ 10 μm); 29: vestured pits; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 43: mean tangential diameter of vessel lumina ≥ 200 μm; 46: ≤ 5 vessels per square millimetre; (47: 5–20 vessels per square millimetre); 56: tyloses common. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 70: fibres very thick-walled. Axial parenchyma: 83: axial parenchyma confluent; 85: axial parenchyma bands more than three cells wide; 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand. Rays: 96: rays exclusively uniseriate; 109: rays with procumbent, square and upright cells mixed throughout the ray; 115: 4–12 rays per mm. Secretory elements and cambial variants: 133: included phloem, concentric; 134: included phloem, diffuse. Mineral inclusions: 159: silica bodies present; 160: silica bodies in ray cells; 161: silica bodies in axial parenchyma cells.
(C. Essien, H. Beeckman & P.E. Gasson)

Growth and development

In Nigeria flowering is in April–August and fruiting in June–November. The fruits with their enlarged wing-like sepals are dispersed by wind. In Gabon seedlings have been reported in the understorey of old forest.

Ecology

Erismadelphus exsul occurs in lowland primary and secondary forest, also in littoral forest, swamp forest and riverine forest. In Gabon littoral savanna is colonized by pioneer species such as Aucoumea klaineana Pierre, which are progressively replaced by other species including Erismadelphus exsul.

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Management

Erismadelphus exsul trees usually occur scattered in the forest, sometimes in small, occasionally large groups. In Gabon as many as 40 trees per hectare were counted in littoral forest, whereas the mean wood volume in forest in Gabon has been reported to be 2 m³ per ha. In forest dominated by Aucoumea klaineana Pierre and Sacoglottis gabonensis (Baill.) Urb., the standing volume of Erismadelphus exsul has been estimated at 10 m³/ha.

Harvesting

In Gabon the minimum bole diameter allowed for harvesting Erismadelphus exsul trees is 70 cm.

Genetic resources and breeding

Although Erismadelphus exsul has a limited distribution, it is probably not threatened by genetic erosion since there are no indications of over-exploitation within its range.

Prospects

Because of its limited durability and its instability in service the wood of Erismadelphus exsul does not have a wide range of uses. It may have some potential for use for interior joinery, furniture and plywood. If Erismadelphus exsul would become more important as a source of timber, more information would be required on its abundance, regeneration and growth rate to make sustainable exploitation possible.

Major references

• Anonymous, 1990. Neuere Importhölzer aus Afrika: angoa (Erismadelphus exsul Mildbr., Familie der Vochysiaceae). Holz-Zentralblatt 116(21): 300.
• 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.
• Burkill, H.M., 2000. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S–Z, Addenda. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 686 pp.
• de Saint-Aubin, G., 1963. La forêt du Gabon. Publication No 21 du Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 208 pp.
• Keay, R.W.J. & Stafleu, F.A., 1953. Erismadelphus. Acta Botanica Neerlandica 1(4): 594–599.
• Robyns, W., 1958. Vochysiaceae. In: Robyns, W., Staner, P., Demaret, F., Germain, R., Gilbert, G., Hauman, L., Homès, M., Jurion, F., Lebrun, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 7. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 235–238.
• Sallenave, P., 1971. Propriétés physiques et mécaniques des bois tropicaux. Deuxième supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 128 pp.
• Senterre, B. & Obiang, D., 2005. Nouvelles découvertes à propos des Vochysiaceae africaines: Erismadelphus Mildbr. et Korupodendron Litt & Cheek. Taxonomania 17: 3–18.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.

Other references

• Boulvert, Y., 1977. Catalogue de la flore de Centrafrique: ecologie sommaire et distribution. Tome 1. Forêts denses et galeries forestières. Texte provisoire. ORSTOM, Bangui, Central African Republic. 465 pp.
• Kawasaki, M.L., 2007. Vochysiaceae. In Kubitzki, K. (Editor). Families and genera of vascular plants. Vol. 9. Flowering plants, Eudicots. Springer, Berlin, Germany. pp. 480–487.
• Keay, R.W.J., 1954. Vochysiaceae. In: Keay, R.W.J. (Editor). Flora of West Tropical Africa. Volume 1, part 1. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. p. 114.
• Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.
• Kenfack, D., undated. Vascular plants of Korup national park. Erismadelphus exsul Mildbr. [Internet] http://korupplants.lifedesks.org/ pages/715. Accessed August 2011.
• Normand, D. & Paquis, J., 1976. Manuel d’identification des bois commerciaux. Tome 2. Afrique guinéo-congolaise. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 335 pp.
• Noumi, E. & Ebwelle, E.S., 2011. Potentiality of medicinal plants in treating urinary lithiasis in Littoral region, Cameroon. European Journal of Medicinal Plants 1(3): 74–87.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 pp.
• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 129 pp.
• Sallenave, P., 1964. Propriétés physiques et mécaniques des bois tropicaux. Premier supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 79 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.

Afriref references

Sources of illustration

• Keay, R.W.J. & Stafleu, F.A., 1953. Erismadelphus. Acta Botanica Neerlandica 1(4): 594–599.
• Robyns, W., 1958. Vochysiaceae. In: Robyns, W., Staner, P., Demaret, F., Germain, R., Gilbert, G., Hauman, L., Homès, M., Jurion, F., Lebrun, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 7. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 235–238.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.

Author(s)

•	E.E. Ewudzie Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
•	J.R. Cobbinah Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
•	S. Britwum Acquah Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
•	E.A. Obeng Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Editors

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	D. Louppe CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C 105 / D (Bât. C, Bur. 113), 34398 Montpellier Cédex 5, France
•	A.A. Oteng-Amoako Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Associate editors

•	E.A. Obeng Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Photo editor

•	G.H. Schmelzer PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Ewudzie, E.E. & Cobbinah, J.R. & Britwum Acquah, S. & Obeng, E.A., 2012. Erismadelphus exsul Mildbr. [Internet] Record from PROTA4U. Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>. Accessed .

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