Iris pseudacorus L.
yellow iris (paleyellow iris)
Iridaceae (Iris family)

Introduction to Vascular Plants


© Ernie Sellentin     (Photo ID #1181)


E-Flora BC Static Map

Distribution of Iris pseudacorus
Click here to view the full interactive map and legend


Yellow iris is an introduced invasive species that is native to Europe, western Asia and northwest Africa. Outside its native range, it is a significant invader in freshwater and brackish cattail marshes and spreads in marshes and adjacent areas by underground rhizomes and seeds. In North America, it is now found in many US states (AL, AR, CA, CT, DC, DE, FL, GA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, NE, NH, NJ, NV, NY, OH, OR, PA, RI, SC, TN, TX, UT, VA, VT, WA, WI, WV) and Canadian provinces (BC, MB, NB, NF, NS, ON, PE, QC) (USDA 2010). In BC, it is found in the southern part of the province, where it occurs in marshes, ditches, sloughs, streambank and pond edges. It is a favourite plant in water gardens and artificial ponds because of its bright yellow flowers.

Species Information

Perennial herb from a thick rhizome; flowering stems usually simple, sometimes branched, 50-150 cm tall.
Mostly basal, linear-lanceolate, 50-90 cm long, 1-3 cm wide, entire, the tips long-pointed.
Inflorescence of (2) 4 to 12 showy flowers on stout, 2- to 5-cm long stalks; flowers pale to deep yellow, the tubes flared above, 1-1.5 cm long; petals erect, narrowed at the middle, about 2-3 cm long, 4-8 mm wide, the bracts herbaceous, the margins translucent; sepals broadly rounded, 5-7.5 cm long, 2-3 cm wide, bent back; style branches 2-2.5 cm long, the crests less than 1/2 as long; stigmas rounded.
Capsules, cylindrical, 4-8 cm long; seeds numerous.

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.


Ecological Framework for Iris pseudacorus

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres)
188 30 346
Slope Gradient (%)
1 0 2

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

110 110 110
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 5 6
Modal Nutrient Regime
# of field plots
 species was recorded in:
Modal BEC Zone Class

All BEC Zones (# of stations/zone) species was recorded in

CDF(1), IDF(1)

Habitat and Range

Moist ditches, sloughs, marshy meadows and streambanks in the lowland and steppe zones; frequent garden escape in S BC; introduced from Europe.

SourceThe Illustrated Flora of British Columbia

Taxonomic Notes

This species is listed by the Greater Vancouver Invasive Plant Council of the twelve most problematic species in the Vancouver region. For further information about control of this species, visit their web site. It is also listed as one of the top fourteen species of concern by the Coastal Invasive Plant Committee. Visit their web site.