RICINUS COMMUNIS: CHARACTERISTICS, HABITAT, TOXICITY, USES - BIOLOGY - 2025

Ricinus communis is a woody herbaceous plant that belongs to the Euphorbiaceae family. It is a very toxic plant native to the old continent and which grows widely in tropical regions.

Castor bean, as R. communis is popularly known, is native to the Southeastern Mediterranean and East Africa and India, and has been cultivated in all tropical regions as an ornamental plant.

Source: pixabay.com

It is the only member of the genus Ricinus, a monospecific genus that is within the Euphorbiaceae family. Ricinus communis is considered in some cases as the most poisonous plant in the world, as it produces a poisonous glycoprotein, ricin. This deadly phytotoxin is extracted from castor bean seeds, and can cause death in a matter of hours.

The castor bean is characterized by the development of large, palmate-lobed leaves with five deep lobes. Each leaf hangs from a toothed cylindrical petiole about 45 cm long. The flowers of the castor bean are green and imperceptible, and are organized in inflorescence, at the end of a panicle. The fruits are three-lobed capsules with an average length of 2 cm.

Basically castor oil owes its toxicity to the phytotoxin called ricin. It is a toxin that severely affects grass animals, such as horses. Virtually all parts of the plant are poisonous, but it is in the seed that this deadly protein is concentrated.

Castor bean grows wild almost everywhere in the world. In Europe, for example, this plant is grown for ornamental purposes. In Brazil and Paraguay, it is widely cultivated for the extraction of castor oil.

It is a fast growing plant, if grown from seed. However, it has a constant requirement for sun.

characteristics

Bush

Ricinus communis is a woody shrub that can average 12 meters in height. In areas with marked seasons this shrub is deciduous, while in tropical regions castor bean is an evergreen shrub.

Ricinus communis. source: wikimedia commons

The large shrubs have a smooth, robust, little branched stem that is generally light brown to green in color. In some cases, the stem may be red in color. In tropical regions the stem can have an average diameter of 10 cm.

Leaves

Castor bean leaves are large with five to seven deep lobes. Each leaf hangs from a solid, cylindrical, toothed petiole, up to 45 cm long. In turn, the petioles have green-whitish margins.

Generally, the leaves are arranged alternately; and they are toothed, with very prominent veins. They can be between 30 and 40 cm wide. The leaves can be green, purple, tan, reddish, purple-black, or dark metallic.

Source: pixabay.com

In addition, the leaves are star-shaped and those with a penetrating color develop very prominent yellow veins.

Inflorescence

Ricinus communis is a monoecious plant that develops racemose inflorescence, known as panicle. Generally, the female flowers are grouped in the distal region and the male flowers in the basal region of the rachis.

An individual can contain an average of 30 to 50% female flowers, and 50 to 70% male flowers. The flowers are devoid of petals; and the male flowers have a peduncle and a calyx with five unequal sepals welded at the base. In turn, they contain numerous filaments, with smooth-surfaced pollen grains.

Inflorescence of Ricinus communis. H. Zell

The female flowers are constituted by a calyx with five sepals, a style, and three bifid stigmas. In addition, they contain an ovary with three carpels, with one ovule each, covered with soft green spines.

Fruit

In R. communis the fruit is a globose capsule with a long, spiny pedicel. Immature fruits are green and sometimes red, turning brown when ripe. The opening of the fruit is variable and depends on the temperature and humidity of the air.

Castor bean fruit. Source: wikimedia commons

Seed

Ricinus communis seeds are flattened oval in shape and rounded at one end, with a bulge, called a caruncle, at the other. They have a smooth surface and a shiny appearance; and the color varies from gray with red spots to brownish.

The seeds have an average length of 1 cm, with a hard, brittle outer coat and a soft, whitish inner coat. The seeds consist of an embryo with two cotyledons, and the albumen which is compact and oily.

Castor beans. See page for author

Habitat and distribution

Ricinus communis is a plant with a wide distribution, especially in tropical regions. It has its origin in the southeast of the Mediterranean. However, other researchers agree that it originated in Asia, more specifically in India, as it is the region with the greatest variability of R. communis. Still, most researchers accept that castor bean's origin was geographically limited to North Africa.

It is widely cultivated in tropical and subtropical regions of the world. In Europe it is frequently used as an ornamental plant. However, it is a plant that tends to establish easily in arid regions, with annual rainfall of between 700 and 1200 mm.

Altitudinally, Ricinus communis grows frequently in areas between sea level and 2400 masl. In general, castor bean grows in regions where the temperature is equal to or greater than 20 ° C, requiring a time of high temperatures without rain, after flowering.

From the edaphological point of view, Ricinus communis thrives optimally in soils of medium to high fertility, deep, loose, permeable, well drained, and with a pH range between 5 and 7.

Taxonomy

Ricinus communis is the only member of the genus Ricinus, which is within the Euphorbiaceae family.

- Kingdom: Plantae.

- Subkingdom: Viridiplantae.

- Infra kingdom: Streptophyte.

- Super division: Embriofita.

- Division: Tracheophyte.

- Subdivision: Eufilofitina.

- Infra division: Lignofita.

- Class: Spermatophyte.

- Subclass: Magnoliofita.

- Superorder: Rosanae.

- Order: Malpighiales.

- Family: Euphorbiaceae.

- Subfamily: Acalyphoideae.

- Tribe: Acalypheae.

- Genus: Ricinus.

- Species: Ricinus communis Linnaeus.

Toxicity

Ricinus communis is considered by many researchers as the most poisonous plant on the planet, and this is due to the phytotoxin found in the seeds of this shrub. Three toxins have been documented in castor bean, with ricin receiving the most attention, being the most toxic. The other toxins are ricinin and agglutinin, both very dangerous.

Ricin

It is a glycoprotein heterodimer composed of an enzymatic chain A and a lectin, in chain B. The lectin binds to epithelial cells, altering the absorption of nutrients and causing necrosis in the mucosa. Ricin is extremely toxic and as little as 500 µg is enough to cause death in an adult human.

Ricinin

It is an alkaloid that causes neurological damage through binding to GABA receptors. It is also antagonistic to nicotine receptors at muscle junctions.

Agglutinin

It is a lectin that agglutinates erythrocytes and can also be immunogenic and therefore contributes to an allergic response that castor bean can cause in many individuals.

Symptoms

Symptoms of poisoning include diarrhea, which can be watery or bloody, and is often accompanied by severe cramps; abdominal pain; sickness; excessive perspiration; threw up; sudden collapse and death. In some cases it can cause neurological damage such as weakness, seizures, and coma.

In animals, castor toxins can cause liver and kidney death. The mucosa of the rumen, stomach, and small intestines can suffer from congestion and edema. On the other hand, the mesenteric lymph nodes are often swollen and edema, and there may be petechial hemorrhages in the intestine.

In some cases there may be degeneration and necrosis of hepatocytes, and in the renal tubular epithelium. Many of these symptoms develop in the first 6 hours after ingesting castor beans and may last less than 24 hours.

Applications

Ricinus communis is a plant cultivated for horticultural purposes, especially in Europe. It is currently a shrub that grows wild or cultivated in the tropical and subtropical regions of the world.

From a commercial point of view, castor oil is cultivated to obtain the well-known and valuable castor oil. This oil is extracted from the seeds and is widely used in the cosmetics industry. To extract this oil, the seeds are pre-treated to neutralize the toxins that are present.

Castor oil is the only oil soluble in alcohol, being dense and viscous, and is used in the automotive, pharmaceutical, chemical, fertilizer and pesticide, aeronautical, medical, energy industries, etc.

The main castor producers by cultivated area are India, China, Brazil, and Paraguay.

Gardening care

Castor is a fast-growing plant that is easy to establish if grown from seed, although specimens have qualitative requirements for sun. As an ornamental plant, Ricinus communis is planted on the margins of gardens.

The seeds can be directly sown in soils to a depth of 3 cm. It is advisable to soak the seeds overnight before planting them. Each seed should be sown at a distance of 90 to 150 cm apart.

Plants require nutrient-rich, well-drained, moist, and deep soils. It is advisable to sow them on sandy and clayey loams.

Ricinus communis is not a drought tolerant plant, so they have a constant requirement for water. To avoid unwanted spread, the seeds must be prevented from opening and falling to the ground, and burning them is an option.

References

1. Bee Culture. 2018. The useful and versatile castor bean plant. Taken from: beeculture.com
2. Bianchini, M., Pacini, E. 1996. Explosive Anther Dehiscence in Ricinus communis L. Involves Cell Wall Modifications and Relative Humidity. International Journal of Plant Sciences, 157 (6): 739-745.
3. Greenwood, JS, Bewley, JD 1982. Seed development in Ricinus communis (castor bean). I. Descriptive morphology. Canadian Journal of Botany, 60 (9): 1751–1760.
4. Mendes, MG, Santos, CD, Dias, ACC, Bonetti, AM 2015. Castor bean (Ricinus communis L.) as a potential environmental bioindicator. Genetics and Molecular Research 14 (4): 12880-12887.
5. Moore, R., Pasieniuk, J. 1984. Structure of Columella Cells in Primary and Lateral Roots of Ricinus communis (Euphorbiaceae). Annals of Botany, 53 (5): 715-726.
6. Reddy, KRK, Bahadur, B. 1989. Adventitious bud formation from leaf cultures of castor (Ricinus communis L.). Current Science Association, 58 (3): 152-154.
7. Rico, HR, Tapia, LM, Teniente, R., González, A., Hernández, M., Solís, JL, Zamarripa, A. 2011. Guide to grow castor (Ricinus communis L.) in Michoacán. Technical Brochure No. 1. INIFAPCIRPAC Valle de Apatzingán Experimental Field.
8. Sausen, TL, Conçalves, LM 2010. Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions. Acta Botanica Brasilica, 24 (3): 648-654.
9. ScienceDierct. 2019. Ricinus communis - an overview. Taken from: sciencedirect.com
10. Schurr, U., Heckenberger, U., Herdel, K., Walter, A., Feil, R. 2000. Leaf development in Ricinus communis during drought stress: dynamics of growth processes, of cellular structure and of sink – source transition. Journal of Experimental Botany, 51 (350): 1515-15
11. Universal Taxonomic Services (2004-2019). Taxon: Species Ricinus communis Linnaeus (plant). Taken from: taxonomicon.taxonomy.nl