Ricinus communis (Castor bean)


The castor bean plant, Ricinus communis, is a "native of tropical Africa cultivated in several varieties for the oil found in its leaves and for its bold foliage."(Alber and Alber)

The "stalked leaves consist of usually eight radiating, pointed leaflets with slightly serrated edges and prominent central veins. Many varieties are green, but some are reddish brown."(Cooper and Johnson) The flowers are green and inconspicuous, but pink or red in the pigmented varieties. Many stamens are near the base and branching pistils are near the top of the flower. The soft-spined fruits containing attractively mottled seeds are distinctive features of the plant.

It is grown as an ornamental in gardens, sometimes as a houseplant, and also grows as a weed.
It is an annual in the south and a perennial in the tropics, and it may reach "15 feet tall outdoors".
It is a woody herb belonging to the family of Euphorbiacea (Spurge).

For further details on the plantís characteristics, see "Poisonous Plants Page, Ricinus Communis, http://res.agr.ca./

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Castor bean poisoning


The seeds from the castor bean plant, Ricinus communis, are poisonous to people, animals and insects. One of the main toxic proteins is "ricin", named by Stillmark in 1888 when he tested the beansí extract on red blood cells and saw them agglutinate. Now we know that the agglutination was due to another toxin that was also present, called RCA (Ricinus communis agglutinin). Ricin is a potent cytotoxin but a weak hemagglutinin, whereas RCA is a weak cytotoxin and a powerful hemagglutinin.

Poisoning by ingestion of the castor bean is due to ricin, not RCA, because RCA does not penetrate the intestinal wall, and does not affect red blood cells unless given intravenously. If RCA is injected into the blood, it will cause the red blood cells to agglutinate and burst by hemolysis.

Perhaps just one milligram of ricin can kill an adult.

The symptoms of human poisoning begin within a few hours of ingestion.

The symptoms are:

Within several days there is:

If death has not occurred in 3-5 days, the victim usually recovers.


It is advisable to keep children away from the castor bean plant or necklaces made with its seeds. In fact donít even have them in or around a house with small children. If they ingest the leaves or swallow the seeds, they may get poisoned. The highly toxic seeds beaded into necklaces, cause skin irritation at the contact point.

If the seed is swallowed without chewing, and there is no damage to the seed coat, it will most likely pass harmlessly through the digestive tract. However, if it is chewed or broken and then swallowed, the ricin toxin will be absorbed by the intestines.

It is said that just one seed can kill a child. Children are more sensitive than adults to fluid loss due to vomiting and diarrhea, and can quickly become severely dehydrated and die.

Castor bean plants in a garden should not be allowed to flower and seed. A good practice is to "nip it in the bud".


In 1978, ricin was used to assassinate Georgi Markov in 1978, a Bulgarian journalist who spoke out against the Bulgarian government. He was stabbed with the point of an umbrella while waiting at a bus stop near Waterloo Station in London. They found a perforated metallic pellet embedded in his leg that had presumably contained the ricin toxin.


Aphids, drawn above on a leaf of the castor bean plant, are susceptible to poisoning from ingesting the phloem. The sap-suckers died within 24 hours of feeding.

The European corn borer and the Southern corn rootworm larvae were killed when exposed to feed painted with 2% ricin. Studies like these are undertaken to develop "natural" pesticides.

Castor beans are used as an ingredient in some animal feeds after the oil has been extracted or inactivated by heating for 20 minutes at 140oC. Attempts to use castor beans in feed for livestock involve different methods of inactivating ricin while maintaining nutritional value. Some studies have shown that even afte such heat treatment, toxicity remains. For example, it was lethal to mallard ducks given the feed. "The toxicity of the meal could be due to either a heat stable or growth inhibiting factor or due to minute residues of ricin"(Okoye et al.)
A study with sheepshowed that autoclaved castor-bean-meal can be incorporated to 10% of sheep rations without any ill effect.

Poisoning of livestock usually occurs by accidental incorporation of castor beans in their feed. Horses are particularly vulnerable.

For more detailed information about effects of Ricin on livestock, see... "Poisonous Plants Page, Ricinus Communis, http://res.agr.ca./

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Castor oil

Castor beans are pressed to extract castor oil which is used for medicinal purposes. Ricin does not partition into the oil because it is water-soluble, therefore, castor oil does not contain ricin, provided that no cross-contamination occurred during its production.

More information describing this plant is available under the listing for Ricinus communis, Castor Bean, in the Canadian Poisonous Plants Information System, courtesy of Derek B. Munro.

See also: Castoroil.in - a complete reference of all things caster.

[Index][Castor bean plant] [Castor bean poisoning][Castor bean oil] [More about ricin toxin from castor beans]

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