Itsseed is the castor bean, which despite the term is not abean (as it is not the seed of a member of the familyFabaceae). Castor is indigenous to the southeasternMediterranean Basin,East Africa, andIndia, but is widespread throughout tropical regions (and widely grown elsewhere as an ornamental plant).
Castor seed is the source ofcastor oil, which has a wide variety of uses. The seeds contain between 40% and 60% oil that is rich intriglycerides, mainlyricinolein. Theseed also containsricin, a highly potentwater-soluble toxin.
Ricinus communis can vary greatly in its growth habit and appearance. The variability has been increased by breeders who have selected a range of cultivars for leaf and flower colours, and for oil production. It is a fast-growing,suckeringshrub that can reach the size of a small tree, around 12 metres (39 feet), but it is notcold hardy.
The glossyleaves are 15–45 centimetres (6–18 inches) long, long-stalked, alternate and palmate with five to twelve deep lobes with coarsely toothed segments. In some varieties they start off dark reddish purple or bronze when young, gradually changing to a dark green, sometimes with a reddish tinge, as they mature. The leaves of some other varieties are green practically from the beginning, whereas in yet others a pigment masks the green color of all thechlorophyll-bearing parts, leaves, stems and young fruit, so that they remain a dramatic purple-to-reddish-brown throughout the life of the plant. Plants with the dark leaves can be found growing next to those with green leaves, so there is most likely only a single gene controlling the production of the pigment in some varieties.[3] The stems and the spherical, spiny seed capsules also vary in pigmentation. The fruit capsules of some varieties are more showy than the flowers.
The flowers lack petals and are unisexual (male and female) where both types are borne on the same plant (monoecious) in terminalpanicle-likeinflorescences of green or, in some varieties, shades of red. The male flowers are numerous, yellowish-green with prominent creamystamens; the female flowers, borne at the tips of the spikes, lie within the immature spiny capsules, are relatively few in number and have prominent redstigmas.[4]
The fruit is a spiny, greenish (to reddish-purple)capsule containing large, oval, shiny, bean-like, highly poisonous seeds with variable brownish mottling. Castor seeds have a warty appendage called thecaruncle, which is a type ofelaiosome. The caruncle promotes the dispersal of the seed by ants (myrmecochory).
It reproduces with a mixed pollination system which favors selfing bygeitonogamy but at the same time can be an out-crosser byanemophily (wind pollination) orentomophily (insect pollination).[5]
Young plant
Green variant after blooming, with developing seed capsules
Leaf
Male flower
Pollen grains ofRicinus communis
Female flower
The green capsule dries and splits into three sections, forcibly ejecting seeds
Seeds
Cotyledons (round) and first true leaves (serrated) on a young plant (about four weeks old)
Threeterpenoids and atocopherol-related compound have been found in the aerial parts ofRicinus. Compounds named (3E,7Z,11E)-19-hydroxycasba-3,7,11-trien-5-one, 6α-hydroxy-10β-methoxy-7α,8α-epoxy-5-oxocasbane-20,10-olide, 15α-hydroxylup-20(29)-en-3-one, and (2R,4aR,8aR)-3,4,4a,8a-tetrahydro-4a-hydroxy-2,6,7,8a-tetramethyl-2-(4,8, 12-trimethyltridecyl)-2H-chromene-5,8-dione were isolated from the methanol extracts ofRicinus communis by chromatographic methods.[6]Partitioned h-hexane fraction ofRicinus root methanol extract resulted in enrichment of two triterpenes: lupeol and urs-6-ene-3,16-dione (erandone). Crude methanolic extract, enriched n-hexane fraction and isolates at doses 100 mg/kg p.o. exhibited significant (P < 0.001) anti-inflammatory activity in carrageenan-induced hind paw oedema model.[7]
Carl Linnaeus used the nameRicinus because it is aLatin word fortick; the seed is named so because of its bump at the tip as well as the markings borne that resemble certain ticks. The genusRicinus[9] also exists in zoology, and designates insects (not ticks) which are parasites of birds; this is possible because the names of animals and plants are governed by differentnomenclature codes.[10][11]
The common name "castor oil" probably comes from its use as a replacement forcastoreum, a perfume base made from the driedperineal glands of thebeaver (castor in Latin).[12] It has another common name,palm of Christ, orPalma Christi, that derives from castor oil's reputed ability to heal wounds and cure ailments.
AlthoughR. communis is indigenous to the southeasternMediterranean Basin,Eastern Africa, and India, today it is widespread throughout tropical regions.[13] In areas with a suitable climate, castor establishes itself easily where it can become an invasive plant and can often be found on wasteland.
Each castor seed has a yellow nodule full of fats one end of the seed that are nutritious for young ants. After hauling their harvest into their nests and pulling off the delicious part, ants discard the rest of the seed into their trash pile, where the future plant starts to grow.[15]
In Greece it is hardy enough to grow as a small tree. In northern countries it is grown instead as anannual.
It is also used extensively as a decorative plant in parks and other public areas, particularly as a "dot plant" in traditionalbedding schemes. If sown early, under glass, and kept at a temperature of around 20 °C (68 °F) until planted out, the castor oil plant can reach a height of 2–3 metres (6.6–9.8 ft) in a year. In areas prone tofrost it is usually shorter, and grown as if it were anannual.[13] However, it can grow well outdoors in cooler climates, at least in southern England, and the leaves do not appear to suffer frost damage in sheltered spots, where it remains evergreen.[16] It was used in Edwardian times in the parks of Toronto, Canada. Although not cultivated there, the plant grows wild in the US, notablyGriffith Park in Los Angeles.[17]
Cultivars have been developed by breeders for use as ornamental plants (heights refer to plants grown as annuals) and for commercial production of castor oil.[4]
'Hiruy' was developed by the Ethiopian Institute of Agricultural Research'sMelkassa andWondo Genet Agricultural Research Centers for hand harvest during 2010/2011
Ricinus is extremely allergenic, and has anOPALS allergy scale rating of 10 out of 10. The plant is also a very strong trigger for asthma, and allergies toRicinus are commonplace and severe.[21]
The castor oil plant produces abundant amounts of very light pollen, which easily become airborne and can be inhaled into the lungs, triggering allergic reactions. The sap of the plant causes skin rashes. People who are allergic to the plant can also develop rashes from touching the leaves, flowers, or seeds. They can also have cross-allergic reactions tolatex sap from the relatedHevea brasiliensis plant.[21]
The toxicity of raw castor beans is due to the presence ofricin. Although the lethal dose in adults is considered to be four to eight seeds, reports of actual poisoning are relatively rare.[22] According to theGuinness World Records, this is the world's most poisonous common plant.[23] Ricin is also present in lower concentrations throughout the plant.[citation needed]
If ricin is ingested, symptoms commonly begin within two to four hours, but may be delayed by up to 36 hours. These include a burning sensation in mouth and throat, abdominal pain, purging and bloody diarrhea. Within several days there is severe dehydration, a drop in blood pressure and a decrease in urine. Unless treated, death can be expected to occur within 3–5 days; however, in most cases a full recovery can be made.[24][25]
Poisoning occurs when animals, including humans, ingest broken castor beans or break theseed by chewing: intact seeds may pass through the digestive tract without releasing the toxin.[24] The toxin provides the castor oil plant with some degree of natural protection from insect pests such asaphids. Ricin has been investigated for its potential use as aninsecticide.[26]
Commercially available cold-pressed castor oil is not toxic to humans in normal doses, whether internal or external.[27]
Global castor seed production is around two million tons per year. Leading producing areas are India (with over three-quarters of the global yield), China and Mozambique, and it is widely grown as a crop in Ethiopia. There are several active breeding programmes.
No symbol = official figure, F = FAO estimate, * = Unofficial/Semi-official/mirror data, A = Aggregate (may include official, semi-official or estimates)
Other modern uses of natural, blended, or chemically altered castor products include:
As a non-freezing,antimicrobial, pressure-resistant lubricant for special purposes, either of latex or metals, or as a lubricating component of fuels.[28]
As attractively patterned, low-cost personal adornments, such as non-durable necklaces and bracelets. Holes must not be drilled in the beans to make beads. The outer shell protects the wearer from the poison. Wearing castor beans has been known to cause rashes, and worse.
As a component of many cosmetics.
As an anti-microbial. The high percentage ofricinoleic acid residues in castor oil and its derivatives, inhibits many microbes, whether viral, bacterial or fungal. They accordingly are useful components of many ointments and similar preparations.
Castor seeds have been found inEgyptian tombs dating back to 4000 BC; the slow-burning oil was mostly used to fuel lamps.Herodotus and otherGreek travellers noted the use of castor seed oil for lighting, body ointments, and improving hair growth and texture.Cleopatra is reputed to have used it to brighten the whites of her eyes. TheEbers Papyrus is an ancient Egyptian medical treatise believed to date from 1552 BC. Translated in 1872, it describes castor oil as alaxative.[30]
The use of castor bean oil (eranda) in India has been documented since 2000 BC in lamps and in local medicine as a laxative,purgative, andcathartic inUnani,Ayurvedic,siddha and otherethnomedical systems. Traditional Ayurvedic andsiddha medicine considers castor oil the king of medicinals for curingarthritic diseases. It is regularly given to children to treat infections with parasitic worms.[31]
The ancient Romans had a variety of medicinal/cosmetic uses for both the seeds and the leaves ofRicinus communis. The naturalistPliny the Elder cited the poisonous qualities of the seeds, but mentioned that they could be used to form wicks for oil lamps (possibly if crushed together), and the oil for use as a laxative and lamp oil.[32] He also recommends the use of the leaves as follows:
The leaves are applied topically with vinegar forerysipelas, and fresh-gathered, they are used by themselves for diseases of the mamillæ [breasts] and de- fluxions; a decoction of them in wine, withpolenta andsaffron, is good for inflammations of various kinds. Boiled by themselves, and applied to the face for three successive days, they improve the complexion.[33]
InHaiti it is calledmaskreti,[34] where the plant is turned into a red oil that is then given to newborns as apurgative to cleanse the insides of their first stools.[35]
Castor seed and its oil have also been used in China for centuries, mainly prescribed in local medicine for internal use or use in dressings.[36]
Castor oil was used as an instrument of coercion by the paramilitaryBlackshirts under the regime ofItalian dictatorBenito Mussolini and by theSpanish Civil Guard in Francoist Spain. Dissidents and regime opponents were forced to ingest the oil in large amounts, triggering severediarrhea anddehydration, which could ultimately cause death. This punishment method was originally thought of byGabriele D'Annunzio, the Italian poet and Fascist supporter, during theFirst World War.[37]
Castor oil is an effective motor lubricant and has been used ininternal combustion engines, including those ofWorld War I airplanes, some racing cars and somemodel airplanes. It has historically been popular for lubricatingtwo-stroke engines due to high resistance to heat compared to petroleum-based oils. It does not mix well with petroleum products, particularly at low temperatures, but mixes better with the methanol-based fuels used inglow model engines. Intotal-loss-lubrication applications, it tends to leave carbon deposits and varnish within the engine. It has been largely replaced by synthetic oils that are more stable and less toxic.
Jewellery can be made of castor beans, particularly necklaces and bracelets.[39] Holes must not be drilled into the castor beans as the shell protects the wearer from the ricin.[citation needed] Any chips in the shell can cause poisoning of the wearer.[citation needed] Pets who chew the jewellery can become ill.[39]
Ricinus communis leaves are used in botanical printing (also known as ecoprinting) in Asia. When bundled with cotton or silk fabric and steamed, the leaves can produce a green-colored imprint.[40][better source needed]
^"Ricinus communis: Castor oil plant".Oxford University Herbaria. Dept. of Plant Sciences, Oxford.The castor oil plant is one of the few major crops to have an origin in Africa.
^Oliver, Paul M.; Lee, Michael S.Y. (2010). "The botanical and zoological codes impede biodiversity research by discouraging publication of unnamed new species".Taxon.59 (4):1201–1205.Bibcode:2010Taxon..59.1201O.doi:10.1002/tax.594020.ISSN0040-0262.
^abcPhillips, Roger; Rix, Martyn (1999).Annuals and Biennials. London: Macmillan. p. 106.ISBN978-0-333-74889-3.
^Cross, Fiona R., and Robert R. Jackson. "Odour‐mediated response to plants by evarcha culicivora, a blood‐feeding jumping spider from East Africa." New Zealand Journal of Zoology 36.2 (2009): 75-80.
^Guinness World Records 2017. London, UK: Guinness World Records Limited. 2016. p. 43.
^abSoto-Blanco B, Sinhorini IL, Gorniak SL, Schumaher-Henrique B (June 2002). "Ricinus communis cake poisoning in a dog".Vet Hum Toxicol.44 (3):155–6.PMID12046967.
^Irwin R (March 1982). "NTP technical report on the toxicity studies of Castor Oil (CAS No. 8001-79-4) In F344/N Rats And B6C3F1 Mice (Dosed Feed Studies)".Toxic Rep Ser.12: 1–B5.PMID12209174.
^Rekha, D. (2013). "Study of medicinal plants used from koothanoallur and marakkadai, Thiruvarur district of Tamil Nadu, India".Hygeia Journal for Drugs and Medicines.5 (1):164–170.
^Petersen, Jens (1982), "Violence in Italian Fascism, 1919–25",Social Protest, Violence and Terror in Nineteenth- and Twentieth-century Europe, London: Palgrave Macmillan UK, pp. 275–299,doi:10.1007/978-1-349-16941-2_17,ISBN978-1-349-16943-6
^Zahir AA, Rahuman AA, Bagavan A, et al. (August 2010). "Evaluation of botanical extracts againstHaemaphysalis bispinosa Neumann andHippobosca maculata Leach".Parasitology Research.107 (3):585–92.doi:10.1007/s00436-010-1898-7.PMID20467752.S2CID20498642.
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