Tag Archives | priority


August’s Weed of the Month: Puncturevine

Puncturevine (Tribulus terrestris) is aptly named! This invasive weed has spiny seed heads that can easily puncture a bike tire, inflatable raft, animal paw, or footwear. Be on the lookout because it is beginning to make its way into Clackamas County from eastern and southern Oregon. Also known as “goathead”, puncturevine is native to southern […]

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June’s Weed of the Month: Policeman’s Helmet

Policeman’s helmet (Impatiens glandulifera) is an invasive weed which grows in ditches, wetlands, and along waterways. Native to India, this fast-growing annual was introduced as a ornamental plant due to its impressive growth and the showy purple, pink or white blooms. Since introduction, it has escaped cultivation to become the dominate riparian vegetation in many […]

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Orange hawkweed in bloom

May’s Weed of the Month: Orange Hawkweed

Orange hawkweed (Hieracium aurantiacum) is a relatively new invasive weed in Clackamas County.  With your help, our team plans to keep it from becoming a common problem for landowners! A member of the sunflower family, orange hawkweed is native to central and southern Europe and grows in open areas like gravel pits, roadsides, meadows, pastures, […]

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April’s Weed of the Month: Garlic Mustard

Garlic mustard (Alliaria petiolata) is an increasingly invasive weed in our community.  Native to central and western Europe, this fast-growing plant commonly invades sites such as parks, trails, roadsides, and streamsides. April is a great time to manage this priority invasive weed on your property. Sometimes referred to as Jack-by-the-hedge, garlic mustard is easily identified […]

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Garden loosestrife (Lysimachia vulgaris)


Common names:

Garden loosestrife, garden yellow loosestrife,

Scientific Name:

Lysimachia vulgaris


Garden loosestrife is a tall upright rhizomatous noxious weed that grows up to 5 feet in height.  It is characterized by terminal panicles of bright yellow 5-petaled flowers.  Leaves are opposite to whorled, nearly sessile and lanceolate 7-12 cm in length.  The stems and leaves are soft and hairy.  Flowered are ringed by distinctive orange-margined green sepals. Underground rhizomes can spread to lengths up to 15 feet.  Plants reproduce from both rhizomes and seeds.

Life cycle:


Height of mature plants

3 to 6 feet

Flower color:

Yellow 5- petaled flower, that lack reddish or black streaks or dots

Bloom time:

Typically blooms during July and August.


The closely related Yellow loosestrife (Lysimachia punctata) is a less aggressive garden ornamental, with lower flowers from emerging from the leaf axils, and the yellow flowers lack the orange-margined sepals, characteristic of the noxious garden loosestrife.


Garden loosestrife is found escaping in wetlands and along streams and river.  It is also likely to be found in garden setting.  This species is known to occur in only one location in Oregon.


Garden loosestrife invades wetland and riparian areas, where it displaces desirable native vegetation.  Once established it can spread rapidly, and has been known to displace very hearty plants such as cattails.  Invasion by garden loosestrife disrupts habitat for fish and wildlife, and can limit recreation opportunities in highly invaded sites.

Noxious Weed Listing:


This species is native to Europe.

Present in Clackamas County:



Oregon Noxious Weed Profile

USDA Plants

King County Noxious Weed Program

Invasive Plant Atlas of New England



Working Together

The old adage “many hands make light work” could not be truer when it comes to weed management. The WeedWise Program routinely works with a number of partnering entities and organizations across our region to combat invasive weeds.  This include local, state, and federal agencies as well local non-profits and watershed councils. Our partnerships also […]

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What are weeds?

There are a whole host of terms to describe weeds.  The term “weeds” itself can refer to any plant that occurs in an undesirable location. Terms like “non-native“, “exotic“, “alien” or “non-indigenous” refer to plants that occur in areas where they historically did not occur.  These terms make no distinction whether plants are desirable or undesirable.  The term “invasive” refers to a plant or animal that exhibits aggressive growth and displace other species.  Other terms like “noxious” or “nuisance” refer to plants that have special designation by the state or by a municipality the prohibits their sale or cultivation.  With this broad diversity of terms, it is no wonder that many people find themselves confused and wondering how to make sense of it all.

At the WeedWise program, we hope to clarify this issue by focusing on plants we refer to as “invasive weeds”Invasive weeds are plants that live outside their historic geographical range, and whose aggressive growth habit has a detrimental effect on our social, economic, or ecologic resources.  The three key components of invasive weeds are that they:

  1. Did not historically occur in our area, but have been brought in either intentionally or unintentionally through human action.
  2. Exhibit aggressive growth which displaces native or desirable vegetation, and will continue to spread unless actively controlled.
  3. Have a negative impact on our community.

These three characteristics clarify invasive weeds as those plants that pose the greatest threat to our community.  By focusing on invasive weeds the WeedWise program is working to maximize its limited resources to realize the greatest benefit to Clackamas County.

Defining our priorities

All invasive weeds pose a major threat to the residents of Clackamas County, but some of these pests can be more damaging than others.  In addition, the costs to control these invasive weeds greatly exceed the resources available for their management.  As a result, the WeedWise program has prioritized its efforts to target invasive weeds that pose the greatest risk, have the greatest negative impact, and may still be limited enough in their distribution to allow for eradication or containment in Clackamas County.  For these “priority” invasive weeds, the WeedWise program may have resources available to assistance Clackamas County landowners to control or manage these weeds.  For more common invasive weeds, the WeedWise program offers technical information and consultations to improve your efforts and to make your management practices more effective.

WeedWise Classifications

Priority:  These weeds are the highest priority and are actively being targeted for eradication by the WeedWise Program.  Landowners are encouraged to notify the WeedWise program for assistance with these weeds and to actively control them on their property.

Maintenance:  These weeds are damaging and widespread.  The WeedWise Program encourages control by landowners and can assist with the development of a plan to control these weeds.

Containment:  These weeds are a priority for management, but in some areas, these weeds are so widespread that treatments of all infestations is not feasible.  For these weeds, infestations will be targeted for eradication when they occur outside of established containment areas.  Landowners are encouraged to contact the WeedWise program for assistance in controlling these weeds on properties that occur outside the containment areas, and for technical assistance in developing plans for management within containment areas.

Clackamas Weed List

Common NameScientific NameWeedWise ClassificationOregon ClassificationWashington Classification4-County CWMAColumbia Gorge CWMA
Barbed GoatgrassAegilops triuncialispriorityA,Tnot listedAW
Garlic mustardAlliaria petiolatapriorityB,TABA
Flowering rush Butomus umbellatuspriorityA,TAWA
Welted thistleWelted thistlepriorityA,Tnot listednot listednot listed
Rush skeletonweedChondrilla junceapriorityB, TBDB
HoundstongueCynoglossum officinalepriorityBBDB
Spurge laurelDaphne laureolapriorityBBBB
Oblong spurgeEuphorbia oblongatapriorityA,TAAA
GoatsrueGalega officinalispriorityA, TAAA
Giant hogweedHeracleum mantegazzianumpriorityA, TAAA
Orange hawkweedHieracium aurantiacumpriorityA,TBAA
Meadow hawkweedHieracium caespitosumpriorityB,TBAB
African ruePeganum harmalapriorityA,Tnot listedAW
Sulphur cinquefoilPotentilla rectapriorityBBAB
KudzuPueraria montanapriorityA,TAAA
Blessed milk thistleSilybum marianumpriorityBAAA
GorseUlex europaeuspriorityB,TBAA
Garden yellow loosestrifeLysimachia vulgarispriorityA,TBAW
Spiny cockleburXanthium spinosumpriorityBCDC
Syrian bean-caperZygophyllum fabagopriorityAAAA
Russian KnapweedAcroptilon repenspriorityBBAB
Pheasant eyeAdonis aestivalispriorityBnot listednot listednot listed
Jointed goatgrassAegilops cylindricapriorityBCnot listedC
Ovate GoatgrassAegilops ovatapriorityAnot listedAW
CamelthornAlhagi pseudalhagipriorityABAA
Yellow tuftAlyssum corsicumpriorityA,Tnot listedAW
Yellow tuftAlyssum muralepriorityA,Tnot listedAW
RagweedAmbrosia artemisiifoliapriorityBnot listedDB
Common buglossAnchusa officinalispriorityB,TBAB
Giant reedArundo donaxpriorityWnot listednot listedA
Hoary allysumBertoa incanapriorityA,TBAB
White bryoniaBryonia albapriorityABAA
Plumeless thistleCarduus acanthoidespriorityA,TBAA
Musk thistleCarduus nutanspriorityBBEB
Italian thistleCarduus pycnocephaluspriorityBADA
Slender-flowered thistleCarduus tenuifloruspriorityBADA
Smooth distaff thistleCarthamus baeticuspriorityAnot listedAW
Woolly distaff thistleCarthamus lanatuspriorityA,Tnot listedAW
Purple starthistleCentaurea calcitrapapriorityA,TAAA
Iberian starthistleCentaurea ibericapriorityA,Tnot listedAA
Yellow starthistleCentaurea solstitialispriorityBBAB
Squarrose knapweedCentaurea virgatapriorityA,Tnot listednot listedA
Jubata grassCortaderia jubatapriorityBCWB
Japanese dodder Cuscuta japonicapriorityAnot listedAW
Purple nutsedgeCyperus rotunduspriorityAnot listedAA
Cape ivyDelairea odoratapriorityAnot listedAW
Cutleaf teaselDipsacus laciniatuspriorityBnot listednot listedW
Paterson's curseEchium plantagineumpriorityA,Tnot listedAW
Leafy spurgeEuphorbia esulapriorityB, TBBA
HalogetonHalogeton glomeratuspriorityBnot listednot listedW
SpikeweedHemizonia pungenspriorityBCnot listedC
Yellow hawkweedHieracium × floribundumpriorityA,TBAA
Mouse-ear hawkweedHieracium pilosellapriorityA,TBAA
King-devil hawkweedHieracium piloselloidespriorityA,TBAA
HydrillaHydrilla verticillatapriorityAAWA
Common frogbitHydrocharis morsus-ranaepriorityAnot listedAW
Small-flowered jewelweedImpatiens parvifloraprioritynot listedAAA
KochiaKochia scopariapriorityBBnot listedB
Lens-podded whitetopLepidium chalepensispriorityBnot listedAB
Hoary cressLepidium drabapriorityBCAB
Perennial pepperweedLepidium latifoliumpriorityB,TBAB
Hairy whitetopLepidium pubescenspriorityBCnot listedC
West Indian spongeplantLimnobium laevigatumpriorityAAAW
MatgrassNardus strictapriorityA,Tnot listedAW
Yellow floating heartNymphoides peltatapriorityA, TBAA
Scotch thistleOnopordum acanthiumpriorityBBAB
Taurian thistleOnopordum tauricumpriorityA,Tnot listedAW
Common reed Phragmites australis ssp. australispriorityBBAB
Himalayan knotweedPolygonum polystachyumpriorityBBnot listedB
RavennagrassSaccharum ravennaepriorityAAAA
Silverleaf nightshadeSolanum elaeagnifoliumpriorityAAAA
BuffaloburSolanum rostratumpriorityBCDC
JohnsongrassSorghum halepensepriorityBAEA
Smooth cordgrassSpartina alterniflorapriorityA, TAAW
Common cordgrassSpartina anglicapriorityA,TAAW
Dense-flowered cordgrassSpartina densiflorapriorityA,TAAW
Saltmeadow cordgrassSpartina patenspriorityA,TAAW
Spanish broomSpartium junceumpriorityBAFA
Water soldiersStratiotes aloidespriorityAnot listedAnot listed
Medusahead ryeTaeniatherum caput-medusaepriorityBnot listedCC
European water chestnutTrapa natanspriorityAnot listedAA
PuncturevineTribulus terrestrispriorityBBCB
ColtsfootTussilago farfarapriorityABAA
VelvetleafAbutilon theophrastipriorityBBBB
False indigo bush Amorpha fruticosapriorityBBnot listedB
Biddy-biddyAcaena novae-zelandiaepriorityBnot listednot listedW
Portuguese broomCytisus striatuspriorityB,Tnot listedWW
French broomGenista monspessulanapriorityBAWA
Dyers woadIsatis tinctoriapriorityBAnot listedA
Dalmatian toadflaxLinaria dalmaticapriorityB, TBBB
Delta arrowheadSagittaria platyphyllapriorityAnot listedAnot listed
Ricefield bulrushSchoenoplectus mucronatuspriorityWADA
SwainsonpeaSphaerophysa salsulapriorityBCnot listedC
SaltcedarTamarix ramosissimapriorityB,TBWB
Eurasian watermilfoilMyriophyllum spicatummaintenanceBBCB
Tree of HeavenAilanthus altissimamaintenanceBCBC
Wild chervilAnthriscus sylvestrismaintenancenot listedBnot listedB
Italian arumArum italicummaintenancenot listedCBB
Butterfly bushBuddleja davidii (Buddleja varabilis)maintenanceBBBB
Meadow knapweedCentaurea × moncktonii (C. pratensis)maintenanceBBBB
Spotted knapweedCentaurea stoebe (C. maculosa)maintenanceB,TBBB
Canada thistleCirsium arvensemaintenanceBCCC
Bull thistleCirsium vulgaremaintenanceBCDC
Old man's beardClematis vitalbamaintenanceBCBC
Poison hemlockConium maculatummaintenanceBBBB
English hawthornCrataegus monogynamaintenanceWCCC
Yellow nutsedgeCyperus esculentusmaintenanceBBBB
Scotch broomCytisus scopariusmaintenanceBBCB
Wild carrot Daucus carotamaintenancenot listedCCC
Common teaselDipsacus fullonummaintenancenot listedCCC
South American waterweedEgeria densamaintenanceBBCB
Myrtle spurgeEuphorbia myrsinitesmaintenanceBBEB
Shining geraniumGeranium lucidummaintenanceBBBA
Herb robertGeranium robertianummaintenanceBBCB
English ivyHedera helixmaintenanceBCCB
Irish ivyHedera hibernicamaintenanceBCCB
St. John's wort Hypericum perforatummaintenanceBCCC
Hairy cat's earHypochaeris radicatamaintenancenot listedCCC
JewelweedImpatiens capensismaintenanceWCCW
Yellow archangelLamium galeobdolonmaintenanceBBBB
Small broomrapeOrobanche minormaintenanceBnot listedDA
RibbongrassPhalaris arundinacea var. pictamaintenanceB,T Cnot listedC
Reed canarygrassPhalaris arundinaceamaintenanceWCnot listedC
Curly-leaf pondweedPotamogeton crispusmaintenancenot listedCCC
Lesser celandineRanunculus ficariamaintenanceBBBB
Armenian (Himalayan) blackberryRubus armeniacus (R. bifrons, R. procerus, R. discolor)maintenanceBCCC
Evergreen blackberryRubus laciniatusmaintenancenot listedCCC
Tansy ragwortSenecio jacobaeamaintenanceBBBB
Common groundselSenecio vulgarismaintenancenot listedCnot listedC
Perennial sowthistleSonchus arvensis ssp. arvensismaintenancenot listedCDC
Common tansyTanacetum vulgaremaintenancenot listedCCC
Perennial peavineLathyrus latifoliusmaintenanceBnot listedCC
Oxeye daisyLeucanthemum vulgaremaintenancenot listedCCC
Yellow toadflaxLinaria vulgarismaintenanceBCBC
Parrots featherMyrophyllum aquaticummaintenanceBBBB
Yellow flag irisIris pseudacorusmaintenanceBCBB
Diffuse knapweedCentaurea diffusamaintenanceBBBB
Brown knapweedCentaurea jacea maintenancenot listedBFB
Big-headed knapweedCentaurea macrocephalamaintenanceWAnot listedA
Malta starthistleCentaurea melitensismaintenancenot listedBnot listednot listed
Black knapweedCentaurea nigra maintenancenot listedBnot listedB
Vochin knapweedCentaurea nigrescensmaintenancenot listedAnot listedA
Field bindweedConvolvulus arvensismaintenanceB,TCCC
Common crupinaCrupina vulgarismaintenanceBAnot listedW
Smoothseed alfalfa dodderCuscuta approximatamaintenanceBCnot listedC
Bigseed dodderCuscuta indecoramaintenanceBnot listednot listednotlisted
Five-angled dodderCuscuta pentagonamaintenanceBnot listednot listednotlisted
Spanish heath Erica lusitanicamaintenanceBnot listedWW
Creeping yellow cressRorippa sylvestrismaintenanceBnot listednot listedA
Mediterranean sageSalvia aethiopismaintenanceBAnot listedA
North Africa grassVentenata dubia ( V. avenacea )maintenanceBCnot listedC
Large-flowered primrose willowLudwigia grandifloracontainmentB, Tnot listednot listedB
Primrose willowLudwigia hexapetalacontainmentB, TBnot listedB
Water primroseLudwigia peploides ssp. montevidensiscontainmentB, TAAA
False bromeBrachypodium sylvaticumcontainmentBABA
Drooping sedgeCarex pendulacontainmentWnot listedWB
Policeman's helmet Impatiens glanduliferacontainmentBBBB
Purple loosestrifeLythrum salicaria containmentBBBB
Bohemian knotweedFallopia × bohemica ( Polygonum × bohemicum )containmentBBCB
Japanese knotweedFallopia japonica ( Polygonum cuspidatum )containmentBBBB
Giant knotweedFallopia sachalinensis ( Polygonum sachalinensis )containmentBBBB
Fragrant water lilyNymphaea odoratanot listedCDC
Japanese butterburPetasites japonicanot listednot listedWB
American pokeweedPhytolacca americanaWnot listedBA
BlackgrassAlopecurus myosuroidesnot listedCAW
Annual buglossAnchusa arvensisnot listedBnot listedB
Absinth wormwoodArtemisia absinthiumnot listedCnot listedC
South African capeweedArtotheca calendulaWnot listednot listedW
Common barberryBerberis vulgarisnot listedCnot listedW
FanwortCabomba caroliniananot listedBnot listedW
Whitestem distaff thistleCarthamus leucocaulosWnot listednot listedW
Wild safflowerCarthamus oxyacanthaWnot listednot listedW
Longspine sandburCenchrus longispinusnot listedCnot listedC
Feather-headed knapweedCentaurea trichocephalaWnot listednot listedW
Oriental clematisClematis orientalisnot listedAnot listedA
Pampass grassCortaderia selloananot listedCnot listedC
Tree echiumEchium pininanaWnot listednot listedW
Viper buglossEchium vulgareWBnot listedB
Water hyacinthEichhornia crassipesWnot listednot listednot listed
Russian oliveElaeagnus angustifolianot listedCnot listedC
Hairy willow-herbEpilobium hirsutum not listedBnot listedB
Toothed spurgeEuphorbia dentataWnot listednot listedW
Common fennelFoeniculum vulgarenot listedBCB
Reed sweetgrassGlyceria maximanot listedAnot listedA
BabysbreathGypsophila paniculatanot listedCnot listedC
Texas blueweedHelianthus ciliarisnot listedAnot listedA
Polar hawkweedHieracium atratumnot listedBnot listedW
Whiplash hawkweedHieracium flagellarenot listedBnot listedW
Queen-devil hawkweedHieracium glomeratumnot listedBnot listedW
Common hawkweedHieracium lachenaliinot listedBnot listedB
Pale hawkweedHieracium lactucellanot listedBnot listedW
Smooth hawkweedHieracium laevigatumnot listedBnot listedW
Spotted hawkweedHieracium maculatumnot listedBnot listedW
Wall hawkweedHieracium murorumnot listedBWW
European hawkweedHieracium sabaudumnot listedBnot listedW
Black henbaneHyoscyamus nigernot listedCnot listedC
LepyrodiclisLepyrodiclis holosteoidesnot listedCnot listedW
Rose campionLychnus coronariaWnot listednot listedW
Wand loosestrifeLythrum virgatum not listedBnot listedW
Scentless mayweedMatricaria perforatanot listedCnot listedC
Wild four o'clockMirabilis nyctagineanot listedAnot listedW
Variable-leaf milfoilMyriophyllum heterophyllumnot listedAnot listedA
Hybrid watermilfoil Myriophyllum spicatum × M. sibiricum not listedCnot listednot listed
Mile-a-minute weedPersicaria perfoliataWnot listednot listedW
Hawkweed oxtonguePicris hieracioides not listedBnot listedB
Austrian fieldcressRorippa austriacanot listedCnot listedC
Sweet briar roseRosa rubiginosa ( R.eglanteria )Wnot listednot listedW
Grass-leaved arrowheadSagittaria graminea not listedBnot listedW
Meadow clarySalvia pratensisnot listedAnot listedW
Clary sageSalvia sclareaWAnot listedW
Cereal ryeSecale cerealenot listedCnot listedC
White cockleSilene latifolia ssp. albanot listedCnot listedC
Sticky nightshadeSolanum sisymbriifoliumWnot listednot listedW
Field BurrweedSoliva sessilisnot listedCnot listedW
Spurge flaxThymelaea passerinanot listedBnot listedW
Narrowleaf cattailTypha angustifolianot listedCnot listedC
Southern cattailTypha domingensisnot listedCnot listedW
Miniature cattailTypha minimanot listedCnot listedW
White cattailTypha x glaucanot listedCnot listedW
Japanese eelgrassZostera japonicaWCnot listedW


The WeedWise Program is dedicated to helping protect Clackamas County from the ongoing threat of invasive weeds.  These projects are often based around the prevention or management or priority invasive weeds. We currently working on projects across the county, but focus largely on priority invasive weeds, priority sites, or on partnership projects.

Priority Weed Control Projects

Orange hawkweed control is an example of a priority weed control project underway at several locations in Clackamas County.

The priority weed control program focuses on the Early Detection and Rapid Response (EDRR) of new or rare invasive weeds where the goal is either eradication or containment.  These projects allow us to focus our resources for maximum impact.  Priority weed control projects typically occur at the landscape level and impact multiple landowners either public or private.  These project focus on the control and eradication of a priority weed species.  Some examples of our current priority weed control projects include the active management of:

  • Garlic mustard (Alliaria petiolata)
  • False brome (Brachypodium sylvaticum)
  • Spurge laurel (Daphne laureola)
  • Oblong spurge (Euphorbia oblongata)
  • Japanese, Giant, and Bohemian knotweed (Fallopia japonica, F. sachalinensis, and F. x bohemica)
  • Goatsrue (Galega officinalis)
  • Orange hawkweed (Hieracium aurantiacum)
  • Giant hogweed (Heracleum mantegazzianum)
  • Policeman’s helmet (Impatiens glandulifera)
  • Blessed Milk Thistle (Silybum marianum)
  • Puncturevine (Tribulus terrestris)
  • Gorse (Ulex europaeus)

The priority weed control projects are one of our highest priorities and target all known infestations across the county or within a given management area.

Priority Site Projects

The Bull Run Gate Project was initiated to protect the city of Portland’s municipal watershed from encroaching birds dispersed invasive weeds

Priority site projects are projects that are designed to protect areas of exceptional quality or of unique ecological, economic, or cultural importance.   Some examples of projects that the WeedWise program is currently working on or have spearheaded in the past include:

  • Barton Area Priority weeds project
  • Bull Run Gate weed control project
  • Coral Creek weed control project
  • Molalla River confluence project
  • Newell Creek restoration project
  • Salmon River priority weed control project
  • South Creek-Abernethy project
  • Lolo Pass priority weed control project

The priority site project areas are typically local or regional significance and are designed to protect or buffer these areas from  the encroachment or spread of invasive weeds.  The goals of these projects is typically focused on exclusion and maintenance of natural areas within the project areas.

Partnership Projects

Knotweed control efforts undertaken in conjunction with the Clackamas River Invasive Species Partnership, focus area project.

Partnership project are those projects that are typically undertaken in conjunction with local and regional partners.  These projects are often complex and have diverse interests.  These projects involve working in cooperation with partner organizations to implement projects across broad geographic areas or across jurisdictional boundaries.  Examples of partnership projects include:

Learn More

To learn more about our projects please check the project drop downs in the navigation menu above, or contact us about information pertaining to a particular project mentioned.

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