Castor is indigenous to the southeastern Mediterranean Basin, East Africa, and India, but is widespread throughout tropical regions (and widely grown elsewhere as an ornamental plant).

The seed also contains ricin, a highly potent water-soluble toxin, which is also present in lower concentrations throughout the plant [citation needed].

The glossy leaves are 15–45 centimetres (6–18 inches) long, long-stalked, alternate and palmate with five to twelve deep lobes with coarsely toothed segments.

The flowers lack petals and are unisexual (male and female) where both types are borne on the same plant (monoecious) in terminal panicle-like inflorescences of green or, in some varieties, shades of red.

[7] The fruit is a spiny, greenish (to reddish-purple) capsule containing large, oval, shiny, bean-like, highly poisonous seeds with variable brownish mottling.

The genus Ricinus[10] also exists in zoology, and designates insects (not ticks) which are parasites of birds; this is possible because the names of animals and plants are governed by different nomenclature codes.

[13] It has another common name, palm of Christ, or Palma Christi, that derives from castor oil's reputed ability to heal wounds and cure ailments.

After hauling their harvest into their nests and pulling off the delicious part, ants discard the rest of the seed into their trash pile, where the future plant starts to grow.

[citation needed] Although Ricinus communis is indigenous to the southeastern Mediterranean Basin, Eastern Africa, and India, today it is widespread throughout tropical regions.

[5] However, it can grow well outdoors in cooler climates, at least in southern England, and the leaves do not appear to suffer frost damage in sheltered spots, where it remains evergreen.

[20] The castor oil plant produces abundant amounts of very light pollen, which easily become airborne and can be inhaled into the lungs, triggering allergic reactions.

Leading producing areas are India (with over three-quarters of the global yield), China and Mozambique, and it is widely grown as a crop in Ethiopia.

Herodotus and other Greek travellers noted the use of castor seed oil for lighting, body ointments, and improving hair growth and texture.

[29] The use of castor bean oil (eranda) in India has been documented since 2000 BC in lamps and in local medicine as a laxative, purgative, and cathartic in Unani, Ayurvedic, siddha and other ethnomedical systems.

"[32]In Haiti it is called maskreti,[33] where the plant is turned into a red oil that is then given to newborns as a purgative to cleanse the insides of their first stools.

[35] Castor oil was used as an instrument of coercion by the paramilitary Blackshirts under the regime of Italian dictator Benito Mussolini and by the Spanish Civil Guard in Francoist Spain.

Dissidents and regime opponents were forced to ingest the oil in large amounts, triggering severe diarrhea and dehydration, which could ultimately cause death.

[36] Extract of Ricinus communis exhibited acaricidal and insecticidal activities against the adult of Haemaphysalis bispinosa (Acarina: Ixodidae) and hematophagous fly Hippobosca maculata (Diptera: Hippoboscidae).

[37] Members of the Bodo tribe of Bodoland in Assam, India, use the leaves of the plant to feed the larvae of muga and endi silkworms.