Castor oil plants are having a field day around here this year — they’re crowding the roadsides and spreading in vacant lots. The plant is invasive, as well as highly toxic, and I’m not happy to see its proliferation in the Santa Monica Mountains.

However, castor oil itself has many medicinal and industrial uses. I remember it from childhood (stories, not direct experience) as a nasty laxative/purgative. Castor oil was used as an instrument of coercion under the 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.

On the less sinister side, modern uses of natural, blended, or chemically altered castor oil products include:

• A non-freezing, pressure-resistant lubricant
• A raw material for some varieties of biodiesel
• A component of many cosmetics
• An anti-viral, -bacterial or -fungal ingredient in many ointments
• A modifier that improves the flow characteristics of cocoa butter in the manufacture of chocolate bars
• A repellent for moles and voles in lawns

Castor seeds have been found in Egyptian tombs dating back to 4000 BC; the slow-burning oil was mostly used to fuel lamps. Herodotus and other Greek travellers noted the use of castor seed oil for lighting, body ointments, and improving hair growth and texture. Cleopatra is reputed to have used it to brighten the whites of her eyes.

So there you have it. An extremely useful (and quite pretty) plant — just not one I want growing around here.