Ricinus communis

Ricinus communis_castorbean_JM DiTomaso
Photo courtesy Joseph DiTomaso

Common names: castor bean

Ricinus communis (castorbean) is an herbaceous plant or semi-woody large shrub or small tree (family Euphorbiaceae). It grows quickly in mild climates and has escaped cultivation to become a noxious weed in southern and central California. Castorbean contains ricin, an extremely toxic chemical that can kill an adult who consumes only four to eight seeds. Handling foliage and seeds can cause severe dermatitis.

Rating: Limited

Cal-IPC Resources

  • Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.
  • CalWeedMapper - Statewide maps, climate models, and reports.
  • Cal-IPC News - Our quarterly newsletter. Each issue is available as a pdf.
  • Cal-IPC Symposium Proceedings - Presentations and papers from our annual Symposium.
  • Don't Plant a Pest! - Select your region to find non-invasive alternatives to ornamental species. Also see our statewide brochure on trees.

Other Resources

  • USDA PLANTS database -
    Federal database with information on identification and distribution, and links to websites in individual states.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from the UC Berkeley Jepson Herbarium.
  • CalFlora - Distribution information by county based on submitted observations and herbarium specimens.
  • CalPhotos - Images of plants taken mostly in California.
  • Natural Resource Projects Inventory - State database with information on resource management projects throughout California. Query by the species of interest.

Symposium Presentations

  • Reinoehl, S. and C. Zaich (2010). The Matilija Dam Ecosystem Restoration Project. Cal-IPC 2010 Symposium Ventura, CA, California Invasive Plant Council
  • Burkhart, B. and M. Kelly (2007). How to develop user-friendly riparian corridor invasive exotic species/habitat restoration master plans: Experiences on the San Diego and Otay Rivers. California Invasive Plant Council Symposium 2007. San Diego, CA, California Invasive Plant Council.
  • Connick, S. and M. Gerel (2004). Partnering to prevent invasions of plants of horticultural origin. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Dickerson, E., C. Brigham, et al. (2004). Ecohelpers: Education and ecological restoration in Southern California. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Archbald, G. (1998). Mechanical control methods: beyond weed bashing. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Devender, T. R. V., R. S. Frlger, et al. (1997). Exotic plants in the Sonoran desert region, Arizona and Sonora. California Exotic Pest Plant Council Symposium '97. Concord, CA.

Cal-IPC News Articles

  • Burkhart, B. and M. Kelly (2005). Which weeds dominate southern California urban riparian systems? Cal-IPC News. 13: 4-5,12.
  • Connick, S. and M. Gerel (2005). Don't sell a pest: A new partnership to prevent plant invasions through horticulture. Cal-IPC News. 13: 4-5,14.
  • Neill, B. and T. A. Angeles (2005). The basal bark method of applying triclopyr herbicide. Cal-IPC News. 13: 8-9.
  • Kelly, M. (1999). Roundup of Arundo projects reveals commitment, strategic weakness. CalEPPC News. 7: 4-9.
  • DiTomaso, J. (1998). Results of the CalEPPC questionnaire at Symposium '98 in Ontario. CalEPPC News. 6: 4.
  • Goode, S. (1998). Legendary stewardship award. CalEPPC News. 6: 10.
  • Stein, E. D. and V. Vartanian (1997). Killing the beast: A cooperative approach for control of Arundo donax in the Santa Ana River watershed. CalEPPC News. 5: 4-6,8.
  • Perala, C., D. A. Hoover, et al. (1993). Control of exotic plants in an herbaceous understory. CalEPPC News. 1: 4-6.