Q: Could you help me determine the name of the plant that just appeared in my garden one day in late summer? It had interesting foliage so I let it grow. It may be an invasive weed but it turned out to have a very pretty and unusual flower. Are there any problems with this plant? Folks have been asking for seeds from it.
A: I sent your photos to the University of Florida Herbarium and below is the response from one of the specialist. “The plant is Ricinus communis L., commonly known as Castorbean, Castor Oil Plant, or Palma-Christi, in the Euphorbiaceae (Spurge Family). It is thought to be native to Africa but is widely cultivated as an ornamental and as a source of seed oil used in industry and medicine. It is also widely naturalized. In Florida it has escaped from cultivation and is frequently found on disturbed sites.
The Florida Exotic Pest Plant Council lists it as a category II invasive for northern, central, and southern Florida. It can be safely cultivated as an annual in colder climates, but in northern Florida it often sprouts back from the roots after freezing and the seeds are dormant in the winter and sprout once temperatures have warmed. There are a number of cultivars, some of which are very attractive ornamentals, but because of its aggressive tendencies this plant probably should not be grown in Florida.
All parts (but especially the seeds) are highly toxic if consumed; the toxic principle is called Ricin. Because of its toxicity the oil must heat treated before it is safe to consume medicinally.
For more information on this plant see the following websites:
http://www.floridata.com/ref/R/rici_com.cfm (info on cultivation)
http://www.hort.purdue.edu/newcrop/duke_energy/Ricinus_communis.html (info on uses)
http://www.issg.org/database/species/ecology.asp?fr=1&si=1000&sts= (info on invasiveness)