Yellow flag iris
Iris pseudacorus · Aquatic plants
Flowers or seeds · Photo: Ana Luz Della Costa / CC BY
Also called Yellow iris, Pale yellow iris, Water flag
State noxious weed listing
- Idaho: Containment
- Oregon: B list
How to identify Yellow flag iris
- Sword shaped leaves in flat fans
- Large yellow iris flowers in May and June
- Thick pinkish rhizomes
- Large three sided seed pods
Similar plants
Cattails and burreed have no fans of leaves; native irises are blue and grow in meadows.
Growth profile
| Growing season | Leaves green up early in spring, flowers May and June, seed pods in late summer and leaves stay green late into fall. |
|---|---|
| Starts growing | About 45 to 50 F soil |
| Light | Full sun to shade |
| Depth | Moist shoreline to about 1 foot of water |
| How it spreads | Rhizomes and floating seeds |
| Habitat | Shorelines, marshes, ditches and slow streams; tolerates salt and low oxygen soils. |
Why it matters in a lake
All parts are toxic to livestock and the sap irritates skin. Floating rhizome mats and seeds spread it along shorelines. Listed noxious in Idaho and Oregon.
Where it is found
- Idaho: Occasional
- Oregon: Common
- Wyoming: Rare
Classification
| Kingdom | Plantae |
|---|---|
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Asparagales |
| Family | Iridaceae |
| Scientific name | Iris pseudacorus |
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Western water hemlock
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Baltic rush
Common spikerushNeed a hand?
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