Species PlantsYellow Flag Iris

Yellow Flag Iris

Iris pseudacorus

CommonPlant
Illustration of Yellow Flag Iris (Iris pseudacorus)
Safety note: All parts are toxic if ingested; sap can cause skin irritation.

Yellow Flag Iris is a striking wetland iris originally from Europe that has naturalized widely across North American waterways. Its bright yellow flowers are held above sword-like leaves in late spring, and it spreads aggressively along stream banks and pond margins through thick rhizomes. While beautiful, it can crowd out native vegetation and is considered invasive in many regions.

Habitat
Pond margins, stream banks, marshes, and wet ditches across much of North America
Diet
Flowers visited by large native bees; not typically browsed by wildlife
How common
Common

Best time to see a Yellow Flag Iris

The best time to see a Yellow Flag Iris is April–May, when about 65% of U.S. sightings happen, based on 21,426 research-grade iNaturalist observations.

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