Ricinus communis Castor Bean is a horticultural annual grown for its big palmate leaves, up to 3' wide. It can become a 40' tree in tropical areas, but it is generally grown as an annual. The plant is widely used as a decorative plant in parks and other public areas. However, it is important to note that the whole plant is very poisonous, even one seed has been known to be lethal to children. Castor seed is the source of castor oil, which has a wide variety of uses. Castor oil has many uses in medicine and other applications and is also effective as a motor lubricant. Despite its many uses, it is important to be cautious when handling the plant due to its toxicity.