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Soyauxia floribunda Hutch.

Protologue
Kew Bull. 1915: 44 (1915).
Family
Medusandraceae (APG: Peridiscaceae)
Origin and geographic distribution
Soyauxia floribunda is distributed in Gambia, Sierra Leone, Liberia and Côte d’Ivoire. Records of the species from Gabon are almost certainly based on misidentifications.
Uses
The twigs of Soyauxia floribunda are used in Sierra Leone as chew-sticks for children to clean the teeth. The flexible stems are made into hoops for fishing nets. To make a thorn come out of a wound, a poultice made of roasted bark is applied to the wound.
Botany
Shrub or small tree up to 12(–18) m tall; bole fluted, inner bark thin, granular, red; crown spreading; young branches densely hairy, twigs flat. Leaves arranged spirally, simple and entire; stipules paired, oblong, soon falling; petiole short; blade oblong to elliptical, 8–27 cm × 3–8 cm, rounded at base, long acuminate at apex, leathery, glossy, glabrous beneath when mature, pinnately veined with more than 12–16 pairs of distinct lateral veins. Inflorescence an axillary or terminal raceme with flowers scattered, up to 12 cm long. Flowers bisexual, regular, 5-merous; pedicel very short; sepals ovate, c. 4 mm long, persistent in fruit, glabrous but for some short hairs at base; petals free, white, as long as sepals; corona short, tubular; stamens many, filaments long and thin, anthers 4-celled; ovary superior, 1-celled, styles 3, long and exserted. Fruit an oblong, sessile, 3-valved capsule 12–18 mm long, 1-seeded. Seed trigonous, black, c. 15 mm long. Seedling with hypogeal germination; first 2 leaves opposite, simple.
Soyauxia floribunda flowers in April–September and fruits in August–February.
Soyauxia comprises about 6 species, distributed in West and Central Africa. It has been placed in Flacourtiaceae and Passifloraceae and resembles some Euphorbiaceae. More recently it has been included in Medusandraceae, but the most modern approach is to place it in Peridiscaceae, together with 2 genera from tropical America. The closely related Soyauxia gabonensis Oliv. is a small tree of up to 3 m tall that produces edible fruits, and is found in rainforest in Nigeria, Cameroon and Gabon.
Ecology
Soyauxia floribunda occurs from sea-level up to 700 m altitude, most often in rainforest, rarely in semi-deciduous forest; it is conspicuous in forest regrowth. In Côte d’Ivoire Soyauxia floribunda is exclusively found in Diospyros-Mapania forest on soils derived from schists. On the sandy soils of the south it is absent and northward it extends up to the 1700 mm isohyet.
Management
The 1000-seed weight is about 500 g.
Genetic resources and breeding
Soyauxia floribunda is not present in any germplasm collection. The species apparently has a wide distribution and only widespread loss of habitat would form a serious threat.
Prospects
Soyauxia floribunda will remain useful only locally.
Major references
• Aubréville, A., 1959. La flore forestière de la Côte d’Ivoire. Deuxième édition révisée. Tome troisième. Publication No 15. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 334 pp.
• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.
• Keay, R.W.J., 1958. Medusandraceae. In: Keay, R.W.J. (Editor). Flora of West Tropical Africa. Volume 1, part 2. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 652–656.
• Lisowski, S., 2009. Flore (Angiospermes) de la République de Guinée: première partie. Scripta Botanica Belgica. Volume 41. Jardin Botanique National de Belgique, Belgium. 517 pp.
Other references
• Bayer, C., 2007. Peridiscaceae. In: Kubitzki, K. (Editor). The families and genera of vascular plants. Vol. 9. Flowering plants - Eudicots. Springer-Verlag, Berlin, Heidelberg, Germany. pp. 297–300.
• Brenan, J.P.M., 1953. Soyauxia, a second genus of Medusandraceae. Kew Bulletin 8: 507–511. • de la Mensbruge, G., 1966. La germination et les plantules des essences arborées de la forêt dense humide de la Côte d’Ivoire. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 389 pp.
• Hawthorne, W. & Jongkind, C., 2006. Woody plants of western African forests: a guide to the forest trees, shrubs and lianes from Senegal to Ghana. Kew Publishing, Royal Botanic Gardens, Kew, United Kingdom. 1023 pp.
• Normand, D., 1960. Atlas des bois de la Côte d’Ivoire. Tome 3. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 182 pp.
• 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.
• Nyanayo, B.L., 1986. Pollen morphology and its taxonomic significance in the West African Medusandraceae (Rosidae). Journal of Plant Science Research 2(1): 125–128.
• Portères, R., 1974. Un curieux élément culturel Arabico-Islamique et Néo-Africain : les baguettes végétales machées servant de frotte-dents. Journal d’Agriculture Tropicale et de Botanique Appliquée 21(4–6) : 1–36; 111–149.
• Savill, P.S. & Fox, J.E.D., 1967. Trees of Sierra Leone. Forest Department, Freetown, Sierra Leone. 316 pp.
• White, F., 1978. The taxonomy, ecology and chorology of African Ebenaceae I. The Guineo Congolian species. Bulletin du Jardin Botanique National de Belgique 48: 245–358.
Author(s)
C.H. Bosch
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
E.G. Achigan Dako
PROTA Network Office Africa, World Agroforestry Centre (ICRAF), P.O. Box 30677-00100, Nairobi, Kenya

Correct citation of this article:
Bosch, C.H., 2011. Soyauxia floribunda Hutch. In: Brink, M. & Achigan-Dako, E.G. (Editors). Prota 16: Fibres/Plantes à fibres. [CD-Rom]. PROTA, Wageningen, Netherlands.
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