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14: Vegetable oils and fats

Pittosporum resiniferum Hemsl.

PITTOSPORACEAE

Pittosporum acuminatissimum Merr., Pittosporum epiphyticum Merr.

Petroleum nut tree (En). Philippines: hanga (Tagalog), abkel (Igorot), bualau (Bikolano).

Northern Borneo (Malaysia), the Philippines, Solomon Islands. It is occasionally grown elsewhere, e.g. as an ornamental in California (United States).

The fruit contains about 20% of a light oil, smelling like petroleum. Even the unripe fruit burns brightly and readily and has been used for illumination and as fuel source. The fuel properties of steam-distilled oil from fruits after hydrogenation are quite comparable to those of gasoline. In the Philippines, the fruit has been used medicinally as a panacea, particularly to treat abdominal pain, the oleoresin for muscular pain and skin diseases and a decoction for colds. The wood is used for indoor constructions and for fuel. The tree is also planted as an ornamental.

Small tree or shrub, often epiphytic, 2—5(—30) m tall. Leaves spirally arranged, coriaceous, glabrous; petiole 2—4 cm long; blade obovate to oblanceolate, 6—21 cm x 3—6 cm, base cuneate, margin entire, apex acuminate, veins 7—10 pairs, prominent beneath. Inflorescence with flowers in a fascicle or arranged umbel-like, usually on bare branches below the leaves; pedicel 2—10 mm long; flowers 5-merous, white, fragrant; sepals 2—4 mm long, at base connate into a shallow cup; petals narrowly oblong, 9—12 mm x 1—2 mm; filaments 6—7 mm long; ovary sessile, ellipsoid, 4—5 mm x 1—2 mm, densely pubescent, style 2 mm long, stigma thickened. Fruit a subglobose capsule, 2—4 cm in diameter, yellow-black, dehiscing lengthwise into 2 very hard valves 4—5 mm thick, with large resiniferous cavities and numerous seeds. Seed irregular, 4 mm long, shiny black. Pittosporum resiniferum grows in mountain forest (mossy forest) on exposed ridges, at 1000—3000 m altitude, as small tree or epiphyte, in lower localities (400—600 m altitude) exclusively epiphytic. Propagation is possible by seed, cuttings and air layering. Seed remains viable for about 1 month, germination rate is about 75%, rooting rate in cuttings about 60%, 100% in air layering. In the Philippines flowering is from February—April. As its name 'petroleum nut tree' indicates, the 'oil' from Pittosporum resiniferum is not a true oil but a petroleum-like mixture of hexane, nonane and monoterpenes ('ALFA'-pinene, ß-pinene, and smaller amounts of limonene and myrcene). The presence of hexane and nonane is remarkable as alkanes are rare in plants. In the Philippines Pittosporum resiniferum has become very rare, due to overlogging and shifting cultivation, and deserves protection and propagation. Germplasm collections are being made by the Ecosystem Research and Development Bureau (ERDB - formerly Forestry Research Institute) of the Philippines. Experimental plantings for fuel production were promising: 18 kg fruits per tree per year with an average oil yield of 20% would result in an annual yield of oil per ha of about 3000 litres. Usually, oil yield is only 5—7% and breeding for high-yielding cultivars is a first priority. Other Pittosporumspecies in South-East Asia can also have oil-rich seeds, e.g. Pittosporum ferrugineum Aiton and Pittosporum pentandrum (Blanco) Merr.

[18] Brown, W.H., 1951—1957. Useful plants of the Philippines. Reprint of the 1941—1943 edition. 3 volumes. Technical Bulletin 10. Department of Agriculture and Natural Resources. Bureau of Printing, Manila, the Philippines. Vol. 1 (1951) 590 pp., Vol. 2 (1954) 513 pp., Vol. 3 (1957) 507 pp.
[22] Calvin, M., 1985. Fuel oils from higher plants. In: Fuller, K.W. & Gallon, J.R. (Editors): Plant products and the new technology. Annual Proceedings of the Phytochemical Society of Europe 26: 147—160.
[33] Duke, J.A., 1989. CRC handbook of nuts. CRC Press Inc., Boca Raton, Florida, United States. 343 pp.
[42] Flora Malesiana (Various editors), 1950—. Many volumes. Kluwer Academic Publishers, Dordrecht and Flora Malesiana Foundation, Leiden, the Netherlands.
[87] Nemethy, E.K. & Calvin, M., 1982. Terpenes from Pittosporaceae. Phytochemistry 21: 2981—2982.
[91] Noble, B.F. & Ovallo, C.A., 1983. Pre-germination treatment and survival of petroleum nut (Pittosporum resiniferum Hemsl.). Sylvatrop 8: 39—45.
[105] Ronquillo, S.P.D. & Tangan, F.T., 1983. Vegetative propagation of petroleum nut tree (Pittosporum resiniferum Hemsl.) by cuttings. Sylvatrop 8: 61—66.
[131] Veracion, V.P. & Bersamin, J.B., 1983. Marcottage of petroleum nut (Pittosporum resiniferum Hemsl.). Sylvatrop 8: 67—71.

B. Umali

Umali, B.E., 2001. Pittosporum resiniferum Hemsl.. In: van der Vossen, H.A.M. and Umali, B.E. (Editors): Plant Resources of South-East Asia No 14: Vegetable oils and fats. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea