Emex spinosa

Emex spinosa by Ron Vanderhoff
Photo: 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.

Cal-IPC Rating: Moderate — Alert?

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.

Species ID Card

Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.

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.

There are no Symposium presentations associated with this species yet.

Other Emex spinosa 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

    Emex spinosa_growth habit_RonVanderhoff
    Emex spinosa (devil's thorn) growth habit. Photo: Ron Vanderhoff
    Emex spinosa_male and female flowers, leaves, and stem_RonVanderhoff
    Emex spinosa (devil's thorn) male and female flowers, leaves, and stem. Photo: Ron Vanderhoff