An invasive aquatic that grows in groups,
Each plant spreading further along through my roots,
With 3 yellow petals and slender, long leaves,
I stand out from Cattails along rivers and streams!
I Spy in the Sea to Sky…
Native to Europe, Africa, and Asia, this plant has made its mark as an ornamental plant in gardens worldwide due to its beautiful and bright yellow flowers. Can you guess what it is?
It’s Yellow Flag Iris (Iris pseudacorus)! It produces vivid yellow flowers from May to July, and likes to grow near water bodies. Be sure to watch for it near marshes, lake shorelines and stream banks. Yellow Flag Iris is a high-priority plant in the Sea to Sky. We aim to eradicate it from the region, as per SSISC’s priority plant species list.
Yellow Flag Iris can be easily identified by several distinctive features:
- Sword-shaped leaves that grow in a fan-like display up to one meter in height.
- Iconic yellow flowers have six petals, with slight purple-brown veining.
- Orange (turmeric) coloured rhizomes that grow underneath the ground in dense mats.
How do I differentiate it from other irises or native plants?
Did you know that Yellow Flag Iris is the only entirely yellow iris found in North America? If you see a bright yellow iris, chances are you’re looking at Yellow Flag Iris. Its leaves also have a distinctive mid-rib that many other irises do not have. You should be able to feel the mid-rib under your thumb.
This invasive plant is often confused with the native Cattail (Typha latifolia).
- Cattail has round stems and is taller than Yellow Flag Iris.
- The base of Yellow Flag Iris plants has a purple tinge, but Cattail does not.
- Yellow Flag Iris stems grow in a fan shape, whereas Cattail stems are round and grow in a honeycomb-like structure.
If you’d like to learn more, you can refer to the Fraser Valley Invasive Species Society’s guide to help you tell Yellow Flag Iris and Cattail apart.
Why is Yellow Flag Iris such a concern in the Sea to Sky?
Yellow Flag Iris is a highly resilient, toxic plant with no natural predators in our area. Its ability to reproduce both vegetatively and through seeds makes it an aggressive spreader. As it tends to grow near water bodies such as rivers or streams, its seeds and pieces of rhizomes (roots) can spread long distances via watercourses, and invade new areas further downstream.
Yellow Flag Iris outcompetes native species and takes over prime growing areas, which reduces food availability for native animals that graze. This invasive plant is also toxic to humans and livestock.
Left unchecked, this plant forms dense mats that trap sediment, thereby choking natural waterways, irrigation canals and flood control ditches that are important in infrastructure and agricultural areas.
If you want to know what you can do to help, read more about Yellow Flag Iris on its species profile page.
I Spy in the Sea to Sky Contest
Guess the invasive species in our I Spy in the Sea to Sky weekly social media post, June through August, to enter our giveaway.
At the end of each month, one lucky commenter will win a native wildflower seed mix packet! Follow us and comment on social media to participate!
CONTEST RULES:
- Comment your guess (common or species name) on the social media post (on Instagram or Facebook) to enter. Only correct guesses will qualify you for the giveaway.
- One entry per person per post.
- Anyone can play, but only Sea to Sky region residents can win.
- Entries will close at 11:59 PM PST on June 30th, 2024.
- Winners will be announced in the first week of July in an Instagram story AND contacted directly via their platform of entry.
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