Castor
Family Euphorbiaceae
Ricinus communis, castor oil plant (R. communis 1), is a variable annual herb or shrub-like perennial, 1-7 m high, with palmate leaves (R. communis 5). The unisexual flowers are borne in terminal panicles, 10-40 cm long (R. communis 2, R. communis 6), with male flowers at the base and female flowers at the top. The male flowers are green with numerous stamens; the female ones are also green, with a superior ovary with 3 stigmas. All flowers are 5-7 mm long. The fruit is a globose capsule (R. communis 3), about 2 cm in diameter, containing ovoid shining mottled seeds (R. communis 4), which are rich in oil. This castor oil contains a toxic protein, ricine, which makes it unsuited for human consumption. Therefore the bulk is used in industry.
Distribution
Castor is of African origin and grows wild in East and North Africa and in the Near- and Middle East. It was cultivated in ancient Egypt, where the oil was used as lamp oil. It was taken at an early date to India, but it reached the New World only after Columbus. Today the plant is spread over most tropical and subtropical countries.
Use
Up to the 20th century, castor oil was mainly used in medicine, especially as a purgative. In the course of the century many industrial applications of the caster oil followed: the production of soap, high grade lubricants, printing inks, paints and varnishes, polishes, candles and crayons. Part of the oil is used in ointments and cosmetics.
Biggest producers are Brazil, India, China, Russia and Thailand.