Plant Assessment Form

Iris pseudacorus

Synonyms: Iris acoriformis, Iris bastardi, Iris curtopetala, Iris lutea, Iris paludosa

Common Names: yellowflag iris; pale yellow iris

Evaluated on: 8/5/04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

Mark Newhouser/Project Director, Arundo Eradication & Coordination Program
Sonoma Ecology Center
205 First St West Sonoma, CA 95476
(707) 996-0712 ext.103
mnewhouser@vom.com

List commitee members

Joe DiTomaso
Cynthia Roye
Peter Warner
Jake Sigg
Alison Stanton
John Randall

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Impact?
Four-part score UBCD Total Score
C
1.2 ?Impact on plant community B. Moderate Other Published Material
1.3 ?Impact on higher trophic levels C. Minor Other Published Material
1.4 ?Impact on genetic integrity D. None Observational
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
12 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly Observational
2.3 ?Recent trend in total area infested within state C. Stable Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Observational
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Observational
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Distribution?
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? U Reviewed Scientific Publication
Identify ecosystem processes impacted:

unknown


Sources of information:

no information


Question 1.2 Impact on plant community composition,
structure, and interactions?
B Other Published Material
Identify type of impact or alteration:

Displaces native vegetation in natural wetland and riparian areas. Can reproduce vegetatively and by seed. Is toxic if eaten in quantities by wildlife or livestock.


Sources of information:

Question 1.3 Impact on higher trophic levels? C Other Published Material
Identify type of impact or alteration:

Lessens habitat and food sources for native wildlife. Displaces native vegetation, reducing food and habitat for native animal species. Is toxic if eaten in quantities by wildlife or livestock.


Sources of information:

Question 1.4 Impact on genetic integrity? D Observational

No known hybridization. Never heard of any hybridization. Most native species don't exist in the same habitat.


Sources of information:

Observational, Jake Sigg, Joe DiTomaso, 2004.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
B Observational
Describe role of disturbance:

Anthropogenic disturbance such as irrigation ditches and disturbances such as grazing allow for dense stands of the Yellowflag Iris to form. Disturbance seems to allow for and increase the rate of establishment.


Sources of information:

Question 2.2 Local rate of spread with no management? B Observational
Describe rate of spread:

Spreads but does not double in less than 10 years.


Sources of information:

Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Question 2.3 Recent trend in total area infested within state? C Observational
Describe trend:

Statewide population remaining stable.


Sources of information:

Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Question 2.4 Innate reproductive potential? A Observational
Describe key reproductive characteristics:

See table. 7 points.


Sources of information:

Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Question 2.5 Potential for human-caused dispersal? B Other Published Material
Identify dispersal mechanisms:

Used in landscaping and has escaped cultivation in certain areas. Has been naturalized in California at a number of wet locations. Still sold horticulturally.


Sources of information:

Question 2.6 Potential for natural long-distance dispersal? C Observational
Identify dispersal mechanisms:

Sources of information:

Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

It occurs in Oregon, Washington, Idaho, Montana, Utah, Nevada, and in California in the San Francisco Bay Area, San Joaquin Valley, and the Central and Southern Coast. It also occurs in eastern, southern, and most central states. Invades many wet ecosytems.


Sources of information:

Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Other Published Material

No information on date or state of introduction. Native to western Europe and North Africa. Yellowflag Iris invades wet areas including riparian areas, wetlands, meadows, and ponds. It has potential to invade similar ecosystems in different states. Exists in 2 major and 3 minor ecotypes in CA.


Sources of information:

DiTomaso J.M., Healy E. Weeds of California and Other Western States. As yet unpublished.
DiTomaso, J. M., Healey E. A. ÐAquatic and Ripirian Weeds of the West.Ó 221-223. 2003
Fuller, T.C., McClintock E. Poisonous Plants of California. 1986
Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Question 3.2 Distribution/Peak frequency? D Observational
Describe distribution:

Occupies less than 5% of the wetland areas in CA.


Sources of information:

Observational, Jake Sigg, Peter Warner, Joe DiTomaso, John Randall, 2004.


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually Yes
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 7
Total unknowns: 1
Total score: A?

Related traits:

Does spread by seed and vegetatively. Grazing encourages establishment by increasing disturbance and animals won't eat the iris due to it's toxicity.

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirsD, < 5%
Aquatic Systemsrivers, streams, canalsD, < 5%
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampD, < 5%
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest
  • Modoc Plateau
  • Mojave Desert