Ricinus communis

Ricinus communis_castorbean_JM DiTomaso
Photo: Joseph DiTomaso

Common names: castor bean

Ricinus communis (castor bean) 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. Castor bean 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.

Cal-IPC Rating: Limited?

CDFA Rating: None?


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.

Weed Management Notes

  • Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

Other Ricinus communis Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - Distribution map and records of this species in California.
  • CalWeedMapper - Distribution map of this species in California with ability to determine regional priorities.
  • EDDMapS - Distribution of this species in North America.
  • Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.
  • Additional photos

    Ricinus communis_female (top) and male (bottom) flowers_copyright2019_NealKramer
    Ricinus communis (castor bean) female (top) and male (bottom) flowers. Photo: &#169 2019 Neal Kramer
    Ricinus communis_fruits (immature)_copyright2011_NealKramer
    Ricinus communis (castor bean) fruits (immature). Photo: &#169 2011 Neal Kramer
    Ricinus communis_leaf_copyright2011_NealKramer
    Ricinus communis (castor bean) leaf. Photo: &#169 2011 Neal Kramer
    Ricinus communis_seeds_RonVanderhoff
    Ricinus communis (castor bean) seeds. Photo: Ron Vanderhoff