Yellow Flag Iris (Iris pseudacorus)

Highly invasive plant; Yellow Flag Iris found at Summit Lake

While conducting field work this summer, wildlife biologist Jakob Dulisse discovered a small patch of invasive Yellow Flag Iris (iris pseudacorus). He immediately took action dug out the plant, disposed of it properly and reported the sighting to the Central Kootenay Invasive Species Society (CKISS).

CKISS has listed Yellow Flag Iris as a priority action species in the Nakusp region and must be controlled immediately because it is capable of invading new areas quickly because it can spread by seeds and rhizome fragments.  Once established it outcompetes native plant species and ultimately disrupt an area’s ecosystem complexity. These disturbances result in reduced habitat suitability and support for wildlife – especially for breeding, staging, and migrating waterfowl. In addition, the plant can sicken livestock if ingested and can cause skin irritation in humans.

Yellow Flag Iris is a “wet-footed” plant that grows in ponds, ditches, wetlands and other riparian areas. From May to July Yellow Flag Iris is easily recognizable, with a pale yellow flower that resembles a garden iris. Over the past four years, the CKISS has conducted invasive plant surveys on Summit Lake; however, they still heavily rely on reports from the public.

Yellow Flag Iris Infestation

Unless there is a drastic change our funding for aquatic invasive species surveys will be limited going forward, therefore reports of invasive species in our region, like the Yellow Flag Iris are vital in protecting our waters from the harmful impacts of invaders. Prevention is the best tool in our toolbox to stop the spread of invasive species and next in line is early detection and rapid response. We urge folks to visit our website ( in order to educate themselves on how to ID and report high priority invasive species in their communities” states CKISS Education Program Coordinator Laurie Frankcom.

How did Yellow Flag Iris get there in the first place? The invasive plant was introduced through the horticulture industry when gardeners planted it into their water gardens. It has now “jumped the garden fence” and ended up in natural areas causing environmental harm. CKISS is an active ambassador for the provincial-wide PlantWise program.  PlantWise was designed to educate and motivate both the horticulture industry and home gardeners to choose safe alternatives or native plants instead of invasive ones.Plantwise Logo