Prota 14: Vegetable oils/Oléagineux
Notizbl. Bot. Gart. Berlin-Dahlem 7: 483 (1921).
2n = 22
Licania elaeosperma (Mildbr.) Prance & F.White (1976).
Po-yok, mahogany nut, nikko (En). Po-yok (Fr).
Origin and geographic distribution
Afrolicania elaeosperma occurs from Guinea and Sierra Leone to the Central African Republic, Gabon and Congo.
The seed oil is used as a hair oil and body scent. It was formerly used as a substitute for linseed oil in paints and varnishes, and as a poor substitute for tung oil.
Production and international trade
There is some export of the oil, e.g. from Ghana, but amounts involved are not known.
The stones from the fruits weigh about 9.5 g of which 58–67% is kernel. The kernels contain 40–58% oil. The fatty acid composition of the oil is: saturated fatty acids 13%, mono-unsaturated fatty acids 9%, licanic acid 44% and eleostearic acid 34%. Due to the high content of licanic acid (4-oxo-9,11,13-octadecatrienoic acid) and eleostearic acid, the oil is drying and solidifies rapidly into a varnish-like mass. The main commercial source of licanic acid is oiticica oil from Licania rigida Benth. from tropical America, which contains up to 80%. The presscake of Afrolicania elaeosperma remaining after oil extraction is not suitable as cattle feed.
Small tree up to 15 m tall; bole irregular and with long, deep grooves, up to 50(–80) cm in diameter, with buttresses up to 2 m high; outer bark brown with greyish or greenish patches, slightly rough, inner bark dark red to pink-orange, granular; crown hemispherical, dense; branches glabrous when young. Leaves alternate, simple and entire; stipules linear, 3–6 mm long, long persistent, margins minutely toothed; petiole 0.5–1 cm long, grooved above, with 2 glands; blade elliptical, 7–16 cm × 3–8 cm, base cuneate, apex acuminate, leathery, glabrous on both surfaces when mature, pinnately veined with 7–10 pairs of lateral veins. Inflorescence a terminal or axillary panicle up to 25 cm long with flowers in groups of 2–3(–5), sparsely grey pubescent. Flowers bisexual or male, regular, c. 2 mm long; pedicel 1–2 mm long; receptacle flattened, pubescent outside; calyx lobes 5, triangular, grey pubescent; petals absent; stamens c. 20, free, short; ovary superior, c. 1 mm long, 1-celled, style c. 1 mm long. Fruit a dry, ovoid drupe c. 5 cm long, densely warty, golden brown, 1-seeded; endocarp thin, hard but brittle, hairy inside. Seed with thick, fleshy cotyledons. Seedling with hypogeal germination; first leaves alternate.
Afrolicania comprises a single species. It is closely related to Licania and has long been included in this genus as the sole African representative, but molecular and morphological evidence suggests that it is better separated.
Trees are slow to mature and 20–30-year old trees are known that still do not bear fruit. Fruits may be dispersed by water.
Afrolicania elaeosperma occurs in coastal and riverine primary and secondary forest in the Guineo-Congolian rainforest zone, sometimes on the land-side behind mangroves. In Cameroon it always occurs in seasonally flooded forest. It often grows on very poor sandy soils.
The fruits are collected from wild stands, often from the shore. In Sierra Leone they are collected in March–June. The stone of the fruit is brittle and the oily kernel is easily removed from it.
Genetic resources and breeding
Afrolicania elaeosperma has a large distribution area and it is unlikely that it is threatened by genetic erosion, although it has a scattered distribution.
Although the oil has interesting chemical properties, it is unlikely that it will become more important as an industrial oil as the very long juvenile period of Afrolicania elaeosperma makes it uneconomical as a plantation species.
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.
• Letouzey, R. & White, F., 1978. Chrysobalanaceae. Flore du Cameroun. Volume 20. Muséum National d’Histoire Naturelle, Paris, France. pp. 3–138.
• Prance, G.T. & Sothers, C.A., 2003. Chrysobalanaceae 1: Chrysobalanus to Parinari. Species Plantarum: Flora of the World. Part 9. Australian Biological Resources Study, Canberra, Australia. 319 pp.
• Savill, P.S. & Fox, J.E.D., 1967. Trees of Sierra Leone. Forest Department, Freetown, Sierra Leone. 316 pp.
• Anonymous, 1942. Po-yok fruits from Sierra Leone. Bulletin of the Imperial Institute, London 40(2): 99–103.
• Fauve, M., 1944. Postwar drying oils in the paint and varnish industry. Peintures, Pigments, Vernis 20: 43–47.
• Kunkel, G., 1966. Anmerkungen über Sekundärbusch und Sekundärwald in Liberia (Westafrika). Plant Ecology 13: 233–248.
• Lemée, G., 1959. Effets des charactères du sol sur la localisation de la végétation en zones équatoriale et tropicale humide. [Internet] Tropical Soils and Vegetation. Symposium held in Abidjan, 20–24 October 1959. UNESCO, Paris, France. pp. 25–39. http://unesdoc.unesco.org/ images/0001/000194/ 019446mo.pdf. Accessed December 2006.
• Rheineck, A.E., 1937. A note on Po-yok oil. Paint, Oil and Chemical Review 99(9): 7–8.
Correct citation of this article:
Oyen, L.P.A., 2007. Afrolicania elaeosperma Mildbr. In: van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA 14: Vegetable oils/Oléagineux. [CD-Rom]. PROTA, Wageningen, Netherlands.