HomeMy WebLinkAboutYellow Flag Iris.pdf
Yellow flag‐iris in shallow water Flowers in bloom Seed pods
Maple Ridge Noxious Weeds Program
Yellow Flag‐Iris
(Iris pseudacorus)
Designation: Provincially Noxious
History:
Native to the UK, Western Asia, North Africa
and the Mediterranean, it has become
established and spread quickly in wetlands
and along roadsides throughout North
America.
How to Identify:
Size: Perennial herb, growing to 1.5 m tall
Flowers: Yellow flowers blooming from May
to July have 3 small slender petals facing up
and 3 larger ones hanging down.
Leaves: 0.5 ‐ 1.5 m long, slender, fleshy,
sword‐shaped with a distinctive ridge in the
mid‐vein. Dark green to blue/green and may
remain green during mild winters
Location: Most commonly found growing in
ditches, irrigation canals, marshes, and
margins of lakes, ponds and slow‐moving
rivers in water up to 25 cm deep. Prefers part
shade or full sun exposure.
Mistaken Identity: Can be confused with
yellow bearded iris, or, when not flowering,
bulrush or bur‐reed.
Danger / Impact
Colonizes and spreads in dense stands, out‐
competing native wetland plants and reducing
resources available for wildlife.
Plant roots can alter waterways by
compacting soil, trapping sediments and
increasing elevation.
Very difficult to eradicate once established.
Dispersed by broken rhizomes and seeds.
Seed pods are buoyant and can remain afloat
for up to 7 months, allowing it to spread very
long distances.
Management:
As this species is easily spread and difficult to eradicate, the
first priority should be to deplete future seed resources by
removing all flowers and seed heads.
For small populations, dig up and remove manually. For
large populations, clip seed heads off to prevent further
spread. Cut plant materials close to the ground and clean
debris away. Expose rhizomes and cut to their full depth in
10 – 15 cm strips using a sharp tool such as a mattock.
Remove the strips with the mattock or a crow bar ensuring
that you go the full depth of the plant (up to 30 cm deep).
Caution: All plant parts are poisonous (contact causes skin
irritation; ingestion causes nausea; wear gloves!)
Disposal: The best option is to place all plant parts in
garbage bags labelled “invasive species” and take to the
landfill. Do not compost as flowers can still form viable seeds
after removal.
Follow‐up: Address any recently sprouted seedlings in the
summer (July) and monitor regularly for re‐growth. Remove
any new plants that appear.
Restoration and Planting Alternatives:
Plant native or non‐invasive species including:
Native Plants:
Hardhack (Spiraea douglasii)
Red‐osier dogwood (Cornus stolonifera)
Willow species (Salix spp.)
Common bulrush (Typha latifolia)
Non‐Native Plants:
Blazing star (Liatris spicata)
Tall delphinium (Delphinium elatum)
Bloody iris (Iris sanguinea)
Hardhack (Spiraea douglasii)
Spike speedwell (Veronica spicata)
Yellow Bearded Iris – A non‐invasive garden
iris easily mistaken for Yellow Flag‐Iris.
Distribution in DMR:
Small groups of plants found in only a few areas.
Who Do you Call?
1) REPORT PROHIBITED WEEDS – Report‐A‐Weed: www.reportaweedbc.ca 1‐888‐WEEDSBC
2) DMR: 604‐467‐7363 – AND SEE: http://www.mapleridge.ca/714/Invasive‐Plant‐Species
Information and photos:
http://www.saanich.ca/living/environment/pdf/invasive/yellow‐flag‐iris‐alert‐web.pdf
http://www.bcinvasives.ca/invasive‐species/invasive‐plants/yellow‐flag‐iris
http://iscmv.ca/target‐species/species‐profiles