Pictures of castor bean plants

Castor bean is an exotic addition to the garden.

With oversized, tropical-looking leaves and bizarre seed pods, castor bean is an exotic addition to the ornamental garden. The only member of the genus, Ricinus communis is in the Spurge Family (Euphorbiaceae). The word ricinus is Latin for “tick”, used for this plant name because of the superficial resemblance of the seeds to a particular species of European tick. Castor bean is native to tropical east Africa around Ethiopia, but has naturalized in tropical and subtropical areas around the world to become a weed in many places, including the southwestern U.S. Plants are typically found in moist, well-drained soils in disturbed areas, such as along river beds and roadsides, and in fallow fields or at the edges of cultivated lands.

Castor bean is a fast-growing tender perennial large shrub or small tree.

Castor bean is an evergreen herbaceous or semi-woody large shrub or small tree. This robust tender perennial can grow to 40 feet tall, developing woody stems over a few years in frost-free climates. Because of its rapid, vigorous growth, it is easily grown as a warm season annual in temperate climates, but it rarely exceeds 6-10 feet in a single growing season. This fast growing plant tends to grow straight up at first, developing branches later in the season to form a well-proportioned shrub with sturdy stems and a dense canopy. The plant is killed when the temperature drops below 32F. Unlike many members of the euphorbia family, this plant does not have milky latex sap, but has a watery sap.

The large palmate leaves have many deeply
incised lobes.

The alternate, star-shaped leaves on long petioles can grow over 2½ feet across. Each palmate leaf has 5 to11 deeply incised lobes, with serrated edges and prominent central veins. The species has glossy green leaves, but cultivated selections may have black-purplish, dark red-metallic, bronze-green, or maroon leaves, or bright green leaves with white veins.

Flowers are produced in dense inflorescences 8-18″ tall at the tops of the stems. The monoecious plants produce male flowers below the terminal female flowers. The flowers do not have petals and are not particularly showy. The ½ inch male flowers each have a cluster of many cream or yellow stamens that shed large amounts of wind-borne pollen. They senesce soon after shedding their pollen. The three conspicuous, star-shaped stigma lobes of the female flowers are bright red with feathery branches.

The small male flowers are produced below the more conspicuous terminal female flowers.

The little spiny ovary of the female flower develops into a fruit or seed capsule about the size of a golf ball after pollination. The seed pods may be green, pink, or red (depending on the variety), but gradually age to brown. Each spherical, seed capsule is thickly covered with soft flexible spines and has three sections that separate when the seeds are mature. Each section contains one seed that is ejected, often with considerable force, when the carpel splits open.

The spiny seed pods may be green (L), pink or red (C), but eventually turn brown and split open when ripe (R).

The ½ inch long seeds, or “beans” (they are not true beans), are produced in large numbers where the growing season is long enough (140 to 180 days). The shiny, intricately mottled seeds are quite attractive, each with their own unique design in colors of black, gray, brown, yellow-brown, maroon and white.

The intricately mottled seeds have a
spongy caruncle at one end.

Each seed has a small, spongy caruncle at one end which helps absorb water for germination when planted. Seeds remain viable for 2-3 years. About half the weight of the seed is a thick, yellowish or almost colorless oil that has been used in many industrial applications. The oil was used in ancient times as fuel for lamps, and is now used in paints and varnishes, for water-resistant coatings, in high-performance motor oils, soap, inks, and plastics. Other derivatives are used in polishes, as solid lubricants, in synthetic perfumes and other products. Plants are grown commercially for oil production primarily in India and Brazil, but also in some parts of the U.S. and other countries.

The seeds are extremely poisonous, so keep plants out of reach of children (or trim off flowering spike if this is a concern). The toxin in castor seeds is ricin (RYE-sin), one of the deadliest natural poisons, estimated as 6,000 times more poisonous than cyanide and 12,000 times more poisonous than rattlesnake venom. As few as four seeds can kill an average-sized adult, while ingestion of lesser amounts will result in vomiting, severe abdominal pain, diarrhea, and convulsions. Livestock and poultry can also be affected if they consume seeds or meal from the seeds. Although it is a very potent poison, ricin has been investigated as an anti-cancer agent. Ricin is water soluble, not lipid (oil) soluble, so it is not released during the pressing process, remaining in the leftover “seed cake.” This residue is used as a high-nitrogen fertilizer, or after detoxicating, the meal can be used as livestock feed. Since the toxin does not occur in the pure oil, castor oil can be consumed and has been used medicinally as a remedy for everything from constipation to heartburn. It is an effective cathartic or purgative (laxative) and can be used externally as an emollient for dry skin.

Castor bean is often grown as an ornamental.

When grown as an ornamental, castor bean can be planted directly in the garden in late spring, or started indoors earlier (6-8 weeks before the average last frost) and transplanted outdoors when the weather warms. Nick or scarify the seeds or soak overnight for better germination. Sow the seeds 1-1½ inches deep. Seedlings should start coming up in 1-3 weeks. The young plants grow quite quickly and may need repotting into larger containers before transplanting outdoors. Place the plants outdoors in full sun and deep, rich soil about 4 feet apart. Provide plenty of water and fertilizer to achieve the largest size. Once established it can tolerate drought. Wind can shred the leaves, so they should be placed in a protected spot if possible. Plants can be pruned to limit the size, or may need staking if top heavy; otherwise this plant needs very little maintenance. Castor bean has few pests, although spider mites can sometimes be a problem in hot, dry weather.

The large seeds germinate in 1-3 weeks (L) with smooth cotyledons (C) that do not resemble the true leaves that are soon produced on the seedlings (R).

The large leaves and unusual seed
pods make castor bean a dramatic
addition to the ornamental garden.

With its large leaves and tall stature, castor bean makes a bold statement in the garden. The coarse texture contrasts well with finely textured plants. Grow castor bean as a specimen for a dramatic focal point in the landscape, or in groups for a tropical effect in the back of beds or near water features. It can be used to create a temporary screen or informal hedge or can be grown in large containers on patios. Castor bean combines well with cannas, bananas and elephant ears for a tropical garden. Or use it as a backdrop for grasses and other large-scaled annuals for a more traditional look.

A range of varieties have been selected for their leaf or flower/fruit colors, and for oil production. Some of the most common ornamental types include:

  • There are many cultivars of castor bean, with
    ornamental types selected for different leaf
    color and plant height.

    ‘Carmencita Bright Red’ – has red stems and bright red seed pods, along with dark purplish or bronzy-red leaves. This well-branched cultivar grows about 5-6 feet tall.

  • ‘Carmencita Pink’ – has pinkish-red stems and seed pods.
  • ‘Carmencita Rose’ – has blue-green foliage and peach-colored seed pods.
  • ‘Gibsonii’ – with dark red-tinged leaves and pinkish seed pods, it grows 4-5 feet tall.
  • ‘Impala’ – a more compact cultivar that grows to 4 feet tall with reddish-purple leaves and stems, with the brightest color on the new growth.
  • ‘New Zealand purple’ – has smaller, reddish purple leaves and branches less than other types.
  • ‘Red Spire’ – grows 7-10 feet tall, with red stems, bronze leaves, and red seed pods.
  • ‘Sanguineus’ – has blood-red stems and leaves.
  • ‘Zanzibarensis’ – another tall variety (7-10 feet) with green leaves with white midribs.

– Susan Mahr, University of Wisconsin – Madison

Childrens 02.10.2019 admin 1 Comment

How to dispose of castor bean plants

All parts of the castor bean plant are poisonous. The University of California Cooperative Extension recommends that you not use poisonous. The castor bean is a type of annual grass. Learn about growing, propagating, and using castor beans at HowStuffWorks. I’m sure many of you are pretty familiar with castor oil. Read the following article to know more about its source, the castor bean plant, and.

Castor bean plants (Ricinus communis) contain toxic compounds that can be deadly to wildlife, pets Clean the pot with bleach and dispose of it in a trash bag. I’m sure many of you are pretty familiar with castor oil. Read the following article to know more about its source, the castor bean plant, and. EARLY last summer, at an herb festival in Maryland, I stumbled on a four-inch castor bean plant. As I admired its purplish-green, red-veined.

Q. I have a question about a plant that I find very intriguing: the Castor Bean Plant . I had seen a few in my neighborhood and finally tracked a plant down in. I have several Castor bean plants. How do I dispose of them in the fall? I have my own black plastic compost bins, and also use a yard. All parts of the castor bean plant are poisonous. The University of California Cooperative Extension recommends that you not use poisonous.

Q: A friend of mine gave me some seeds of castor bean. I understand the plant is very poisonous but it is beautiful and I would like to grow it. In some areas of the world, castor bean plants are invasive. But here in Minnesota, they make beautiful and unique tropical plants that die back every fall (funny. With oversized, tropical-looking leaves and bizarre seed pods, castor bean is an exotic addition to the ornamental garden. The only member of.

Department of Animal Science – Plants Poisonous to Livestock

Ricin Toxin from Castor Bean Plant, Ricinus communis

Ricin is one of the most poisonous naturally occuring substances known.

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 beans’ 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:

  1. abdominal pain
  2. vomiting
  3. diarrhea, sometimes bloody.

Within several days there is:

  1. severe dehydration,
  2. a decrease in urine,
  3. and a decrease in blood pressure.

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.

Castor Bean Plant, Poisoning, and Oil

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).

Castor bean poisoning – Children

It is advisable to keep children away from the castor bean plant or necklaces made with its seeds. In fact don’t 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 to the right 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 sheep showed 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.

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 them is available under the listing for Castor Bean, in the Canadian Poisonous Plants Information System, courtesy of Derek B. Munro.

Mechanism of Toxic Action

Many cytotoxic proteins from a variety of plants have been identified, and they are related to ricin both in structure and function. They inhibit protein sythesis by specifically and irreversibly inactivating eukaryotic ribosomes.

These “ribosome-inactivating proteins” (RIPs) are typically N-glycosylated, 30 kDa monomers (Type 1 RIPs). However, in order to bind to the cell surface galactosides and enter the cytosol to reach ribosomes, they require a second monomer, a galactose-binding, 30 kDa lectin. The monomers are joined by a disulfide bridge to form the toxic heterodimers (Type 2 RIPs).

Some plants, such as wheat andbarley, have only Type 1 RIPs, and are not poisonous, while others, such as the castor bean plant seed, contain the Type 2 RIPs that are among the most potent cytotoxins in nature. 5% of the Ricinus seed consists of ricin and RCA (Ricinus communis agglutinin).

Ricin is a heterodimeric type 2 RIP. This ribosome-inactivating enzyme (32 kDa), also known as the A chain, is linked by a disulfide bond to the galactose/N-acetylgalactosamine-binding lectin (34 kDa), also called the B chain.

Ricin Biosynthesis

Ricin and RCA are synthesized in the endosperm cells of maturing seeds, and are stored in an organelle called the “protein body”, a vacuolar compartment. When the mature seed germinates, the toxins are destroyed by hydrolysis within a few days.

Ricin begins sythesis as a prepropolypeptide that contains both A and B chains. The signal sequence of the Nh3-terminus targets the nascent chain to the endoplasmic reticulum (ER) and is then cleaved off. As the proricin polypeptide elongates it is N-glycosylated within the lumen of the ER. Protein disulfide isomerases catalyze disulfide bond formation as the proricin molecule folds itself. Proricin undergoes further oligosaccharide modifications within the Golgi complex and then is transported within vesicles to the protein bodies.

Ricin is not catalytically active until it is proteolytically cleaved by an endopeptidase within the protein bodies. This splits the polypeptide into the A chain and the B chain still linked by a single disulfide bond. Since ricin is inactive until then, the plant avoids poisoning its own ribosomes in case some proricin accidentally passes into the cytosol during synthesis and transport.

Ricin Enzymatic Action

The ricin A portion of the heterodimer is the enzyme that binds and depurinates a specific adenine of the 28S rRNA. The adenine ring of the ribosome becomes sandwiched between two tyrosine rings in the catalytic cleft of the enzyme and is hydrolyzed by the enzymeís N-glycosidase action. The target adenine is a specific RNA sequence that contains the unusual tetranucleotide loop, GAGA. Ricin is more active against animal than plant ribosomes, and intact bacterial ribosomes are generally not susceptible.

Ricin Structure

This figure from Lord et al, depicts a 3-dimensional ribbon drawing of ricin, modeled from X-ray crystallography data. The upper right half, the dotted ribbon, is the A chain, and the lower left half, the solid ribbon, is the B chain.

The A chain (or RTA)is a 267-amino acid globular protein. It has 8 alpha helices and 8 beta sheets. The substrate binding site is the cleft marked by the substrate adenine ring.

The B chain (or RTB) is a 262-amino acid protein that is shaped like a barbell. It has a binding site for galactose at each end, (depicted by lactose rings). These two sites allow hydrogen bonding to specific membrane sugars (galactose and N-acetyl galactosamine). A disulfide bridge (-S-S-) joins RTA with RTB (far-right, center). The spheres are trapped water molecules.

Ricin Uptake

The RTB portion of ricin binds to both glycoproteins and glycolipids at cell surfaces that terminate with galactose. It has two binding sites for galactose, and 106 to 108 ricin molecules may bind per cell. However, just a single ricin molecule that enters the cytosol can inactivate over 1,500 ribosomes per minute and kill the cell.

As shown in the diagram, the pathway for internalization of ricin involves:

  1. endocytosis by coated pits and vesicles or,
  2. endocytosos by smooth pits and vesicles. The vesicles fuse with an endosome.
  3. Many ricin molecules are returned to the cell surface by exocytosis, or
  4. the vesicles may fuse to lysosomes where the ricin would be destroyed.
  5. If the ricin-containing vesicles fuse to the Trans Golgi Network, (TGN), thereís still a chance they may
  6. return to the cell surface.
  7. Toxic action will occur when RTA, aided by RTB, penetrates the TGN membrane and is liberated into the cytosol.

Once inside the cytosol, the RTA catalyzes the depurination of the ribosomes, halting protein synthesis.

Therapeutic Applications of Immunotoxins

Ricin can be targeted to specific cells, such as cancer cells, by conjugating the RTA subunit to antibodies or growth factors that preferentially bind the unwanted cells. These immunotoxins have worked very well for in vitro applications, e.g. bone marrow transplants. Although they have not worked very well in many in vivo situations, progress in this area of research shows promise for the future.


In bone marrow transplant procedures, RTA-immunotoxins have been used successfully to destroy T lymphocytes in bone marrow taken from histocompatible donors. This reduces rejection of the donor bone marrow, a problem called “graft-vs-host disease” (GVHD). In steroid-resistant, acute GVDH situations, RTA-immunotoxins helped alleviate the condition. Also, in autologous bone marrow transplantation, a sample of the patients own bone marrow is treated with anti-T cell immunotoxins to destroy malignant T-cells in T cell leukemias and lymphomas.


“For the in vivo treatment of solid tumors, considerable problems can arise due to poor access of the immunotoxin (IT) to the tumor mass; lack of IT specificity, tumor cell heterogeneity, antigen shedding, breakdown or rapid clearance of the IT, and dose-limiting side effects”. (Lord et al.). One common problem encountered in patients treated with ricin-immunotoxins is the “vascular leak syndrome”, in which fluids leak from blood vessels leading to hypoalbuminemia, weight gain and pulmonary edema. “Research efforts to expand and develop immunotoxins and therapies for clinical use in cancer and AIDS are continuing with strategies utilizing recombinant DNA technology (Lord et al.).

Toxigenic Ablation


“Toxigenes are DNA fusions in which DNA encoding a potent toxin, e.g. RTA, is placed under the transcriptional control of a tissue- or developmental stage-specific promoter and/or enhancer. When expressed intracellularly, the toxigene product causes cell death. The introduction and expression of a toxigene in transgenic animals or plants may lead to cell type-specific ablation, which can be used to

  • study developmental cell lineages or to
  • generate animal models of degenerative diseases.” (Lord et al.)

Suicide Transport

Diagram shows injection of ricin into vagal nerve and subsequent destruction of neurons (dashed neurons destroyed, solid neurons unaffected).

Neuroscientists can selectively destroy neurons by injecting ricin into nerves. Retrograde axonal transport mechanisms bring the toxin to the neuronal cell bodies where the ribosomes are localized.

Ultrastructural analysis reveals that ricin first causes the dispersion of polyribosomes, and then the rough endoplasmic reticulum disorganizes into smooth vesicles. The cell bodies (perikaryon) swell, the nuclei degenerate and the entire neuron disintegrates.

Since ricin is a N-acetyl galactosamine-binding lectin, it can be used with different lectins that have different specificities tomap neuronal patterns of glycosylation. When suicide transport is observed after injection of the toxin, it confirms the presence of N-acetyl galactosamine residues on the neuronal cell surface. Strategies in suicide transport work very well in studies of adult peripheral sensory and motor neurons because they are sensitive to ricin.

Neurons in the central nervous system of adults are resistant to ablation by ricin, whereas young developing brains are sensitive, suggesting that brain development involves changes in glycosylation of CNS neurons. The galactose terminal residues may be either clipped or masked by addition of sialic acids residues.

In suicide transport experiments, often some ricin leaks out of the nerve, causing systemic poisoning of the animal. This problem can be avoided by simultaneously administering a ricin antiserum.

The value of using suicide transport strategies is summarized (from Wiley and Oeltmann):

  • anatomical mapping of neurons
  • modeling of motor neuron degenerative diseases
  • studying consequences of peripheral nerve damage and repair mechanisms
  • mapping cellular neurotransmitter receptors
  • disease-related applications including
    • eradication of latent herpes simplex virus in trigeminal sensory neurons
    • production and analysis of glial fibrillary bundles
    • treatment of equine neuromas

Frankel, A.E., (1993) Immunotoxin Therapy of Cancer. Oncology (Huntington), 7(5):69-78; discussion79-80, 83-6.

Knight, B. (1979) Ricin-a potent homicidal poison. Br. Med. J. 278:350-351.

Lord, J.M., Roberts, L.M., and J.D. Robertus. (1994). FASEB J. Feb; 8(2):201-8.

Matthews, R.W., and J.R. Matthews (1978). Insect Behavior, pub. Wiley and Sons, Inc. New York, pp.507.

Robertus, J.D. (1988). Toxin Structure. Cancer Treat. Res. 37:11-24.

Robertus, J. D. (1991) The structure and action of ricin, a cytotoxic N-glycosidase. Sem. in Cell Biol. 2:23-30.

Vitetta, E.S. and P.E. Thorpe, (1991) Immunotoxins containing ricin or its A chain, Sem. in Cell Biol. 2:47-58.

Q: A friend of mine gave me some seeds of castor bean. I understand the plant is very poisonous but it is beautiful and I would like to grow it. Someone else told me it might be illegal to grow. Your advice on all of this and how to grow it, please? – Betsy W. – Clay, AL

A: Castor bean, or castor oil plant, is indeed a stately, striking and beautiful plant in the garden, with a bold texture and a tall, upright form unlike most other plants. Selected varieties have red (reddish) leaves and flowers, but the species is green, often with good red or purple-brown coloration on new growth and stems. We grow a red form in the Ireland Iris Garden here at Birmingham Botanical Gardens.

The leaves and especially the seeds of the plant contain the powerful toxin ricin and for that reason it is one of the most poisonous plants in the world: if you eat a half-dozen seeds and do not get medical treatment (which, obviously, I do not recommend) it can be fatal. Growing the plant as an ornamental or a crop is not illegal, but extracting and concentrating ricin from it is, as you would in effect be making a potent biological weapon (obviously, I do not recommend that, either). Please read on for a full explanation.

Known as Ricinus communis , castor bean is not a true bean. Beans are also called legumes and are in the Fabaceae. Castor bean is in the spurge family, Euphorbiaceae. Originally native to the southeastern Mediterranean, east Africa and India, it is now common throughout the tropics and has been cultivated for centuries as an ornamental and medicinal plant. It is the source of castor oil, so called because it was a replacement for castoreum, a perfume base extracted from the dried pineal gland of beavers (Castor sp.).

A much older common name for castor bean is Palm of Christ (Latin: Palma Christi), which refers to the palm-shaped leaf and the plant’s various purported medicinal or healing properties (which are interesting, but beyond the scope of this article to discuss). One source I checked mentioned that 600-800 million pounds of castor oil are used globally each year in the making of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals and perfumes. In the US, food-grade castor oil is a recognized safe ingredient in food, and is used in flavorings and candy, as a mold inhibitor, and in packaging. Of course, many will remember castor oil’s widespread use in times past as a general laxative (although not a gentle one). For all such uses, ricin is chemically removed from the seeds.

In our area, castor bean can be easily grown as a summer annual in most soils that are not permanently wet, preferably in full, but light shade is acceptable. It does not require but responds well to fertilization and grows quickly in our summer heat and humidity. The flowers are fuzzy little clusters borne on centrally-located, cone-shaped structures. They are interesting but not highly ornamental as they are often hidden by the bold and colorful foliage (see image). Our plants have self-seeded on their own for a number of years after planting, pretty much in place or nearby, and usually reach 5-7′ in height by the time they are killed by a hard frost. In the tropics they form woody shrubs or small trees. The seeds, which look like spotted, swollen ticks (Ricinus derives from the Greek word for tick) can be harvested (carefully, see below!) in the fall, stored in the fridge, and grown in pots starting in late winter, to be planted in the garden after the last frost. If I had some seeds right now, I would probably plant half and store half (again, in the fridge) for next spring. That way if the ones planted this year failed to mature enough to flower (and make more seed), I’d still have some seed for next season.

As mentioned, this plant is potentially very toxic. Any part of it, at any stage of its life cycle, must be handled with some care. Do not attempt to make your own castor oil at home, or use the plant to make folk medicine, or do anything with it other than look at it!

In the garden, danger from castor bean is not specifically from occasionally handling the plant, but from ingesting plant parts, namely the leaves and, especially, the seeds, which contain the greatest concentration of ricin. Clearly, ingesting (eating) the non-food plants you garden with as ornamentals is not part of a normal gardening routine, so you’d really have to go out of your way to do this, or you’d just have to be careless.

It is a very good practice to wash your hands thoroughly after gardening and before eating (or drinking) anyway, and doubly so if gardening with plants that are known to be toxic. And – surprise – many plants (including such common plants as yews, daffofils and azaleas) are toxic if you eat them, so it is a good idea to treat all ornamental plants as potentially harmful if eaten. Wearing gloves – and regularly washing them, too – is also a good idea.

So eat your herbs and vegetables and don’t eat your ornamentals! Wash thoroughly after handling castor bean leaves and seeds and you will be fine. Interestingly, a source I checked indicated that humans will pass unbroken castor bean seeds without incident as our gut does not digest or otherwise break the seed coat and expose the ricin. But just take their word on it and do not try this!

The Euphorbiaceae is infamous as a number of its members produce substances that are toxic to humans (and other animals). Typically, the toxin is in the milk-colored sap which, in the presence of ultraviolet light (such as in sunlight), causes contact dermatitis in most individuals. This effect is termed phytophotodermatitis and the symptoms include darkening of the skin (may look like a bruise) and blistering and/or burning (and perhaps nausea). Symptoms may be quite painful and last three days or more. The sap may also cause blindness, generally of the temporary kind, but permanent eye damage can result. This is the primary danger from the popular holiday plant (and castor bean cousin) poinsettia, although a small percentage of people have an allergic reaction to the foliage as well (not as bad as poison ivy). There is virtually no danger to pets or humans from accidental ingestion of poinsettia leaves; one source mentioned that an adult would have to eat about 500 of them to suffer any negative impacts at all.

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Garden Myths – Learn the truth about gardening

I was giving a talk at a local Master Gardner meeting the other day and I mentioned that castor beans contain one of the world’s most deadly organic compounds. Someone in the audience commented that you can actually eat several castor beans and you would only get a mild stomach ache.

These two points of view seem to contradict one another. What is the real story?

Castor beans, Ricinus communis

Deadly Caster Bean

The caster bean plant, Ricinus communis, is a native of tropical Africa and is grown in many gardens in North America for its fabulous large leaves. Here in zone 5 it is an annual that can grow to 5 feet in one season.

The caster bean plant itself is not poisonous to humans, but the seeds are. The seeds contain a protein called ricin and there is no question that ricin is very poisonous to humans, animals and even insects.

The caster bean holds the Guinness Book of World Records title for the world’s most poisonous plant, due to Ricin. Several lists of the poisonous chemicals exist on the internet and ricin is in the top ten list most of the time. Its position on any given list depends on how the list is defined. Does the list look at all chemicals or just naturally occurring ones? Is it looking at the caster bean or pure ricin? The details are not important; but the conclusion is clear – ricin is one of the most deadly naturally occurring chemicals. It is also more deadly than most man-made chemicals.

It is reported that as few as 5 beans is enough to kill an adult human. Fewer beans will kill a child.

Are the Castor Beans Really Poisonous?

Would it surprise you that you can eat a handful of beans and have no effect from them?

The skin of the bean is quite firm and thick. If you swallow the castor bean whole, it will travel through your system intact. No ricin will enter your body. To release the ricin into your system you must chew the beans before swallowing them.

So I guess you could argue that the beans are not really poisonous so long as you don’t chew them. It then follows that you will not be poisoned by just handling the beans–a common gardening myth.

Is Castor Bean Oil Poisonous?

The oil extracted from castor beans does not contain ricin and therefore is not poisonous.

Can a Castor Bean be Used to Murder Someone?

The actual bean is probably not a good weapon, but poisoning by ricin has been documented. For some interesting reading have a look at the death of Georgi Ivanov Markov – sounds like it would make a good movie.

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The castor oil plant (Ricinus communis L), is a plant species of the family Euphorbiaceae and the sole member of the genus Ricinus and of the subtribe Ricininae.1 The castor plant is native to the Ethiopian region of east Africa. It grows in tropical and warm temperate regions throughout the world and is becoming an abundant weed in the southwestern United States. Ricinus communis is a perennial, erect, branched, herb, typically less than 2 meters in height.2 The beans are oblong and light brown, mottled with dark brown spots. The seed is only toxic if the outer shell is broken or chewed. Ricin is contained in the bean pulp following the separation of the oil from the beans. No ricin is thought to remain in the oil, and it is inactivated during extraction if done under heated conditions.

Ingested castor beans are generally toxic only if the ricin is released through mastication. Reports on the ricin content of castor beans vary, but it is probably in the range of 1% to 5%.3 Purified ricin is a white powder that is soluble in water and stable over a wide pH range.4

It is a protein toxin (toxalbumin).5 It is a glycoprotein lectin composed of 2 chains, A and B, linked by a disulfide bond.6 The B chain is a lectin and binds to galactose-containing glycoproteins and glycolipids expressed on the surface of cells, facilitating the entry of ricin into the cytosol.7 The A chain inhibits protein synthesis by irreversibly inactivating eukaryotic ribosomes through removal of a single adenine residue from the 28S ribosomal RNA loop contained within the 60S subunit. This process prevents chain elongation of polypeptides and leads to cell death.8

Toxicity results from the inhibition of protein synthesis, but other mechanisms are noted including apoptosis pathways, direct cell membrane damage, alteration of membrane structure and function, and release of cytokine inflammatory mediators.9

The castor bean plant also contains another glycoprotein lectin, the Ricin communis agglutinin, which, unlike ricin, is not directly cytotoxic, but does have affinity for the red blood cell, leading to agglutination and subsequent haemolysis. Ricin communis agglutinin is not significantly absorbed from the gut and causes clinically significant haemolysis only after intravenous administration.10

There are no literature reports of poisoning from ingesting purified ricin. All clinical reports with regard to poisoning refer to castor bean ingestion. Documented mild to lethal clinical symptoms may result from ingesting one half to 30 beans.11 Two castor oil beans were the minimum number found to be associated with death.12 Symptom onset after ingestion is usually within 4 to 6 hours but may be as late as 10 hours.13 Initial symptoms are nonspecific and may include colicky abdominal pain, vomiting, diarrhoea, heartburn, and oropharyngeal pain. Haematemesis and melena are reported less commonly.14 Fluid losses may lead to electrolyte imbalances, dehydration, hypotension, and circulatory collapse.15 Laboratory abnormalities may include leukocytosis, elevated transaminases and creatinine kinase, hyperbilirubinemia, renal insufficiency, and anaemia.16 Information on allergic reactions to ricin is primarily from persons working in or living near castor bean processing plants.17 Allergy patch testing reveals an IgE–mediated inflammatory reaction to ricin although other allergens may be present in the castor bean dust.18

Castor beans have been used traditionally by women in many countries for birth control.19 The use of castor seed oil in India has been documented since 2000 BC for use in lamps and in local medicine as a laxative, purgative, and cathartic in Unani, Ayurvedic and other ethnomedical systems. Castor seed and urine have also been used in China for centuries, mainly prescribed in local medicine for internal use or use in dressings.1

Castor beans have been found in ancient Egyptian tombs dating back to 4000 B.C. According to the Ebers Papyrus, an Egyptian medical text from 1500 BC, Egyptian doctors used castor oil to protect the eyes from irritation. The oil from the bean was used thousands of years ago in facial oils and in wick lamps for lighting.20 In Oman, this is the first patient we have receive in the last 10 years who used castor beans as a traditional treatment for a cough.

Castor Bean Plant Stock Photos and Images

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  • Leaves red flowers of Castor Bean plant, Ricinus Communis var Carmencita, Euphorbiaceae, above
  • Castor bean and Cerbera odollam seed for decoration
  • Castor oil seeds
  • Castor oil plant and seed on white background
  • A Castor bean plant in a garden (Ricinus communis Zanzibarensis). Ricin de Zanzibar dans un jardin.
  • Close-up Of Castor Bean Plant
  • Castor Bean Plant ‘ricinus communis’
  • Castor Bean Plant
  • Castor bean plant on La Palma
  • An ornamental castor oil plant or castor bean seeding in a public garden in St Emilion, France, August
  • Castor Bean/ Castor oil plant (Ricinus communis)
  • Ricinus communis,Castor-oil plant or Castor bean plant or Ricinus plant. Oklahoma City, Oklahoma, USA.
  • Medicinal plant Rizinus communis Rhizinus blossoms of the castor bean plant
  • Castor Bean Plant (Ricinis)
  • Flowering Castor Bean plant grown in Monticello garden.
  • Castor Oil co ltd lubricating oil, Applying, Body Part, Bottle, Business Finance and Industry, Can, Canned Food, Cartoon, Castor Bean Plant,
  • castor oil plant, central-franconia, bavaria, germany, (Ricinus communis)
  • Pink Castor Bean Plant Close-Up
  • Castor Bean
  • Leaves red flowers of Castor Bean plant, Ricinus Communis var Carmencita, Euphorbiaceae
  • Selective focus on prickly fruits of wild castor oil plant (Ricinus communis) with Canary Island spurge in background (Tenerife, Spain)
  • Branch of ricinus communis or castor bean plant with red spherical spiny seed capsules
  • Ricinus communis, the castor bean, or castor oil plant
  • castor bean seed pods, Ricinus communis
  • castor oil plant ‘Carmencita’
  • Biodiesel is produced from the seed pods of castor bean plants
  • Castor bean plant on La Palma
  • Fruit of the Castor Oil Plant ‘Ricinus Communis’ ‘Castor Bean’ plant growing in a garden in the Loire, France in August
  • Castor Bean/ Castor oil plant seeds (Ricinus communis)
  • Ricinus communis,Castor-oil plant or Castor bean plant or Ricinus plant. Oklahoma City, Oklahoma, USA.
  • Landscape with castor bean plant closeup
  • Castor Bean Plant (Ricinis)
  • Flowering Castor Bean plant grown in Monticello garden.
  • Castor Oil co ltd lubricating oil, Applying, Body Part, Bottle, Business Finance and Industry, Can, Canned Food, Cartoon, Castor Bean Plant,
  • Female flowers of castorbean / castor-oil-plant (Ricinus communis) indigenous to the Mediterranean, Eastern Africa and India
  • Castor bean and Cerbera odollam seed for decoration
  • castor bean or castor oil plant
  • Leaves red flowers of Castor Bean plant, Ricinus Communis var Carmencita, Euphorbiaceae, above
  • Castor bean plant, castor oil plant, Ricinus communis
  • Perennial garden flower border plant Castor Bean, Ricinus communis flowers
  • castor-oil plant, castor oil plant, ricin, Castor bean, Castorbean (Ricinus communis), young fruit
  • Flowers and seeds on a castor oil plant isolated on white background
  • young castor bean seed pods
  • castor oil plant ‘Carmencita’
  • Biodiesel is produced from the seed pods of castor bean plants
  • Castor bean plant on La Palma
  • Fruit of the Castor Oil Plant ‘Ricinus Communis’ ‘Castor Bean’ plant growing in a garden in the Loire, France in August
  • Castor Bean/ Castor oil plant seeds (Ricinus communis)
  • Castor whitefly Trialeurodes ricini eggs and scales crawlers larvae pupae on castor
  • Ricinus communis, the castor oil plant
  • Castor Bean Plant (Ricinis)
  • Castor bean plant.
  • Ricinus communis Castor Bean flower
  • Close-up Of Castor Bean Flowers
  • Fantastic glossy leaf of castor bean tree also called castor oil plant or ricinus communis ,bright red and green color in a sunny day
  • castor bean or castor oil plant, Wunderbaum oder Rizinus, ricinus, Ricinus communis
  • Leaves and red fruits of castor bean or castor oil plant Euphorbiaceae Ricinus communis
  • Wild castor oil plant (Ricinus communis) growing on Tenerife island (Spain)
  • A close up macro image of the leaf of a castor bean begonia.
  • castor-oil plant, castor oil plant, ricin, Castor bean, Castorbean (Ricinus communis), young fruit
  • Seeds on a castor oil plant close up isolated on white background
  • young castor bean seed pods
  • castor oil plant ‘Carmencita’
  • castor bean or castor oil plant (Ricinus communis), Inflorescence with male and female flowers
  • Female flowers of castorbean / castor-oil-plant (Ricinus communis) indigenous to the Mediterranean, Eastern Africa and India
  • Fruit of the Castor Oil Plant ‘Ricinus Communis’ ‘Castor Bean’ plant growing in a garden in the Loire, France in August
  • The seed capsules of a castor oil plant (Ricinus communis)
  • Vertical frame of a Ricinus (Ricinus communis ,or ‘castor oil plant’), a poisonous plant
  • ‘Impala’ Castor oil plant, Ricin (Ricinus communis)
  • Castor Bean
  • Castor bean plant.
  • Castor Bean (Ricinus communis), Euphorbiaceae.
  • Castor Plant in Agriculture field
  • Castor bean on white background , extreme close-up
  • the red blossom from a Ricinus communis, the castor bean or castor-oil-plant
  • Red spherical spiny seed capsules of castor bean also called castor oil plant or ricinus communis , red fruits against a bright sky ,
  • Prickly fruits of wild castor oil plant (Ricinus communis) in front of orange rock face (Tenerife, Spain)
  • A close up macro image of the stem of a castor bean begonia.
  • castor-oil plant, castor oil plant, ricin, Castor bean, Castorbean (Ricinus communis), infructescence
  • Seeds of a castor oil plant isolated on white background
  • young castor bean seed pods
  • castor oil plant ‘Carmencita’
  • castor bean
  • Castorbean / castor-oil-plant (Ricinus communis) indigenous to the southeastern Mediterranean Basin, Eastern Africa and India
  • Capsules of castor oil plant (Ricinus communis), red variant, a tropical plant which seeds / beans are used to produce castor oil.
  • Green castor beans with essential oil
  • castor plant with flower and leaves
  • ‘Impala’ Castor oil plant, Ricin (Ricinus communis)
  • Castor Bean
  • Close up of a blooming castor oil plant (ricinus communis) with red flower balls
  • Castor Bean (Ricinus communis), Euphorbiaceae.
  • Castor Plant in Agriculture field
  • Castor oil plant (Ricinus communis) in fruit
  • the red blossom from a Ricinus communis, the castor bean or castor-oil-plant
  • Fantastic glossy leaves of castor bean tree also called castor oil plant or ricinus communis ,bright red , yellow and green color in a sunny day
  • Castor oil plant (Ricinus communis ‘Carmencita’). Leaves, stems and fruits. Sedgwick Gardens on Long Hill estate, in Beverly, MA
  • Castor oil seeds
  • castor-oil plant, castor oil plant, ricin, Castor bean, Castorbean (Ricinus communis), fruiting
  • Castor tree,ricinus communis, with fruits

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Should You Grow the Castor Bean Plant?

Q. I have a question about a plant that I find very intriguing: the Castor Bean Plant. I had seen a few in my neighborhood and finally tracked a plant down in nearby Ottsville, PA, thinking I’d hit the jackpot. I planted it in a spot I thought it would like judging from the others I’d seen, and it has thrived right outside my back door. Then I read an article about the plant in my favorite local paper, The Bucks County Herald, and was horrified! The described toxicity of the beans (though they are beautiful to look at) really scared me! I had known nothing about the beans being poisonous; I just loved the way the plant looked and how it added contrast to the garden.

I had just passed on some seeds to my Mom, and as soon as I finished the article I called her to say “Don’t touch them again until I talk to Mike McGrath!” I even had anxiety dreams about it, as we have four children, a beloved dog, and this plant is right outside our back door. The children are ages 6 to 12, so they know better than to ingest a bean, and the dog doesn’t go into my garden that often. Am I over-reacting to think I should I rip this specimen out of the ground and have my Mom toss the seeds? Seeing the word ‘Ricin’ in the article literally scared me silly. My mom and I would love to hear your thoughts on this, and we always appreciate your words of wisdom and humor.

    —Gayle in Doylestown, PA

A. Ah yes—the dreaded, deadly castor bean plant!

Let’s begin with what it is—a dramatic tropical plant that can easily grow ten feet tall in a season with huge colorful leaves as big as dinner plates. Because it is tropical, Gayle doesn’t have to worry about the one she planted, as it died from frost shortly after she wrote us back in October. (In frost free climes they can become small trees.)

The plant has a surprisingly long history, with Lawrence Griffith’s fine book “Flowers and Herbs of Early America” (published by the Colonial Williamsburg Foundation in 2008 in association with the Yale University Press) citing references to it as far back as the third century BC. Early Egyptians apparently used oil pressed from the notorious seeds in their lamps, and Thomas Jefferson is known to have deliberately planted it in areas where he hoped it would live up to its folklore and deter moles. (And, true to his famously competitive nature, he carefully nurtured one show-off specimen to a height of 22 feet.)

Unfortunately Jefferson probably learned that making George Washington extremely jealous was pretty much all the plant would do, as it seems to be universally acknowledged that a castor bean plant growing in soil does not deter moles. But some studies suggest that a specific form of castor oil distilled from the beans does repel moles, voles and other underground pests when applied to the soil. (As with medicinal castor oil, the poisonous ricin is removed during the distillation process.)

And yes, it really is ricin in the beans—the same deadly poison used in a famous political assassination involving a trick umbrella and in numerous terrorist incidents.

So, has Gayle endangered her mother by sending her those Seeds of Death (which look, by the way, like beautifully-colored engorged dog ticks)? Nope. I found the seeds listed for sale in several 2012 catalogs—all with the warning to keep the seeds away from children, but otherwise touted as a dramatic tropical ornamental(especially some of the subspecies, which sport wildly colored leaves).

The seeds are perfectly safe to handle, as they have a heavy protective coating that must be broken to release any of the nasty bits. Some sources even say that you could swallow the seeds without ill effect as they would simply pass through you, and that you’d have to chew them to be poisoned. (We do not suggest putting this advice to the test.)

Dr. Gerald Klingaman, retired horticulturist for the University of Arkansas Extension in Little Rock (and a frequent guest on our show), once named the castor bean his ‘plant of the week’, ( and called it a great choice for garden mavericks who like big, bold statements. He noted that while the toxicity of the beans was well established, he could find no reports of any ill effects from accidental poisonings—only use of the active ingredient in murder plots.

Since many of the worries I hear gardeners express are about the possibility of small children being ‘castorized’, I called the world-renowned Children’s Hospital of Philadelphia and was put in touch with Dr. Kevin Osterhoudt, Medical Director of their Poison Control Center, Attending Physician in their Division of Emergency Medicine, and editor of “Pick Your Poison”, a great feature that appears in the journal Pediatric Emergency Care, in which physicians send in case reports of kids who show up in the emergency room after ingesting something and you, the reader, try and guess what it was from their symptoms. (The culprit is frequently a plant part, and so we will definitely try and get this guy on our show in the future!)

Dr. Osterhoudt was kind enough to send us the details of the four children who had been rushed to Children’s after ingesting castor beans in the last ten years. The age range of the inquisitive youngsters was tight—all were between 15 and 24 months of age, and all four were suspected of ingesting a single bean. None of the four experienced any symptoms, despite two of them having chewed the beans!

In a follow-up phone call, Dr. Osterhoudt stressed that these happy outcomes should not be seen as a sign of safety. More beans or more susceptible children might have led to different consequences, he notes; and even children who show no immediate symptoms should be monitored for potential future liver problems.

But does Philadelphia speak for the nation, I wondered? So I also contacted the American Association of Poison Control Centers, who kindly searched their data base and reported that poison information centers around the nation received 110 calls about “exposure to castor beans” in 2010, but that there were “no major effects” reported as a result of those exposures. (Dr. Osterhoudt included the 2009 national data with his information, and it was strikingly similar—212 ‘exposures’ with no major toxicity.)

An official (can you tell by now that I used to be a medical reporter?) notes that there have been cases of livestock poisoning (the beans are used as an ingredient in ‘feed cakes’ and apparently the manufacturing process can go badly wrong) in addition to the well-known implication of the bean’s ricin in terrorist and murder plots. Then they offer what may be the best piece of advice for those who want to grow this striking specimen without worry—don’t let the plants set seed. If you’re concerned about the seeds, pull off all the flowers as they form, pull off immature seeds as they form and just enjoy the massive leaves.

As we’ve always stressed on the show, teach children not to eat strange things, and don’t grow plants with poisonous parts if you have small children or dogs that seem to chew on everything.

Otherwise, plant the seeds directly in the ground after all risk of frost is gone, in rich, well-drained soil, and see if you can beat Jefferson’s twenty-two footer.

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Scientific name

Ricinus communis (Castor Oil Plant)

Ricinus communisL.


Ricinus africanus Willd., Ricinus angulatus Thunb., Ricinus armatus Haw., Ricinus badius Rchb., Ricinus chinensis Thunb., Ricinus digitatus Noronha , Ricinus europaeus T.Nees, Ricinus glaucus Hoffmanns., Ricinus hybridus Besser, Ricinus inermis Mill., Ricinus japonicus Thunb., Ricinus laevis DC., Ricinus leucocarpus Bertol., Ricinus lividus Jacq., Ricinus macrophyllus Bertol., Ricinus medicus Forssk., Ricinus megalospermus Delile, Ricinus minor Mill., Ricinus nanus Balbis, Ricinus peltatus Noronha, Ricinus purpurascens Bertol., Ricinus rugosus Mill., Ricinus sanguineus Groenland, Ricinus scaber Bertol. ex Moris, Ricinus speciosus Burm.f., Ricinus spectabilis Blume, Ricinus tunisensis Desf., Ricinus undulatus Besser, Ricinus urens Mill., Ricinus viridis Willd., Ricinus vulgaris Mill.

Common names

Castor oil plant, castor-bean, palma-christi, mbarika (Kiswahili), ol-dule (Maasai), nsogasoga (Luganda)




This species probably originated in Africa, but is now widespread throughout the tropical and subtropical regions of the world.

Naturalised distribution (global)

Locations within which Ricinus communis is naturalised include Australia, USA, Mexico, South America, New Zealand and many oceanic islands with warm climates.

Introduced, naturalised or invasive in East Africa


Disturbed areas, roadsides, riverbanks.


Ricinus communis is a long-lived (perennial) shrub with can grow to the size of a small tree in suitable conditions.

R. communis can vary greatly in its growth habit and appearance (Sabina et al. 2009). 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, suckering perennial shrub which can reach the size of a small tree (around 12 metres tall), but it is not cold hardy.

The glossy leaves are 15-45 cm long, long-stalked, alternate and palmate with 5-12 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 start, whereas in yet others a pigment masks the green colour of all the chlorophyll-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 probably is only a single gene controlling the production of the pigment in some varieties at least. 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 are borne in terminal panicle-like inflorescences of green or, in some varieties, shades of red monoecious flowers without petals. The male flowers are yellowish-green with prominent creamy stamens and are carried in ovoid spikes up to 15 cm 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).

Reproduction and dispersal

Ricinus communis reproduces by seed with plants becoming mature in their first season. They are capable of flowering year round in a frost-free environment. The plant can seed prolifically. Seeds can be dispersed by rodents and birds, on mud adhering to boots, on vehicles and machinery and by floodwaters. It is also spread by an explosive mechanism (at local level) when the capsule dries up and splits. Taller plants can throw their seeds 5-plus metres from the mother tree.

Economic and other uses

Ricinin which can be extracted from the beans of castor oil is highly toxic and has been used in homicide. Castor oil has more benign uses as a soap and as vehicles or carriers, emollients or solubilisers for toiletries and cosmetics and are used for cleansing and conditioning the skin. The plant has medicinal properties. It is gaining popularity as a biodiesel crop.

Environmental and other impacts

Ricinus communis forms monospecific stands which can displace native plant species. It can invade neglected farmland and pasture. The seeds are poisonous if they are chewed and ingested. Seeds that are not chewed are likely to be harmless. The foliage is only slightly toxic.

R. communis has been listed as a noxious weed in the Australian states of New South Wales and the Northern Territories and as a Category 2 invader in South Africa (invaders with certain qualities, e.g. commercial use or for woodlots, animal fodder, soil stabilisation, etc. These plants are allowed in certain areas under controlled conditions).


The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Ricinus communis can be controlled through cultivation and mowing or physical uprooting. Herbicides can be effective as cut stump treatments or basal bark applications (painting herbicide onto the bark).

When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert. Fire can be used as a management tool, but usually in combination with other methods such as chaining. Fire alone may actually increase R. communis densities by plant regrowth and enhanced seed germination.

The editors do not know of any biological control programmes targeted at this species.


Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.


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 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. 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 (“eranda”) 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 (Kalaiselvi et al. 2003).

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 civilisations (Joshi et al. 2004)

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.

Global Invasive Species Database online data sheet. Ricinus communis. Accessed March 2011.

Henderson, L. (2001). Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa. Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.


Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat – UK.


This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) – Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).


BioNET-EAFRINET Regional Coordinator: [email protected]

Castor bean plant
(Ricinus communis)

You have probably seen this exotic plant before, it is gorgeous with its large, boldly coloured leaves, but look out – it is the highly toxic Castor bean plant (Ricinus communis).

Gardening Spain tips tricks Mediterranean

The genus name, Ricinus means “dog tick” in Latin, because that is what the seeds look like.

The Castor bean was originally native to northeastern Africa and the Middle East, but has gone wild and naturalized almost everywhere in the world that has a tropical or subtropical climate and is especially common in coastal areas.

Castor bean grows wild on rocky hillsides, waste lands, fallow fields, along road shoulders and at the edges of cultivated lands.
Ricinus communis


About Castor bean

Castor bean is a Euphorbia (Spurge) family member and like many Euphorbias it is poisonous, has highly caustic sap, and produces extremely allergenic pollen.

There are several cultivated varieties with strikingly different foliage colourations, including black-purplish, dark red-metallic, bronze-green, maroon, bright green with white veins, and just plain green.

In cold climates it is an annual, growing quickly, setting many seeds, and dying off in winter.

In mild winter areas, like ours, it is a long-lived perennial, sometimes reaching small tree size. Each plant produces hundreds of the bean-like seeds and these seeds can remain viable for more than a decade.

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Castor bean is very easy to grow – too easy, some might say.

They have a tendency to self sow and new seedlings can pop up all summer long.

This is one of the fastest growing plants in the world and becomes almost treelike in 3-4 months.

Going native

Castor bean plant spreads quickly because it has many built-in advantages over native plants.

A very robust grower, its leaves are poisonous even to predatory insects. Aphids that can safely feed on many other poisonous plants quickly die after sucking the juice of castor bean leaves.

But castor bean has one disadvantage. It is completely easy to recognize and can then be killed by chopping it down or spraying it with herbicides.

Ricinus communis castor bean plant


Deadly seeds
Castor plant is beautiful, but the castor bean seeds contain ricin, one of the most poisonous naturally occurring chemicals known to man. Even very small doses can be fatal.

I guess most of you know the story of the assassination of Georgi Markov, a dissident Bulgarian journalist. He died mysteriously while waiting for a bus near Waterloo Station in London, in 1978.

The Scotland Yard postmortem revealed that Markov was murdered, shot in the leg with an umbrella rigged as a pellet gun. The perforated metallic pellet stuck in his leg was found to contain the deadly ricin toxin.
There is a great deal of concern about castor plants in gardens. The entire plant is toxic, but the beans particularly so. In light of the fact that just one milligram of ricin will kill an adult, it is best to leave castor bean seeds alone.

An old-time practice was to nip off castor flowers to prevent seed production since the leaves are what most appeal to gardeners. castor-Fatsia-japonica
Ricinus communis

Positive features

The toxic seeds, however, also have many positive uses: Castor oil, derived from castor beans, is used extensively in medicine and in varnishes and paints, as a lubricant and lamp oil, and in many other industrial and manufacturing processes.

The foul tasting laxative, castor oil, loathed by children everywhere, tastes poisonous but is a valuable purgative still widely used in modern medicine.

Castor oil also is used externally to treat some kinds of skin diseases including ringworms and warts.

The seeds are also toxic to gophers. Old-time gardeners used to drop beans into the rodents’ holes to poison them. The planting of Castor bean plants around the perimeter of a garden was another way to discourage the pests.

The seeds have long been an important source of oil famous for retaining viscosity at very high temperatures and is a major ingredient for Castrol racing oil.
Ricinus communis Flower

In the landscape

Castor is an extraordinary plant right in style with today’s foliage-centered gardens.

The huge leaves are as suited to a Victorian garden as they are to modern tropical inspired looks. And if you follow the old practice of snipping off the flower stalks before seeds form, the plants are nearly risk-free.

Most gardeners grow Castor bean plants in small groups as specimen plants to create a tropical look.

This is a large, coarse textured plant that grows very fast in a single season to fill in a big area or serve as temporary landscaping or quick screening. In frost free areas they are grown in large borders or allowed to naturalize in the back of the landscape.

In frosty climates, the Castor bean plant is the best way to create a quick tropical effect.

Many plants are poisonous to a degree, including many popular and commonly used landscaping plants. We can ban them from our own gardens, but will still encounter them in other gardens, parks, in the wild, etc.

The best thing you can do to protect your children or grandchildren from accidental poisoning is to teach them to never ingest any plant parts unless first approved by an adult.

If you like the exotic look of Castor bean plant, but want to avoid any poisonous plants in your garden, a safe alternative is “Fatsia japonica” (also known as false Castor bean plant). It looks almost similar, but is harmless.

Marc Vijverberg


Huge bright green shiny leaves adorn this lovely thick-trunked Cretian form of the “Castor Oil Plant”.

This is the quite rarely offered true wild form bearing dazzling bright red flower buds and seed pods amongst large dark green leaves.

If grown in warm climates it will ultimately make a sturdy tree. Please note that these seeds are extremely poisonous if eaten.SUPPLIED AS A PACKET OF SEEDS

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Spain Info castor bean plant San Francisco De Asis, Urb Marina, San Fulgencio, 03177, Alicante, Spain. 38n21, 0w29.

Then along came a September windstorm and the whole thing crashed to the ground, flattening the poor salvias, which may have been praying to be put out of their misery. I wandered about the wreckage, examining some of the burst pods and their beautiful mottled brown seeds — the source of castor oil — which are about the size of pinto beans.

I knew enough not to pop one in my mouth, because they contain a protein called ricin, which is highly poisonous. Wayne Armstrong, a botany instructor at Palomar Junior College in San Marcos, Calif., said ricin is 6,000 times more poisonous than cyanide and 12,000 times more poisonous than rattlesnake venom.

Castor beans “are unquestionably among the most deadly seeds on earth, and it is their irresistible appearance that makes them so dangerous,” Mr. Armstrong wrote in a 1982 article in Environment Southwest magazine, which I’d unearthed at the library of the New York Botanical Garden.

The castor bean file there disclosed other tidbits: Agatha Christie used the poison in her 1929 mystery, “The House of Lurking Death,” in which an heir and an heiress die from ricin mixed into fig paste. And in 1979, there was a true case of a poisoning in London, in which a Bulgarian diplomat was pricked by the tip of an umbrella containing ricin and died.

Despite its poisonous reputation, the castor bean, also known as Palma Christi, has been grown for thousands of years and has been used for everything from lamp oil to medicine. The seeds have been found in Egyptian tombs from as far back as 4000 B.C. They were most popular as a purgative and skin ointment, but they were also burned to smoke out gods and goddesses suspected of making someone ill. The oil was also supposed to make a woman’s hair grow.

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