Castor Bean is an annual native to the southeastern Mediterranean and East Africa. Its Latin name, Ricinus, means tick because the seeds are said to resemble a blood filled tick. It is an ancient plant that has been cultivated for thousands of years and considered by many civilizations to be an important medicinal herb. Seeds have been found in Egyptian tombs dating to 4000 BC. The Greeks and the Romans used the oil for wound healing, but the Greeks believed that the oil should only be used externally. In the Middle Ages, the Europeans used the oil as a kind of liniment and also as a lubricant. In the 18th century, the extraordinary capabilities of castor oil as a laxative were discovered, and with this discovery, the plant’s popularity exploded. Thomas Jefferson wrote about the plant in his garden book and today the plant is prized as a garden ornamental.
Unfortunately, both the plant and especially its seeds are poisonous. The plant’s toxicity comes from ricin, a blood-coagulating protein that is found in all parts of the plant and its seeds. For a child, ingestion of as little as four seeds can prove fatal. In adults, the plant and its seeds can produce nausea, vomiting, diarrhea, blurred vision and skin irritations.
Despite its poisonous qualities, the Castor Bean plant is a much beloved member of the garden. Sometimes towering 8-10 feet, the stems which bear a profusion of huge, red-veined leaves lend a tropical ambiance to any garden. The plant is grown for its height and its leaves. The flowers are much less dramatic. It is also said to prevent moles and voles and to discourage other rodents, specifically rabbits and mice.
The plant can be grown easily from seed. It requires full sun. Plant the seeds 1 inch deep in rich, well-drained soil. The seeds will germinate in less than 2 weeks. The plants will probably need frequent watering, and like a nitrogen rich fertilizer. Mature plants will require at least 30 inches between plants. Some old-time gardeners recommend planting a living fence of Castor Bean plants around the vegetable garden. This, they say, will keep out all of the varmints.
Although it is native to the Ethiopian region of tropical east Africa, the castor bean or castor plant (Ricinus communis) has become naturalized in tropical and warm temperate regions throughout the world, and is becoming an increasingly abundant weed in the southwestern United States. Castor plants are very common along stream banks, river beds, bottom lands, and just about any hot area where the soil is well drained and with sufficient nutrients and moisture to sustain the vigorous growth. Although the seeds or beans are extremely poisonous, they are the source of numerous economically important products and are one of earliest commercial products. Castor beans have been found in ancient Egyptian tombs dating back to 4000 B.C., and the oil was used thousands of years ago in wick lamps for lighting. To many people the castor plant is just an overgrown, undesirable weed, and yet it produces one of nature’s finest natural oils.
Castor plant is a robust annual that may grow 6 to 15 feet (2-5 meters) in one season with full sunlight, heat and adequate moisture. In areas with mild, frost-free winters it may live for many years and become quite woody and tree-like. The large, palmately lobed leaves may be over 20 inches (50 cm) across and resemble a tropical aralia. There are several cultivated varieties with strikingly different foliage colorations, including black-purplish, dark red-metallic, bronze-green, maroon, bright green with white veins, and just plain green. Although it grows very rapidly with little care or insect pests and produces a mass of lush tropical foliage, its use in cultivation should be discouraged because of the extremely poisonous seeds or “beans.” This is particularly true where small children might be attracted to the large, beautifully-mottled seeds which are produced in prodigious numbers.
