Iris pseudacorus

Iris pseudacorus_yellowflag iris flower_ JM Di Tomaso
Photo: Joseph DiTomaso

Synonyms: Iris acoriformis, Iris bastardi, Iris curtopetala, Iris lutea, Iris paludosa

Common names: yellowflag Iris; pale yellow Iris

Iris pseudacorus (yellowflag iris) (family Iridaceae) invades wetlands and meadows along coastal California and some inland counties. Iris pseudacorus is a fast-growing and rapidly-spreading invasive plant that can out-compete other wetland plants, forming almost impenetrable thickets, in much the same way as cattails do.

Cal-IPC Rating: Limited?

CDFA Rating: B?


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.

Other Iris pseudacorus Information

  • Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.
  • 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

    Iris pseudacorus_yellowflag iris flowers_BobCase_cropped
    Iris pseudacorus (yellowflag iris) flowers. Photo: Bob Case
    Iris pseudacorus_yellowflag iris_Bob Case_cropped
    Iris pseudacorus (yellowflag iris) infestation. Photo: Bob Case
    Iris pseudacorus_seed pods_RonVanderhoff
    Iris pseudacorus (yellowflag iris) seed pods. Photo: Ron Vanderhoff