The bean of the castor-oil plant, Ricinus communis, is used in the production of castor vegetable oil and ricin, a poison. Sasha Vasko/via Flickr hide caption toggle caption Sasha Vasko/via Flickr Shots - Health News How Ricin Can Sicken And Kill April 17, 2013 Ricin is a naturally occurring toxin that's found in castor beans. Castor-oil plants, the source of beans, are popular with gardeners. You can get sick by eating beans. But purified ricin can be made pretty easily and used for no-good.