The castorbean plant Ricinus communis has been cultivated for centuries for the oil produced by its seeds. The Egyptians burned castor oil in their lamps more than 4,000 years ago. Thought to be native to tropical Africa, the plant is a member of the spurge family. The seeds with hulls removed contain 35 to 55 oil. The seeds, leaves, and stems of the plant contain ricin and ricinine, which are poisonous to humans and animals. Eating a castorbean causes nausea, and eating several may cause death. These toxic compounds are not present in the oil. Castorbeans are grown on a limited scale in the United States. Demand for the crop peaked in the early 1950s, when the federal government wished to increase supplies of castor oil for military applications in the event of a national emergency. The government guaranteed farmers, particularly in the Southwest, ten cents per pound for the seeds, which were grown under contract with castor oil processors. The castorbean plant grows well in soil of medium texture. It is best adapted to southeastern Kansas, Missouri, southern Illinois, southern Indiana, Tennessee, Kentucky, and parts of Oklahoma and Texas. With irrigation, it also grows well in the Southwest.

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