Yellowflag Iris

Aquatic perennial 3+ft. Erect along shorelines and stream banks, can survive on drier sites. Leaves: Basal leaves broad flat, sword-shaped. No stalks, Upper leaves smaller. Stems: Single branched. Flower: Yellow downward sepals with dark (purple) streaks, 2-4” across, few to several on stem. Roots: Fleshy rhizomatous. Reproduction: Seeds: Formed in 3 sided pods, each pod produces up to 30 flat brown seeds. Vegetative: Rhizomes fragments which break easily.

Toxic to wildlife and livestock.

Native to Eurasia. Introduced to North America as an ornamental. In Teton County, yellowflag iris is found on ditches across the county. Some locations were intentionally introduced prior to the species being declared noxious. These locations were reported to TCWP by the landowners, and TCWP and these landowners work together to remove these plants and prevent further spread.