Ricinus communis L. - Castor Bean

Ricinus communis plant

Family - Euphorbiaceae

Stems - To 5m tall, glabrous, glaucous, suffrutescent (with age) or entirely herbaceous, branching, reddish, greenish, or purplish.

Leaves - Alternate, peltate, long petiolate, palmately 5 to 7 lobed, toothed, glabrous, to +30cm broad.

Ricinus communis leaf

Inflorescence - Axillary racemes or loose panicles to +50cm tall, on thick peduncle.

Ricinus communis inflorescence

Staminate Flowers - At base or lower portion of inflorescence, apetalous, pedicillate. Calyx typically 5-parted, reflexed. Stamens many, the filaments branching. Anthers yellow.

Ricinus communis flowersStaminate flowers.

Pistillate Flowers - Capsules red, green or purple, covered with dense spines, +1.5cm in diameter, 3-seeded. Seeds mottled with copper, black, and bronze colors. Styles 3, red.

Ricinus communis flowers   Ricinus communis seedSeed.   TickTick.

Flowering - August - November.

Habitat - Mostly cultivated. Also escaped to roadsides, railroads, waste ground, disturbed sites.

Origin - Native to Asia.

Other info. - This plant is the source of castor beans (used in ornamentation) and castor oil(pressed from the seeds). The plant is also more toxic than any other plant to humans. The seed cake which is left over after pressing contains a protein toxin known as Ricin which replaces a vital enzyme in cellular metabolism causing the shutdown of protein synthesis in the body. No protein - no life. The toxin contains an alpha section, which causes the cell shutdown, and a beta section which carries the molecule across the cell membrane.
Ricin has been used for assassinations, and has been experimented with for biological warfare. The LD 50 of Ricin is around 1/1000000 of the animals weight. It is VERY toxic. Pests which feed on the plant are usually killed.
The entire plant is toxic, but the seeds more than any other part.
The plant is, however, very striking in cultivation and many horticultural varieties exist. The typical species is mostly a green plant but I have found that the red form is very common in Missouri so I placed the plant in the red flowers section of this site.
The name Ricinus communis means "common tick" because the seeds resemble ticks.

Red variety photos taken at Powell Gardens, 9-2-99. Typical species photos taken off Cypress Gardens Blvd., Winter Haven, FL., 3-26-00.