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18: Plants producing exudates

Manihot glaziovii Müll.Arg.

Euphorbiaceae

Ceara rubber tree (En). Caoutchoutier de Céara (Fr). Indonesia: singkong karet (Indonesian), sampeu karet (Sundanese), tela karet (Javanese). Malaysia: pokok chat.

Manihot glaziovii originates from north-eastern Brazil between the southern degrees of latitude 0—10. It is occasionally cultivated pantropically, including South-East Asia.

In the early 1900s the latex was collected commercially to produce rubber, but eventually para rubber from Hevea ousted all other rubber sources. In Africa the leaves are used as a vegetable. In Indonesia Manihot glaziovii scions are grafted on cassava rootstocks (Manihot esculenta Crantz) to increase the yield of storage roots (Mukibat method). The plant is also planted as an ornamental. In breeding work in cassava, Manihot glaziovii has been used as a source to improve vigour and resistance to drought, to mosaic virus disease and to bacterial disease.

Deciduous, monoecious shrub or small tree, up to 15 m tall, trunk 20—30 cm in diameter at base, containing copious latex, bearing tuberous roots. Leaves alternate, peltate, often with a bluish-white bloom; petiole 20(—45) cm long; blade palmately 3(—5) lobed, median lobe obovate about 15(—25) cm x 7(—10) cm, entire, lateral lobes prominently asymmetrical and curved upwards. Inflorescence a terminal panicle, about 30 cm long, profusely branched, many flowered, with setaceous bracts and bracteoles; female flowers restricted to the base of the upper 2/3 of the inflorescence, pedicel up to 2 cm long, flowers large, tepal 1.5 cm long, cleft to the base into 5 strap- shaped lobes, greenish-yellow with purplish tinge, disk prominent, stigma trifid and many-lobed; male flowers in the apical part of the inflorescence, large, tepal 1.5 cm long, cleft 1/3 way down into 5 lobes, green-yellow with purplish pigmentation, disk prominent, stamens 10 in 2 whorls of 5. Fruit a capsule, 2 cm long, dehiscing septicidally. Seed rounded, 1.5 cm in diameter, with trapeziform caruncle. In its native area Manihot glaziovii occurs up to 750 m altitude in a pronounced seasonal climate with a half year rainy season and a half year dry season. The latex is harvested in the dry season, when the plant is leafless and older than 5 years. In South-East Asia it only grows well in the driest areas. In large-scale experimental plantings in East Africa around 1900, a 4-year-old tree yielded about 0.1 kg rubber per year, and about 0.4 kg when 7 years old. In general, the rubber had a high resin content. In Java Manihot glaziovii has been tried on a large scale as well, but the soils and climate were much better suited for Hevea rubber.

[11]Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. 2nd Edition. Ministry of Agriculture and Co-operatives, Kuala Lumpur, Malaysia. Vol. 1 (A–H) pp. 1–1240, Vol. 2 (I–Z) pp. 1241–2444.
[23]Heyne, K., 1927. De nuttige planten van Nederlands-Indië [The useful plants of the Dutch East Indies]. 2nd Edition, 3 volumes. Departement van Landbouw, Nijverheid en Handel in Nederlandsch-Indië. 1953 pp. (3rd Edition, 1950. van Hoeve, 's-Gravenhage, the Netherlands / Bandung, Indonesia. 1660 pp.).
[27]Jumelle, H., 1903. Les plantes à caoutchouc et à gutta. Exploitation, culture et commerce dans tous les pays chauds [The rubber and gutta-producing plants. Exploitation, cultivation and trade in all warm countries]. A. Challamel, Paris, France. 543 pp.
[37]Rogers, D.J. & Appan, S.G., 1973. Manihot and Manihotoides (Euphorbiaceae). Flora Neotropica, Monograph 13. Hafner Press, New York, United States. 272 pp.
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[41]van Romburgh, P., 1899. Over caoutchouc-leverende boomen. 3. Manihot glaziovii Müll. Arg [On rubber-yielding trees. 3. Manihot glaziovii Müll. Arg]. Teysmannia 9: 245–252.
[42]van Romburgh, P., 1900. Caoutchouc en getah-pertja in Nederlandsch-Indië [Rubber and gutta-percha in the Dutch East Indies]. Mededeelingen uit 's Lands Plantentuin 39: 1–209.

E. Boer & P.C.M. Jansen

Boer, E. & Jansen, P.C.M., 2000. Manihot glaziovii Müll.Arg.. In: Boer, E. and Ella, A.B. (Editors): Plant Resources of South-East Asia No 18: Plants producing exudates. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea