Tuesday, November 22, 2011

Castor Bean

Castor bean (Ricinus communis) is a spectacular plant native to tropical regions of the Eastern hemisphere. Growing up to fifteen feet high with leaves the size of large pizzas (16" diameter), walking through a patch of castor bean plants truly feels like being in a jungle. We found them thriving in South Phoenix at the Tres Rios Wetland Preserve, where effluent from a sewage treatment plant is being used to restore wildlife habitat near the confluence of the Salt, Agua Fria and Gila Rivers. Conversely, the wetlands serve as a natural purification treatment for wastewater before it returns to the river system.

Castor, which is not really a bean, but a member of the Spurge Family (Euphorbiaceae), is well-known for its use in folk medicine, primarily as a powerful laxative. However, the seeds, from which the oil is derived, are also highly toxic. The main toxic element, ricin, is reputed to have been used in espionage and torture. Ingestion of a handful of seeds can result in painful death. This does not seem to deter horticulturists who still cultivate many hybrids of the species for use as ornamentals. Wild castor bean in the Phoenix area are escapees from urban gardens, where the lush growth is welcome in our sometimes austere desert environment.

Orion in front of a field of castor bean plants at Tres Rios Wetlands

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