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Featured Plant

One of the earliest mentions of Ricinus communis as a medicinal plant appears in the Ebers papyrus, a document of around 700 prescriptions penned by an Egyptian priest dating to 1500BC. Its value to the ancient Egyptians, whether medicinal or ritual, is demonstrated by many examples of the bean-like seeds discovered in their tombs, some as old as 4000 years. Since then, it has been used to treat a range of ailments, and its use is continued to this day. Ricinus grows as a shrub or small tree in its native tropics but, due to its tender nature, must be grown from seed each year in the RCP garden. This year it can be seen growing under the Ginkgo in front of William Harvey House, and in the small island bed on the main lawn. Its distinctive red, five-pointed leaves gave rise to its name Palma Christi, as seen in early herbals such as John Gerard's. The more common name – Castor oil plant – refers to the high levels of ricinoleic acid found in the seed, and the widely-used product castor oil. Castor oil has traditionally been used as a laxative in many cultures, taken both internally and externally. While the laxative effect is attributed to the high ricinoleic acid content of the seeds, the seed coating also contains two highly toxic compounds: ricinine and ricin. Ricin is a fast acting poison, with symptoms appearing around 10 hours after ingestion. Two beans can be fatal. One of the most famous cases of ricin poisoning took place in London in 1978 when a Bulgarian secret service agent injected a defecting agent with a tiny metal pellet, mounted onto the tip of his umbrella. The unfortunate agent, unaware of the attack, died mysteriously 4 days later. The metal pellet was later found by a pathologist, lodged in the victim’s thigh. It contained traces of ricin. Castor oil can still be bought in health food stores in the UK, marketed as a treatment for various complaints, including a variety of skin conditions, as a hair conditioner, as a massage oil, and as a laxative. Ricinus communis is also an important plant horticulturally, grown as a popular ornamental in the UK, but considered an invasive weed in warmer parts of the world.


Purgative, oil extracted from the bean (Castor oil), being used as a laxative
Van Wyk, Wink, BE . (2017). Medicinal Plants of the World. CABI.

One of its earliest mentions appears in the Ebers papyrus, a document of 700 prescriptions penned by an Egyptian priest dating to 1500BC
Wee, Yeow Chin. (2005) Plants that Heal, Thrill and Kill, SNP Reference.


Palma Christi
L'Obel, M, de Pena, P. (1571). Nova Stirpium Adversaria. Thomas Purfoot, London. p. 306

Other use

Food additive: flavouring, also for protective coating of tablets; Fuels: potential as petrol substitute/ alcohol; Invertebrate food: silk worms; Materials: beads, lipids.

This was known as Palma Christi, or Figuera di l’inferno (the fig from hell) according to Lobel. The coat of the seed of this plant from Southern Europe and North Africa is the source of the poison ricin, best known for the umbrella murder in 1978 when the Bulgarian secret service was alleged to have killed Georgi Markov with a pellet containing ricin (although none was found), using an air gun disguised as an umbrella, on Waterloo Bridge in London. The seeds also produce castor oil (which does not contain ricin), formerly used as a laxative. The leaves are used worldwide as a herbal remedy for stomach complaints. Woodville describes at length how castor oil is extracted, but neither he nor Lindley mention that the seeds are poisonous. Lyte says that the oil, then known as Oleum cicinum, was good for rubbing on the skin, and the leaves for swollen eyes and erysipelas, but that the seed makes one vomit ‘with much payne and greefe’. Two seeds ingested are said to be fatal, but vomiting as a reaction to poisons protects the unwary.
Oakeley, Dr. Henry. (2011). A Year in the Medicinal Garden of the Royal College of Physicians, revised edition. Royal College of Physicians, London. p.61 link

Used currently as an industrial lubricant and in the manufacture of polymers
Van Wyk, Wink, BE . (2017). Medicinal Plants of the World. CABI.


Seed is high in ricinolieic acid Two toxins – ricinine and ricin, found in the seed coat
Van Wyk, Wink, BE . (2017). Medicinal Plants of the World. CABI.


Ricinus communis L. Euphorbiaceae Castor oil plant. Palma Christi. Distribution: Mediterranean, E Africa, India. The seeds themselves are pretty, brown, bean-like usually with gold filigree markings on them, and the interior of the seed is the source of castor oil. The outer coat of the seed is the source of the poison ricin, famous (infamous) for the umbrella murder of Georgi Markov on Waterloo Bridge in 1978. The KGB are alleged to have killed Georgi Markov, a dissident Bulgarian journalist, with a pellet containing 0.28mgm of ricin fired into his leg using a specially adapted air gun in an umbrella. While his symptoms were those of ricin poisoning, no ricin was ever found in the pellet that was extracted from his leg. Two seeds, chewed and ingested are said to be fatal, but most people vomit and get rid of the toxin. Ducks are resistant to ricin, and need to ingest more than 80 to be fatal! In Peru the leaves are used as a tea for stomach ache, although they contain small amounts of ricin. It is called Palma Christi in early herbals because of the five pointed leaves, which schematically represent a hand. It is a monotypic genus in the spurge family.
Oakeley, Dr. Henry F. (2013). Wellcome Library notes. link

Geographical distribution

  • Africa

Ricinus communis L.

Genus: Ricinus
Species: communis L.
Common names: Castor Oil Plant, Palma christi
Distribution summary: Pantropic
Habit: Annual
Hardiness: H2 - Tender; cool or frost-free greenhouse
Garden status: Not currently grown
Flowering months: July, August, September
Reason for growing: Medicinal, other use, toxic

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