Emex spinosa

Emex spinosa by Ron Vanderhoff
Photo by Ron Vanderhoff

Synonyms: Rumex spinosus

Common names: devil's thorn; spiny threecornerjack

Emex spinosa (spiny emex, devil’s-thorn) is an annual (family Polygonaceae) found on California’s south coast. This Mediterranean native is not yet common in California, but it is spreading rapidly and is known to crowd out native species. It frequently infests disturbed areas, especially in coastal habitats. Emex spinosa’s spiny seed pods stick to people and animals, so it spreads quickly along trails and then into undisturbed areas.

Rating: Moderate

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.

    Symposium Presentations

    • None for this species.

    Cal-IPC News Articles

    • None for this species.