Yellow Flag Iris
Iris pseudacorus
Information Sheet (PDF)
List A - Eradication Required
General
- Family: Iridaceae
- Introduced from: Europe and North Africa
- An escaped ornamental
Habitat
- Found in wetlands, along the edges of water bodies and waterways
Lifecycle
Growth form
Plant
Vegetation
- Plant 3-6 ft tall
- Leaves overlap at the base, 35 in long and 1.25 in wide, sword shaped, dark green with a thickened middle
- Usually 10 leaves per plant
Roots
- Rhizomes form a “root ball” which can be several feet long and wide
Flower
- May-July
- Bright yellow
- 3 upward curved petals and 3 downward curved sepals with brown to purple streaks
- Multiple flowers along stem
Seed
- Angled seedpods up to 3 in long
- Up to 120 seeds per pod
Reproduction
Similar Species
Impacts
Can crowd out native species and form large monocultures
Habitat and Distribution
- General requirements: Wet habitat
- Distribution: Limited in certain areas throughout Colorado and in Jefferson County
Control
Biological
Chemical
Cultural
- Prevention - do not purchase, do not plant
- Removal - Cut and bag flowers, dispose of in the garbage. Do not compost
Mechanical
- Burning - N/A
- Grazing - N/A
- Mowing - N/A
Use all chemicals according to the manufacturer’s label. No specific recommendation or endorsement is made or implied by listing methods or products.
Colorado Department of Agriculture - Yellow flag iris
Montana Weed Control Association - Yellow Flag Iris Video
USAD - Plants Profile for Iris pseudacorus (paleyellow iris)
