|Castor oil plant|
|Castor bean in disturbed area|
The castor oil plant, Ricinus communis, is a species of flowering plant in the spurge family, Euphorbiaceae. It belongs to a monotypic genus, Ricinus, and subtribe, Ricininae. The evolution of castor and its relation to other species is currently being studied.
Its seed is the castor bean which, despite its name, is not a true bean. Castor is indigenous to the southeastern Mediterranean Basin, Eastern Africa, and India, but is widespread throughout tropical regions (and widely grown elsewhere as an ornamental plant).
Castor seed is the source of castor oil, which has a wide variety of uses. The seeds contain between 40% and 60% oil that is rich in triglycerides, mainly ricinolein. The seed contains ricin, a toxin, which is also present in lower concentrations throughout the plant.
Another plant species, Fatsia japonica, is similar in appearance and is known as the false castor oil plant.
Although monotypic, the castor oil plant can vary greatly in its growth habit and appearance. It is a fast-growing, suckering perennial shrub which can reach the size of a small tree (around 12 metres/39 feet), but it is not cold hardy.
The glossy leaves are 15–45 centimetres (5.9–18 in) long, long-stalked, alternate and palmate with 5–12 deep lobes with coarsely toothed segments. Their colour varies from dark green, sometimes with a reddish tinge, to dark reddish purple or bronze. The stems (and the spherical, spiny seed pods) also vary in pigmentation. The pods are more showy than the flowers.
The flowers are borne in terminal panicle-like inflorescences of green monoecious flowers without petals. The male flowers are yellowish-green with prominent creamy stamens and are carried in ovoid spikes up to 15 centimetres (5.9 in) long; the female flowers, born at the tips of the spikes, have prominent red stigmas).
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 the caruncle, which is a type of elaiosome. The caruncle promotes the dispersal of the seed by ants (myrmecochory).
The name Ricinus is a Latin word for tick; the seed is so named because it has markings and a bump at the end which resemble certain ticks. The common name "castor oil" probably comes from its use as a replacement for castoreum, a perfume base made from the dried perineal glands of the beaver (castor in Latin). It has another common name, palm of Christ, or Palma Christi, that derives from castor oil's ability to heal wounds and cure ailments.
Although castor is indigenous to the southeastern Mediterranean Basin, Eastern Africa, and India, today it is widespread throughout tropical regions. In areas with a suitable climate, castor establishes itself easily as an apparently "native" plant and can often be found on wasteland.
It is also used extensively as a decorative plant in parks and other public areas, particularly as a "dot plant" in traditional bedding 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 to frost it is usually shorter, and grown as if it were an annual. 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. It was used in Edwardian times in the parks of Toronto, Ontario, Canada.
Selections have been made by breeders for use as ornamental plants (heights refer to plants grown as annuals)
(all the above grow to around 1.5 metres (4.9 ft) tall as annuals)
Ricinus communis is the host plant of the Common Castor butterfly (Ariadne merione), the Eri silkmoth (Samia cynthia ricini), and the Castor Semi-Looper moth (Achaea janata). It is also used as a food plant by the larvae of some other species of Lepidoptera, including Hypercompe hambletoni and the Nutmeg (Discestra trifolii).
The toxicity of raw castor beans due to the presence of ricin is well-known. Although the lethal dose in adults is considered to be 4 to 8 seeds, reports of actual poisoning are relatively rare.. According to the 2007 edition of the Guinness Book of World Records, this plant is the most poisonous in the world.
Poisoning occurs when animals ingest broken seeds or break the seed by chewing: intact seeds may pass through the digestive tract without releasing the toxin. Toxicity varies among animal species: 4 seeds will kill a rabbit, 5 a sheep, 6 an ox or horse, 7 a pig, 11 a dog, but it takes 80 to kill a duck. The toxin provides the castor oil plant with some degree of natural protection from insect pests, such as aphids. In fact, ricin has been investigated for its potential use as an insecticide. It is also the source for undecylenic acid, a natural fungicide.
Global castor seed production is around 1 million tons per year.
Leading producing areas are India (with over 60% of the global yield), China and Brazil, and it is widely grown as a crop in Ethiopia. There are several
active breeding programmes.
|Top ten castor oil seed producers — 11 June 2008|
|People's Republic of China||210000||*|
|No symbol = official figure,
P = official figure, F = FAO estimate, * =
Unofficial/Semi-official/mirror data, C = Calculated figure A =
Aggregate (may include official, semi-official or estimates);
In Brazil, castor oil (locally known as mamona oil) is now being used to produce biodiesel. In rural areas, the abundant seeds are used by children for slingshot balls, as they have the right weight, size, and hardness.
The attractive castor seeds are used in jewelry, mainly necklaces and bracelets. This practice bears is highly dangerous, due to the extreme toxicity of the seeds, especially if the seedcoat is drilled for stringing.
Castor seeds have been found in Egyptian tombs dating back to 4000 BC; the slow burning oil was used mostly to fuel lamps. Herodotus and other Greek travelers 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. The Ebers Papyrus is an ancient Egyptian medical treatise believed to date from 1552 BC. Translated in 1872, it describes castor oil as a laxative.
The use of castor bean oil in India has been documented since 2000 BC in lamps and in local medicine as a laxative, purgative, and cathartic in Unani, Ayurvedic and other ethnomedical systems. Traditional Ayurvedic medicine considers castor oil the king of medicinals for curing arthritic diseases.
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.
It was used in rituals of sacrifice to please the gods in early civilizations.
Castor oil is known to have been used as an instrument of coercion by the paramilitary Blackshirts under the regime of Italian dictator Benito Mussolini. Dissidents and regime opponents were forced to ingest the oil in large amounts, triggering severe diarrhoea and dehydration, which could ultimately cause death. This punishment method was originally thought of by Gabriele D'Annunzio, the Italian poet and Fascist supporter, during the First World War. (See also: Castor oil: Use as a means of intimidation in Fascist Italy)
Ricinus communis, pollen (scanning electron microscope image)
Ricinus communis, seed
Ricinus communis, fruit
Seedling showing prominent cotyledons
Ricinus communis, flowers and fruit
Ricinus communis "Carmencita" in a garden in the Netherlands
Ricinus communis, fruit and leaf, Cornell Plantations 2008
Classification System: APG II (down to family level)
Cladus: core eudicots
Cladus: Eurosids I
Species: Ricinus communis
Ricinus communis L.
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