Castor bean or castorbean (Ricinus communis) flowers develop into seed pods that hold the castor bean, which can be harvested and used for oil. While the castor bean resembles the pinto bean in size and shape, it contains the poison ricin--one of the most toxic substances known to man--and cannot be eaten. Castor bean plants can be identified by their flowers, as well as the fruit clusters that develop from the flowers, which are more showy and may provide easier identification.
Castor bean plants develop flower stalks that range in length from 6 to 12 inches. Male and female flowers develop off these stalks, either alternating or with female flowers clustered along the top and male flowers along the bottom.
Castor bean flowers are small and generally inconspicuous, especially when compared with the spiky fruit clusters that develop. The flowers have no true petals but are instead a cluster of stigma; they resemble clover in appearance.
Flowers range in color from pink or red to greenish-white. Wayne's Word from Palomar Community College District display an image of a Castor bean plant with green male flowers and red female flowers. The color and arrangement of flowers varies by species.
Castor bean plants bear flowers throughout much of the year, so some plants may be in flower while others display fruits or bear only flower stalks.
Castor bean plants may be easier to identify by their fruit, which is spiny on the outside and bright red in color. Some varieties have bright green fruit instead. The fruit pods splits into three parts when it matures; each contains once Castor bean seed.
Native to Africa, castor beans are cultivated throughout the Midwestern United States for their oil. Purdue University notes that farmers in Kansas, Missouri, Illinois, Tennessee, Kentucky and Oklahoma grow castor beans.