Ricin is derived from the castor plant that makes castor oil.

NPR: Attorney: Miss. Man Denies Mailing Ricin To Obama

Roger Wicker, a Mississippi Republican, received a letter containing ricin, a toxin derived from the castor oil plant.

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Plants in this family, which include the rubber tree, castor oil plant and the cassava shrub, are typified by small blossoms, the researchers comment.

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