Yellow flag iris
Discuss this plant with the guide — choose this profile as a possible match and prepare your observations for Colorado Plants & Practical Care.
Iris pseudacorus
Colorado noxious weed · List A — Eradicate. CO-rules-2025
Uncommon in Colorado. All populations are designated for eradication statewide. This is a management category, separate from danger ratings. Category source · What the lists mean.
Ingestion concern; invasive wetland colonies. Exposure help.
Still researching this plant
This is a sourced working profile. The cited findings are available below. Independent botanical and veterinary review is pending. Uncertainty is not a finding that the plant is safe.
Three views of this plant
Source-identified reference photographs; these are not a complete identification key. A source location outside Colorado does not establish local occurrence.
Kailey Alderfer · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Kailey Alderfer · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Kailey Alderfer · CC BY 4.0
Photo source and identification
Original record · Original image
Source scientific identification plus visual morphology review of the selected photograph. This is a source-identified reference image, not a specimen-based taxonomic determination.
iNaturalist large server-resized image; no local crop, colour change, or generative editing. Gallery display preserves the full image; the catalog preview uses a CSS crop.
Recognize
Yellow iris flowers rise among upright, sword-shaped leaves along wet ground or shallow water. N-iris-pseudacorus
Plants & habitat
Seeds and rhizomes can create dense colonies that displace wetland plants. N-iris-pseudacorus
People
Ingestion can cause gastrointestinal symptoms. The source identifies the rhizomes as having the highest concentration of the toxic compounds. N-iris-pseudacorus
Dogs & cats
NC State flags both dogs and cats; prevent chewing or digging up rhizomes and obtain veterinary advice after ingestion. N-iris-pseudacorus
Other animals
The source also flags horses, without establishing a safe feeding amount. N-iris-pseudacorus
Before taking action
Confirm identification and the requirements of your county weed program. For chemical treatment, follow the current product label, including restrictions around animals and water. S27
This is a statewide eradication priority. Contact your county weed program promptly for identification and an approved management and disposal plan. CO-rules-2025
References
- CO-rules-2025 — Colorado Noxious Weed Act rules, 8 CCR 1206-2, Colorado Secretary of State / Department of Agriculture. Accessed 2026-09-07T01:07:48+00:00. Locator: Parts 3.1, 4.1, 5.1; management provisions; effective May 15, 2025.
- N-iris-pseudacorus — iris pseudacorus — Plant Toolbox, NC State Extension. Accessed 2026-09-07T01:04:53+00:00. Locator: Description; Attributes; Problems; Poisonous to Humans.
- S27 — 2103 – Colorado Noxious Weeds, PlantTalk Colorado · CSU Extension. Accessed 2026-09-07T00:23:57+00:00. Locator: List A, B and C management categories.