Species Iris Group of North America

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March 2015

Iris pseudacorus

Iris pseudacorus has become problematic across North America. This Eurasian species rapidly colonizes suitable habitats and outcompetes the pre-existing native species. States & provinces have been enacting legislation to slow its spread. SIGNA is trying to keep up with these new laws so we can share the information here with you.

These photos show a forested wetland habitat in southwestern Ohio where Iris brevicaulis once thrived but Iris pseudacorus now dominates. It's disheartening to see a formerly pristine habitat heavily degraded by one exotic species. But this is what happens, and has been happening across North America, when Iris pseudacorus escapes cultivation. And this is why so many localities are outlawing the sale, trade, and cultivation of it.

Although it is the northern regions that are passing these legislations, Iris pseudacorus is equally troublesome in the deep south. Along the gulf coast the warm climate hinders the ability of the species to bloom. But it still aggressively spreads vegetatively and chokes out areas just as it does in the north. This means even sterile hybrids are dangerous to cultivate. Should any of them escape into wild areas the consequences could be just as damaging.

Local legislation continues to be passed against Iris pseudacorus across the U.S.A. and Canada in response to its harmful impact in wild natural areas. As of February 2018 it is illegal to buy, sell, or possess in 14 states and provinces. This includes subspecies, variants, named cultivars, and hybrids. 30 other states and provinces officially recognize & designate it as a harmful invasive species, have eradication programs in place, and actively discourage its cultivation. Continued monitoring in these locations may result in it becoming banned there as well. Please take proper care if you live in these regions.

This information was compiled in January and February of 2018. If a state or province is not listed, there is no official legislation or warning against Iris pseudacorus from that government. The web links and legal status will change over time. To get the latest information for a specific location you should do a Google search using key words like: 'Iris pseudacorus Alberta prohibited' or 'Iris pseudacorus Alberta invasive list' or 'Iris pseudacorus Alberta banned'. Most states and provinces also have a list of regulated and banned invasive species which you could Google search.

LocationStatusNotes & Evidence
AlaskadiscouragedNot illegal, but scores 66/100 threat level for invasivness in the southern coastal region.

http://accs.uaa.alaska.edu/files/invasive-species/Iris_pseudacorus_BIO_IRPS.pdf

Albertaprohibited"Do not grow or purchase this plant."

http://canadainvasives.ca/initiatives/national-horticulture-outreach-network/canadas-top-10-most-important-invasive-horticultural-plants/

British ColumbiaprohibitedProhibited, listed as a provincially regulated noxious plant.

http://bcinvasives.ca/invasive-species/about/regulated-invasive-species-in-bc/list-of-regulated-invasive-plants-in-bc/

CaliforniadiscouragedA bad weed in wetlands in California. Deserves a “B” rating as it has invaded many areas to which it is adapted and undoubtedly has the ability to spread further. Because of this potential future harm, a “B” rating is justified.

http://blogs.cdfa.ca.gov/Section3162/?p=3591

ColoradodiscouragedNot illegal, but on the offical watch list as potentially invasive species.

https://www.colorado.gov/pacific/agconservation/noxious-weed-species

ConnecticutprohibitedNo person shall import, move, sell, purchase, transplant, cultivate or distribute it.

https://www.cga.ct.gov/2004/act/Pa/2004PA-00203-R00SB-00547-PA.htm

DelawarediscouragedNot illegal, but one of the top invasive species in the state.

http://www.dnrec.delaware.gov/fw/NHESP/Documents/Non-native%20and%20Invasive%20Plants%20of%20Delaware%202016.pdf

FloridadiscouragedNot illegal, but officially discouraged from cultivation.

http://plants.ifas.ufl.edu/plant-directory/iris-pseudacorus/

IdahodiscouragedRecognized as a noxious weed and is on state's containment plan list.

http://invasivespecies.idaho.gov/terrestrial-plants

IllinoisprohibitedDesignated as an injurious invasive species, it is now illegal to buy, sell, or transport this species in Indiana and Illinois.

http://www.iiseagrant.org/ais/aqpl_trade.php

IndianaprohibitedDesignated as an injurious invasive species, it is now illegal to buy, sell, or transport this species in Indiana and Illinois.

http://www.iiseagrant.org/ais/aqpl_trade.php

KansasdiscouragedNot illegal, but being considered for addition to the watch list as potentially invasive species.

https://agriculture.ks.gov/docs/default-source/pp-weed-reports-2017/noxious-and-invasive-weed-update---spring-2017.pdf?sfvrsn=0

KentuckydiscouragedNot illegal, but officially discouraged from cultivation.

https://efotg.sc.egov.usda.gov/references/public/KY/Invasive_Advisory_List.pdf

LouisianadiscouragedNot illegal, but officially urges the use of native Louisiana Iris species instead.

http://www.wlf.louisiana.gov/sites/default/files/pdf/page_wildlife/32937-Wildlife%20Action%20Plan/18_chapter_6.pdf

MaineprohibitedProhibited since January 2017, illegal to sell, import, export, buy or intentionally propagate.

http://www.maine.gov/dacf/php/horticulture/documents/InvasivePlantListHandout.pdf

ManitobadiscouragedNot illegal, but officially discouraged from cultivation.

http://canadainvasives.ca/initiatives/national-horticulture-outreach-network/canadas-top-10-most-important-invasive-horticultural-plants/

MarylandprohibitedTier 1 Invasive, as of April 11, 2017 you cannot propagate, import, transfer, sell, purchase, transport, or introduce any Tier 1 invasive plant into Maryland.

http://agrisk.umd.edu/blog/new-regulations-on-invasive-plants-in-maryland-go-into-effect

MassachusettsprohibitedBanned from importation, propagation, sale, trade, and distribution.

https://www.mass.gov/service-details/prohibited-plant-list-background

MichigandiscouragedProhibited in 2005 but later lifted, this is still considered a threat to Michigan wetlands however it is not currently listed as a banned or restricted species.

http://www.michigan.gov/invasives/0,5664,7-324-68002_74282---,00.html

MinnesotaprohibitedRegulated invasive species that is not legal to possess, sell, buy, and transport.

http://www.dnr.state.mn.us/invasives/laws.html

MontanadiscouragedNoxious weed, on state's list for containment & eradication. See video below.

https://www.mtweed.org/weed_id/yellowflag-iris/

http://www.msuinvasiveplants.org/documents/mt_noxious_weeds/yellowflag_iris.pdf

NebraskadiscouragedNot illegal, but state has ongoing eradication efforts in place to remove established invasive populations. See video below.

http://www.neweed.org/documents/watchlist.pdf

https://neinvasives.com/species/plants/yellow-flag-iris/

New BrunswickdiscouragedNot illegal, but included on New Brunswick's Top 10 Unwanted Invaders species list.

http://www.nbala.ca/invasive-plant-patrol-program/

New HampshireprohibitedNo person shall collect, transport, import, export, move, buy, sell, distribute, propagate or transplant any living and viable portion of any plant species, which includes all of their cultivars and varieties.

https://www.agriculture.nh.gov/publications-forms/documents/prohibited-invasive-species.pdf

New JerseydiscouragedNot illegal, but recently proposed for addition to the state's DO NOT PLANT list.

http://www.princetonnj.gov/res-16-364-invasive-plant-species.pdf

New YorkprohibitedCannot be knowingly possessed with the intent to sell, import, purchase, transport or introduce. In addition, no person shall sell, import, purchase, transport, introduce or propagate prohibited invasive species.

http://www.dec.ny.gov/docs/lands_forests_pdf/isprohibitedplants2.pdf

North CarolinadiscouragedNot illegal, but officially discouraged from cultivation.

http://ncbg.unc.edu/plants-to-avoid/

OhiodiscouragedNot illegal, but listed as a well-established invasive posing moderate to severe threat to Ohio's natural areas.

http://ohiodnr.gov/portals/0/pdfs/invasives/ohio-invasive-plants-r0400.pdf

OklahomadiscouragedNot illegal, but on the offical watch list as potentially invasive species.

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-9863/NREM-2895web.pdf

https://www.wildlifedepartment.com/wildlifemgmt/swg/T44P1.PDF

OntariodiscouragedNot illegal, but officially discouraged from cultivation.

http://canadainvasives.ca/initiatives/national-horticulture-outreach-network/canadas-top-10-most-important-invasive-horticultural-plants/

OregondiscouragedClass B noxious weed, quarantine required.

https://www.portlandoregon.gov/bes/article/197414

PennsylvaniadiscouragedNot illegal, but listed as a Rank 2 - Significant Threat species.

http://www.docs.dcnr.pa.gov/cs/groups/public/documents/document/dcnr_20033302.pdf

Prince Edward IslanddiscouragedNot illegal, but a priority species for monitoring on PEI Invasive Species Spotter’s Network.

http://peiinvasives.ca/yellow-flag-iris

QuebecdiscouragedNot illegal, but officially discouraged from cultivation.

http://canadainvasives.ca/initiatives/national-horticulture-outreach-network/canadas-top-10-most-important-invasive-horticultural-plants/

Rhode IslanddiscouragedNot illegal, but recognized as a well established invasive species in the state.

https://www.anstaskforce.gov/State%20Plans/RI_SMP_Approved.pdf

SaskatchewandiscouragedNot illegal, but officially discouraged from cultivation.

http://canadainvasives.ca/initiatives/national-horticulture-outreach-network/canadas-top-10-most-important-invasive-horticultural-plants/

South CarolinadiscouragedNot illegal, but officially discouraged from cultivation.

http://ncbg.unc.edu/plants-to-avoid/

TennesseediscouragedRanked as significant threat, not illegal, but officially discouraged from cultivation.

http://tnipc.org/invasive-plants/plant-details/?id=133

VermontprohibitedDesignated as a Class B noxious weed, prohibits the importation, movement, sale, pocession, cultivation and/or distribution of this species.

http://agriculture.vermont.gov/plant_pest/plant_weed/invasive_noxious_weeds/noxious_weeds_list

VirginiadiscouragedHighest tier invasive, not illegal, but officially discouraged from cultivation.

http://www.dcr.virginia.gov/natural-heritage/document/nh-invasive-plant-list-2014.pdf

WashingtondiscouragedClass C noxious weed, can be designated illegal at county-level.

https://www.nwcb.wa.gov/images/weeds/Yellow_flag_iris.pdf

West VirginiaprohibitedTier 1 Invasive, Illegal to sell, transport, etc., without a permit which addresses environmental safety.

https://efotg.sc.egov.usda.gov/references/public/WV/PlantPestAct.pdf

WisconsinprohibitedFormerly restricted, now prohibited as the restricted phase-out period expires in 2018.

http://dnr.wi.gov/topic/invasives/documents/nr40plantlist.pdf



All Iris pseudacorus photos by Dennis Kramb.

© 2018, SIGNA. For general inquiries about SIGNA please contact krw25@cornell.edu. Please report technical problems to dkramb@badbear.com.