Reutealis trisperma (PROSEA)
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Introduction |
Reutealis trisperma (Blanco) Airy Shaw
- Protologue: Kew Bull. 20: 395 (1967).
- Family: Euphorbiaceae
- Chromosome number: 2n= 22
Synonyms
Aleurites trisperma Blanco (1837), A. saponaria Blanco (1845).
Vernacular names
- Philippine tung, soft lumbang, banucalag nut (En)
- Indonesia: kemiri cina (Java), muncang cina (Sundanese), minyak pakal (oil)
- Philippines: baguilumbang, lumbang balukalad, balokanad (Pilipino), balukanag, lumbang (Bikolano).
Origin and geographic distribution
R. trisperma is native to the Philippines (Luzon, Negros, Mindanao), where it is also occasionally cultivated. It has been planted in Java (Indonesia), where it also became naturalized.
Uses
A drying oil is obtained from the seed of R. trisperma . It was formerly made into a weak soap which was popular with sailors as it lathered with sea water. The oil has been widely utilized in the Philippines for illumination, for lubrication and to caulk ships. The oil is said to be an effective insecticide and can be applied as a wood preservative. It can be used as a drying oil in making paint and varnish when combined with kemiri oil (from seed of Aleurites moluccana (L.) Willd.) or tung oil (from the seed of Vernicia fordii (Hemsl.) Airy Shaw). The wood can be made into tea boxes, matches, wooden shoes and light construction material. Medicinally, sap from the bark has been used to cure scurf and the seed as a strong purgative.
Production and international trade
R. trisperma products are only produced and used locally and production statistics are not available. In the Philippines, it is said to be a major source of drying oil.
Properties
The seed of R. trisperma is made up of a shell or seed coat (35-45%) and a kernel (55-65%). The kernel contains about 55% dark orange oil (dry matter based). The approximate composition of the fatty acids is, according to one analysis: palmitic acid 13%, palmitoleic acid 5%, stearic acid 6%, oleic acid 18%, linoleic acid 23%, linolenic acid 5% and unidentified 30%. Another analysis indicated the following composition: palmitic acid 10%, stearic acid 9%, oleic acid 12%, linoleic acid 19% and α-eleostearic acid 51%. The presence of α-eleostearic acid is characteristic of Aleuritinae and explains the toxicity of the oil. Some physical characteristics of the oil are: specific density 0.89 (25°C), iodine value 160 g/100g, acid value 1.7 mg K per g oil, saponification value 192-200, melting point 2-4°C and solidifying point -6.5°C. The oil turns rancid very quickly unless stored in airtight containers. Although the oil is a drying one, it is not suitable by itself for paint manufacturing. Paint made with R. trisperma oil quickly forms a surface foil that effectively seals the paint from the air and prevents further drying. Mixing the oil with at least an equal amount of the less drying kemiri oil or tung oil overcomes this problem. After oil extraction, the remaining cake can be used as a fertilizer, containing about 6% nitrogen, 1.7% potassium and 0.5% phosphorus. The fresh kernel of the seed has a pleasant, nutty taste, but may cause a burning sensation in the mouth and throat. Consuming even part of a single seed causes violent vomiting within half an hour and diarrhoea within a few hours. The oil may irritate the skin and cause eruptions. The latex from the bark is known to cause dermatitis.
Description
Evergreen tree, up to 15 m tall with stem 60 cm in diameter, bark grey to brown. Young twigs distinctly 5-ribbed, with simple indumentum, soon glabrescent. Leaves alternate, simple; stipules triangular, 4-6 mm × 2-4 mm, early caducous; petiole terete, 0.5-3 cm long, striate, with a conspicuous adaxial groove and at apex 2 sessile, cup-shaped glands 1-2 mm in diameter, exuding sweet sap; blade ovate, (4-)8-16(-28) cm × (2.5-)7-15(-22.5) cm, never lobed, base truncate, cordate or reniform, margin entire, apex acuminate, ending in a sessile, discoid gland; venation pinnate with 4-9 pairs of veins, at base 3-7 veins palmately arranged; lower surface stellate-pubescent, prominently in vein axils. Inflorescence a terminal, numerous-flowered, woolly panicle (pyramidal thyrse), 4-30 cm × 4-21 cm, with simple and stellate hairs; flowers unisexual, in bracteate clusters, protogynous, each major axis terminated by a solitary female flower, lateral cymules male; bracts oblong-triangular, 2-7 mm × 1-3 mm, conspicuously hooded after anthesis; pedicel up to 5 mm long, densely puberulous; flowers regular, small, about 1 cm in diameter, yellow-white, often flushed with pink; calyx bell-shaped, valvately rupturing for half to two thirds its length into 2 or 3 lobes, densely pubescent outside, g1abrous inside; petals 5, free, imbricate, clawed, narrowly obovate-spatulate, rounded at the apex, veins not distinct, glabrous on the inside except for the claw, sericeous outside; disk with 5 fleshy glands (large in male, small in female flowers), and 5 free lobes bearing apically a conspicuous tuft of upwardly directed hairs; male flowers 6-10 mm × 10-13 mm, calyx lobes about 5 mm long and wide, petals 7-13 mm × 2-4 mm, claw 2-3 mm long and basal part adnate to the staminal column; stamens (7-)8(-10), in 2 whorls, filaments united into a column, the 5 outer ones up to 3 mm long, free for about half their length, the 2-5 inner ones up to 5 mm long, united for nearly their entire length; female flowers 7-8 mm × 8-10 mm, calyx lobes about 4 mm long and wide, petals 6-14 mm × 3-5 mm, claw 2-3 mm long, ovary superior, ovoid-subglobose-trigonous, 2-4 mm in diameter, 3-4-locular, densely hairy, styles 3-4, 2 mm long, 2-3-lobed with spatulately flattened stigmas. Fruit capsular, subglobose, 3-5 cm in diameter, velutinous, with 3 or 4 distinct longitudinal ridges, light brown. Seed without caruncula, flattened subglobose, 2-3 cm × 1.5-2 cm, surface smooth; hilum large, brown to maroon with faint dark brown variegations; embryo straight, embedded in copious endosperm; cotyledons flat, broad.
Growth and development
Germination of the seed of R. trisperma takes about 3 weeks and early growth is fairly rapid. On fertile soils, seedlings may grow to a height of 50 cm in 1 year, while trees reach 5 m in 5 years and develop a dense crown with dark green foliage. On poor soils with minimal husbandry in Indonesia, however, most trees only reach a height of 4 m in 10 years. First fruits are collected 8 years after planting, but only some trees older than 10 years produce in quantity. In the Philippines, the fruiting season is from January to July.
Other botanical information
Reutealis Airy Shaw is closely related to Aleurites J.R. Forst. & G. Forst. and Vernicia Lour., together constituting subtribe Aleuritinae (of the tribe Aleuritideae , subfamily Crotonoideae, family Euphorbiaceae ). These three genera were separated from the former single genus Aleurites . R. trisperma is the only species in Reutealis . In contrast to Aleurites , Reutealis has truncate to cordate, never cuneate leaf bases, flowers with 7-10 stamens ( Aleurites 17-32), ovary 3-4-locular ( Aleurites 2-3) and a dehiscent, capsular fruit ( Aleurites drupaceous). Reutealis can be distinguished from Vernicia by its stellate hairs on the leaf underside (hairs simple or bifurcate in Vernicia ), 5-angular twigs (terete in Vernicia ) and a woolly, pyramidal thyrse with flowers about 1 cm in diameter ( Vernicia has a tomentose, corymbiform thyrse with flowers 2-4 cm in diameter).
Ecology
R. trisperma is a rare tree in forests at low to medium altitudes in the Philippines. In western Java, where the tree has been introduced, it is locally naturalized at sea level on poor soils.
Agronomy
R. trisperma is propagated by seed which is recalcitrant. In the Philippines, a planting experiment showed a germination rate of 98% in only 19 days. In the early 1900s in West Java, R. trisperma was sown directly in the field, intercropped with food crops during the first 2-3 years and then left almost untended. In the Philippines, sowing in a nursery and transplanting bare-rooted seedlings into the field gave mixed results. After 4 months, untreated seedlings had a survival rate of only 30%, covering the roots with mud increased the rate to 50%, while treatment with the surfactant Agricol resulted in 75% survival. Diseases and pests are not known to cause serious damage. Fruits are normally collected from the ground, where they may be left for 7-10 days. Alternatively, a light pole with an attached hook may be used to detach fruits from the tree. After collection, the seeds should be processed rapidly as the thin seed coat does not protect the kernel against oxidation of the oil. Usually whole seeds are ground, although removing the seed coat before grinding gives a better quality oil. The seed coat can be easily removed manually after drying the seed. The ground seeds are warm-pressed to extract the oil. The oil should be stored in airtight containers as its quality deteriorates rapidly through oxidation.
Genetic resources and breeding
No germplasm collections or breeding programmes of R. trisperma are known to exist.
Prospects
In spite of the high oil content of its seeds, it seems unlikely that R. trisperma will become an important source of drying oil as several alternative sources are available. The moderate growth rate of the tender seedlings does not favour the inclusion of R. triperma in reforestation programmes.
Literature
- Arias, S.C. & Mendoza, D.R., 1973. The beneficial effect of Agricol compound treatment in bare-root planting of five reforestation crop species. Araneta Research Journal 20: 16-25.
- Arida, V.P., 1982. Products of industrial oils and by-products: its processing and utilization. National Science & Technology Authority Technology Journal 7(1): 88-96.
- Brown, W.H., 1954. Useful plants of the Philippines. Vol. 2. Technical Bulletin 10. Department of Agriculture and Natural Resources. Bureau of Printing, Manila, the Philippines. pp. 292-296.
- de Guzman, E.D., Umali, R.M. & Sotalbo, E.D., 1986. Dipterocarps, nondipterocarps. In: Umali, R.M. et al. (Editors): Guide to Philippine flora and fauna. Vol. 3. Natural Resources Management Center & University of the Philippines, Manila, the Philippines. pp. 293-294.
- Guyat, M.A., Velazquez, D., Perez Zayas, J. & Quintero, M.J., 1991. Obtención y caracterización del aceite de tung a partir de dos especies del genero Aleurites [Extraction and characterization of tung oil from two species of the genus Aleurites] . Revista Baracoa 21: 39-47.
- Heyne, K., 1927. De nuttige planten van Nederlandsch Indië [The useful plants of the Dutch East Indies]. 2nd Edition. Vol. 2. Departement van Landbouw, Nijverheid en Handel in Nederlandsch Indië. pp. 934-936.
- Stuppy, W., van Welzen, P.C., Klinratana, P. & Posa, M.C.T., 1999. Revision of the genera Aleurites, Reutealis and Vernicia (Euphorbiaceae). Blumea 44: 73-98.
- Weismann, G., 1976. Die Samenoele von Aleurites-arten [The seed oils of Aleurites species]. Seifen, Oele, Fette, Wachse 102(3): 77-78.
Authors
N.O. Aguilar & L.P.A. Oyen
