# Palm of Christ (Ricinus communis)

**Palma Christi**

**Known today as.** The castor-oil plant, *Ricinus communis* (note XLII). The oil “of castor” in the anointings is this oil, not the animal substance castoreum.

Kind: Plant  
Poisoning: The ribosome-inactivating lectins (https://thethinkingpress.org/materia-medica/poisons/lectin)  
Toxic: yes

> **Caution.** 

## What did Canale use it for?

Its flowers in a conserve; in the bath; its oil for anointing; among the amulets (chs. 6–7, 9–10).

## What does modern science say?

Castor oil is a stimulant laxative taken by mouth, and a skin-conditioning oil. See Castor-oil plant, seeds of, p. 215.

## Pharmacognosy and toxicology

- **ricin**: a ribosome-inactivating lectin of the seed
- **ricinine**: an alkaloid
- **ricinoleic acid**: 90 per cent of the oil

**Mechanism.** The castor plant. The oil, pressed cold, is free of ricin: in the gut lipase frees ricinoleic acid, which activates the prostaglandin receptor EP3 on the gut muscle, the purge, and on the uterus, which is why it was given to start labour. The seed is another matter: ricin shuts down the ribosome, and a few chewed seeds have killed. The flowers in a conserve and the oil in the bath are harmless.

**Dose.** The oil at 15–60 ml purges; one to eight chewed seeds have been fatal, though most reported ingestions survive.

**Standing.** Castor oil has an EMA monograph (2016) for short-term constipation; it is not on the WHO essential list, which carries senna and lactulose instead; ricin is a scheduled chemical weapon.

## What did the older authorities say?

**Pliny.** Describes the cicus or croton of Egypt, in Spain shooting up to the size of an olive tree, with a stem like the ferula, the leaf of the vine, and a seed like a small pale grape, “our people are in the habit of calling it ricinus, from the resemblance of the seed to that insect”: the oil, boiled out in water or in Egypt pressed from salted seed, is “repulsive” to eat “but it is very useful for burning in lamps”; and castor oil taken with an equal quantity of warm water “acts as a purgative upon the bowels,” said to work particularly on the diaphragm, and is used for the joints, indurations, the uterus, the ears, and burns.

## Sources

- Pliny the Elder, *Natural History* 15.7, 23.41, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library.
- Tunaru, S., et al. (2012). “Castor oil induces laxation and uterus contraction via ricinoleic acid activating prostaglandin EP3 receptors.” *PNAS* 109.
- Audi, J., et al. (2005). “Ricin poisoning: a comprehensive review.” *JAMA* 294.

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*Palm of Christ.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/palm-of-christ

Historical description, not medical advice.