Castor oil was one of those dirty words that I never wanted to hear when I was growing up. It seemed to be a cure for everything because every time I turned around, somebody was standing there with a spoonful of the nasty stuff, just waiting to poke it into my mouth. It's flavor was enough to make me sicker than I ever thought of being.

Last summer I received a package of castor beans from a friend with the warning in red letters: TOXIC. I planted them in a couple of places in my garden, and they are truly lovely plants. Actually I have a few well-loved, beautiful plants that contain toxins, but I have learned to be very careful over the years. There are no small children in my neighborhood, and I have taught my little grandson to always ask before he touches anything in my garden when he visits. I also have roses, and he certainly knows to not touch them. Eventually he will learn the difference and will know why some plants are off limits and others are not harmful.


But let's venture back to the topic of the castor oil plant. When archeologists first explored the 4,000 year old Egyptian tombs, they found sparkling gems, statuary, ancient mummies, and some tiny oval objects that they paid little attention to. When they did take a closer look at them, they found them to be glossy and mottled, less than a half inch long, and looking like pieces of polished marble. Further studies showed the "stones" to be millennia old castor beans, the seeds of an African tree that now grows in warm areas throughout the world and the bane of my existence when I was young. It is also cultivated by European and American gardeners as a foliage plant, which is what most of us have in our gardens.

The castor oil plant, Ricinus communis, in its native habitat is a tree that reaches 30 to 40 feet high. If sown early, protected, and kept at a temperature of around 68 F the castor oil plant will grow at the rate of about 3 feet a year. In that environment it bears broad, deeply lobed leaves on long stalks. The leaves are purple bronze when young, and gray green or lovely dark maroon when mature. The female flowers, borne in clusters above the male flowers, develop into bur-like capsules containing 3 seeds each. When the capsules are mature and dry out, they explode, scattering their beans. There are shrubby dwarf strains no more than 5 feet high that have been developed in cultivation, and they bear non-exploding seed capsules.

The Egyptians used castor oil, derived from the beans, as lamp oil. They also purged their systems several times a month by drinking the oil mixed with beer. The "Ebers Papyrus" is an ancient Egyptian medical treatise believed to date from 1552 BC. Translated in the mid-1800s, it describes castor oil as a purgative. The Greeks and Romans took note of how the Egyptians used it, wisely decided the beans were poisonous, and used the oil only externally. It was not until the late 18th century that the foul tasting substance regained its ancient role as a laxative. The use of castor seed oil has been documented in India since 2000 BC. There is was used to fuel lamps, as well as for its purging qualities. It has been used in China for centuries as an internal treatment or externally for dressings. Aside from its use for purging, it was also used in some cultures externally as a treatment for arthritis, and for the cure of dermal fungus. There too, is the ever-present fact that it was widely used in some cultures during the rituals of sacrifice to please the gods. The death of an adult from castor beans is slow and agonizing.

The bean's poisonous substance, ricin, is one of the deadliest toxins known; eating a single castor bean can kill a child. Fortunately, extracting the oil without the ricin is a fairly simple process. The key is temperature. Heat is used to extract oil from most seeds, but when castor beans are heated, the ricin from the bean is distributed throughout the oil. When the beans are hulled and crushed at temperatures below 100 F, they yield a poison-free oil, rich in another substance, ricinolein. Ricin irritates the intestines and causes, for lack of a more gentile term, rapid purging. Ricinolein is not poisonous.


Castor oil has several commercial applications. Because it is insoluble in benzine and has a very low freezing point, it is well suited for the lubrication of airplane engines. It is also used in hydraulic brake fluids and in biodegradable laundry detergents, as well as in paints and varnishes. Oil meant for those purposes is extracted by heat and is poisonous.

Although castor is indigenous to the southeastern Mediterranean region, Eastern Africa and India, it is also widespread throughout tropical regions. It is widely grown as a crop in Ethiopia. We also find it in abundance as an ornamental plant here in North America.

The castor oil plant is the host plant of the Common Castor butterfly (Ariadne merione) and the Castor Semi-looper Moth (Achaea janata). Among birds, it is a favorite food of the Tambourine Dove.

In Brazil, the castor plants grow quite freely. The fruits are used by children as slingshot balls. The seeds are called Mamonas in that country and oil from the Mamonas is now being used to produce biodiesel in poor rural areas there.

As I sorted seeds recently, getting them ready for winter sowing, I took another look at my castor seeds. I had planted the ones my friend sent last summer, and my supply had grown greatly. That was when my battle with castor oil came drifting into my mind. If I could go back in time, instead of clamping my mouth shut, hiding in the closet, spitting the castor oil across the room, or running away from home, I would simply tell my mother the nasty stuff she was pouring into me was not only poisonous, but it was used to make planes fly, trucks drive, and car brakes stop.

No doubt she would have accused me of telling tall tales again.

I think with proper education and caution, we can allow most toxic plants to safely grow in our gardens. The truly sad thing is, if we were limited to only non-toxic plants, we would never be able to enjoy daffodils, rhododendrons, jasmine, lantana, foxgloves, azaleas, wisteria, or crocuses.

Images courtesy of PlantFiles