The castor bean (Ricinus communis) is not a true bean, but a member of the Euphorbiaceae or spurge family. It is the source of castor oil, which has a wide variety of uses, and ricin, a poison.

The name Ricinus is a Latin word for tick; the seed is so named because it has markings and a bump at the end which resemble certain ticks.

Although castor is probably indigenous to Eastern Africa, today castor is distributed worldwide. Castor establishes itself easily as a "native" plant and can often be found on wasteland, near rail roads and has recently also been used extensively as decorative plant in parks etc.

Castor beans

Castor seed have been found in Egyptian tombs dating back to BC 4000. Herodotus and other Greek travellers have noted the use of castor seed oil for lighting and body anointments.

The use of castor seed oil in India has been documented since BC 2000 for use in lamps and in local medicine as a laxative. Castor seed and its oil has also been used in China for centuries, mainly described in local medicine for internal use or use in dressings.

Although monotypic, the castor plant can vary greatly in its growth habit and appearance. Some castor plants are perennials which can take the size of small trees, and other plants are dwarf types and are grown as annuals. There also exists an enormous variation in leaf shape and colouring which has led to a selection by breeders for use as ornamental plants.

Castor seed contains between 40% and 60% oil that is rich in tryglycerides, mainly ricinolein .

Global castor seed production is around 1 million tons per year. Leading producing areas are India, China, Brazil and the former USSR. There are several active breeding programmes.