Castorbean is a shrub or small tree originating in tropical Africa and now widely distributed and cultivated for the oil in its seed, which has a range of industrial uses.
It is fast-growing, herbaceous when young, with age becoming woody and forms either a shrub or tree depending on the variety. Some trees reach heights of up to 12 m (40 ft), though between 3 and 5 m (10 and 16 ft) is more common. In tree form, the trunk is slender with smooth grey-white or light-brown bark and supports a rounded crown with a moderate number of large leaves.
Leaves large, from 30 to 60 cm (1 to 2 ft) wide and star-shaped with seven to nine serrate, pointed lobes. These emerge bronze, gradually become green with age, or wine-red in some varieties, and attach to the branches with a long hollow leaf stalk.
Flowers unisexual, small, greenish and borne on conical flower spikes 15 to 60 cm (0.5 to 2 ft) long, the male flowers situated below the females. These bloom on and off throughout the year but are at their fullest from spring to summer and are followed by burr-like seed capsules, blue-green or red when young, turning brown when mature with three brown or black mottled seed inside. When fully mature, the seed capsule bursts open scattering the seed.
Castorbean comes in many varieties, differing in plant size, foliage colour, seed capsule size, as well as seed size, shape and colour.
The seed yield on cold pressing a colourless to pale yellow, viscid oil known as 'Castor oil' or 'Palma Christi oil'. On hot pressing, the oil is brown to near black. Ricin, a highly toxic protein poisonous to humans and animals is present in the seed but is not passed to the pressed oil.
Oil yields are around 35 to 60% of the seed by weight. The leftover seedcake contains about 5% nitrogen, 2% phosphate and 1% potash and is mostly used to fertilise crops. It can also be fed to livestock if it is first heat treated to destroy the ricin.
Castor oil has application in the lubricant, biofuel, chemical, textile, cosmetic, pharmaceutical, surface coating, and soap-making industries.
The oil maintains a constant viscosity at high temperatures making it a suitable lubricant, hydraulic fluid and brake fluid for machinery and moving parts operating under various temperature and pressure conditions. It has reportedly been successfully engine-tested as a Biodiesel.
Castor oil is commercially processed into Polyamide 11, a thermoplastic in the nylon family of polymers. Polyamide 11, also known as Nylon 11 is used in high-pressure hoses (particularly those used in the oil and gas industry), automotive tubing, electrical cables, textiles, footwear, as well as metal coatings (for noise reduction and to protect against corrosion).
The oil also has plasticizing properties, which promotes plasticity, flexibility and reduces brittleness in materials. This has led to it being used in plastics to make them more malleable or mouldable and in resins to make surface coatings, which can range from paint or varnish to nail polish. In the cosmetic industry, it is used in face- or peeling-masks, shaving cream, bath oils, hair-grooming products, lipstick and nail polish removers. In the confectionery industry, it is used as an anti-sticking coating and release agent in hard candy, and in pharmaceuticals as a protective coating in pills.
Soap with castor oil has increased lathering power, is highly soluble in cold water, and owing to its exceptional clarity, is used in making transparent soaps.
It has been estimated that more than half of all lipstick sold in the United States contains castor oil as an ingredient.
In India, Castor oil is prescribed for nervous disorders and it is well known for its strong laxative and purgative action, particularly in the treatment of food poisoning as well as in excavating the bowel before X-ray examination.
The flower clusters are highly susceptible to fungal disease brought on by humid conditions. Castorbean grows naturally and is most productive in sub-humid to moderately humid subtropical and tropical climates, generally in frost-free areas with annual lows of 15 to 25 °C, annual highs of 26 to 36 °C, annual rainfall of 700 to 2000 mm and a dry season of 3 to 7 months.
Castorbean is also grown with irrigation in low rainfall areas with a long dry season. In fact, it is cultivated with irrigation in the Indian states of Gujarat and Rajasthan, in areas receiving only 300 mm annual rainfall and with a long dry season lasting up to 9 months.
New plants are usually started from seed, which germinate readily. Performance is best on friable, free-draining loam and sand soils of a moderately acid to alkaline nature, generally with a pH of 5 to 8 and on sites with full to partial sun exposure.
Sowing is in the rainy season and is timed so that flowering occurs at the start of the dry season, thereby minimising the risk of fungal attack.
Castorbean takes from four to seven months to mature after sowing, with the seed-capsules harvested when they become yellowish, which is when they are ripe but not fully mature. They are then left in shallow piles in the sun to dry, which takes about four to five days.
The seed contain ricin, a poison that is extremely toxic to humans and livestock.
Castorbean trees bear seed profusely and these are scattered when the seed capsule bursts open. It is recorded as an invasive species in more than one country and is assessed as a high weed risk species for Hawaii and South Florida, respectively by the Hawaii Pacific Weed Risk Assessment project (HPWRA) and the IFAS Assessment of Non-Native Plants in Florida's Natural Areas.
Pollen produced by the male flowers is known to cause hay fever in some people.
Adams, C. D. 1972, Flowering plants of Jamaica, University of the West Indies, Mona, Greater Kingston
Brady, G. S. & Clauser, H. R & Vaccari, J. A. 2002, Materials handbook : an encyclopedia for managers, technical professionals, purchasing and production managers, technicians and supervisors, 15th ed., McGraw-Hill, New York
Chevallier, A. 2000, Encyclopedia of herbal medicine, 2nd American ed., Dorling Kindersley, New York
Duke, J. A. 1983, Handbook of energy crops (unpublished), Center for New Crops & Plants Products, Purdue University, West Lafayette, Indiana
Fawcett, W. 1891, Economic plants, An index to economic products of the vegetable kingdom in Jamaica, Jamaica Government Printing Establishment, Kingston
Francis, J. K. 2004, Wildland shrubs of the United States and its territories: Thamnic descriptions, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, Río Piedras, San Juan, Puerto Rico & Rocky Mountain Research Station, Fort Collins, Colorodo
Gohl, B. 1981, Tropical feeds : feed information summaries and nutritive values (Revised edition), Food and Agriculture Organization of the United Nations (FAO), Rome
Gunstone, F. D. 2011, Vegetable oils in food technology : composition, properties and uses, 2nd ed, Wiley-Blackwell, Hoboken, New Jersey
Jelks, Mary 1986, Allergy plants : that cause sneezing and wheezing, 1st ed., World-Wide Publications, Tampa, Florida
Khan, I. A. & Abourashed, E. A. 2010, Leung's encyclopedia of common natural ingredients : used in food, drugs and cosmetics, 3rd edition, Wiley Publishing, Hoboken, New Jersey
Litzenberger, S. C. 1974, Guide for field crops in the tropics and the subtropics, Office of Agriculture, Technical Assistance Bureau, Agency for International Development (USAID), Washington D.C.
Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London
McIlroy, R.J. 1963, An introduction to tropical cash crops, Ibadan University Press, Ibadan, Nigeria
Mors, W. B & Rizzini, C. T. 1966, Useful plants of Brazil, Holden-Day Publishing, San Francisco, California
Morton, J. F. 1971, Exotic plants, Golden Press, New York
Oakman, H. 1995, Harry Oakman's what flowers when : the complete guide to flowering times in tropical and subtropical gardens, University of Queensland Press, St. Lucia, Queensland
Parrotta, J. A. 2001, Healing plants of peninsular India, CABI Publishing, Wallingford, Oxfordshire
Perry, F. & Hay, R. 1982, A field guide to tropical and subtropical plants, Van Nostrand Reinhold Company, New York
Selvam, V. 2007, Trees and shrubs of the Maldives, Food and Agriculture Organisation (FAO) RAP publication (Maldives), Thammada Press Company Ltd., Bangkok
Smith, F. G. 2003, Beekeeping in the tropics, Northern Bee Books, Hebden Bridge, West Yorkshire
van der Vossen, H.A.M. & Mkamilo, G.S. (Editors) 2007, Plant Resources of Tropical Africa, Volume 14 : Vegetable oils, PROTA Foundation, Backhuys Publishers, Leiden
Winter, R. 2009, A consumer's dictionary of cosmetic ingredients : complete information about the harmful and desirable ingredients found in cosmetics and cosmeceuticals, 7th ed, Three Rivers Press, New York
Buddenhagen C.E., Chimera C. & Clifford P. 2009, Assessing Biofuel Crop Invasiveness: A Case Study, PLoS ONE 4
Johnson, A. & Johnson, S. 2006, Garden plants poisonous to people, New South Wales Department of Primary Industries (NSW DPI), Orange, New South Wales
Morton, J.F. 1964, Honeybee Plants of South Florida, Proceedings of the Florida State Horticultural Society, Vol 77:415-436.
Queensland Department of Agriculture and Fisheries (Australia) 1990, Weed and pest animal fact sheets, Brisbane
This website is provided for general information only. Iplantz makes no statements, representations or warranties as to the accuracy or completeness of the content of this website and does not accept any liability to you or any other person for the information which is provided or referred to on this website.
In particular, Iplantz does not represent or warrant that any dataset or the data it contains is accurate, authentic or complete, or suitable for your needs. Changes in circumstances after the time of publication may impact the accuracy of datasets and their contents.
To the maximum extent permitted by law, Iplantz accepts no liability whatsoever to any person arising from or connected with the use of or reliance on any information or advice provided on this website or incorporated into it by reference, including any dataset or data it contains. No responsibility is taken for any information or services that may appear on any linked websites.