Iris pseudacorus

Iris pseudacorus_yellowflag iris flower_ JM Di Tomaso
Photo courtesy 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.

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.
  • California distribution map - Maps based on survey data from county Weed Management Areas.
    These maps are the product of those working in the field and are not intended to be definitive.

Other Resources

Symposium Presentations

  • Connick, S. and M. Gerel (2004). Partnering to prevent invasions of plants of horticultural origin. California Invasive Plant Council Symposium 2004. Ventura, CA.

Cal-IPC News Articles

  • 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.
  • Kelly, M. (1999). Roundup of Arundo projects reveals commitment, strategic weakness. CalEPPC News. 7: 4-9.