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Invasive & Noxious Weeds

219 invasive and noxious weed species tracked for Western Washington — identification, regulatory status, ecology, and control methods.

Classifications follow the Washington State Noxious Weed Control Board. Class A and B-designate weeds carry legal control obligations in this region.

Showing 219 weeds

Absinth Wormwood

Artemisia absinthium

Class C perennial herb

Peganum harmala

Monitor List perennial herb

Lycopsis arvensis

Class B (Designate) annual herb

Australian Water Clover

Marsilea mutica

Monitor List aquatic emergent

Austrian Fieldcress

Rorippa austriaca

Class C perennial herb

Gypsophila paniculata

Class C perennial herb

Bachelor’s Button

Centaurea cyanus

Monitor List annual herb

Balkan Catchfly

Monitor List annual herb

Beach grass, American, European, and hybrid

Ammophila breviligulata, A. arenaria, A. breviligulata x A. arenaria

Class C perennial herb

Bighead Knapweed

Centaurea macrocephala

Class A perennial herb

Hyoscyamus niger

Class C annual herb

Centaurea nigra

Class B (Designate) perennial herb

Robinia pseudoacacia

Alopecurus myosuroides

Class C annual herb

Colutea arborescens

Monitor List shrub

Adonis aestivalis

Monitor List annual herb

Class B (Designate) perennial herb

Bohemian Knotweed

Polygonum x bohemicum

Class B (Designate) perennial herb

Saponaria officinalis

Monitor List perennial herb

Brazilian Elodea

Class B (Designate) aquatic submersed

Centaurea jacea

Class B (Designate) perennial herb

Solanum rostratum

Class C annual herb

Cirsium vulgare

Class C biennial herb

Buddleja davidii

Class B (Designate) shrub

California sea lavender

Limonium californicum

Monitor List perennial herb

Alhagi maurorum

Class B (Designate) shrub

Aponogeton distachyos

Monitor List aquatic emergent

Class C annual herb

Prunus laurocerasus

Monitor List shrub

Class A perennial herb

Imperata cylindrica

Monitor List perennial herb

Common Barberry

Berberis vulgaris

Anchusa officinalis

Class B (Designate) perennial herb

Hypochaeris radicata

Class C perennial herb

Common Cordgrass

Spartina anglica

Class A perennial herb

Crupina vulgaris

Class A annual herb

Foeniculum vulgare

Class B (Designate) perennial herb

Common Groundsel

Senecio vulgaris

Class C annual herb

Common Hawthorn

Crataegus monogyna

Ilex aquifolium

Phragmites australis

Class B (Designate) perennial herb

Common St. Johnswort

Hypericum perforatum

Class C perennial herb

Tanacetum vulgare

Class B (Designate) perennial herb

Dipsacus fullonum

Class C perennial herb

Salix x rubens, Salix alba, Salix fragilis

Monitor List tree

Creeping bellflower

Campanula rapunculoides

Monitor List annual herb

Creeping Fieldcress

Rorippa sylvestris

Monitor List perennial herb

Lysimachia nummularia

Monitor List perennial herb

Creeping Thistle

Cirsium arvense

Class C perennial herb

Curlyleaf Pondweed

Potamogeton crispus

Class C perennial herb

Dalmatian Toadflax

Linaria dalmatica ssp. dalmatica

Class B (Designate) perennial herb

Delta arrowhead

Sagittaria platyphylla

Class A aquatic emergent

Dense-Flowered Cordgrass

Spartina densiflora

Class A perennial herb

Diffuse Knapweed

Centaurea diffusa

Class B (Designate) annual herb

Disk water hyssop

Bacopa rotundifolia

Monitor List perennial herb

Dyer’s Greenwood

Genista tinctoria

Monitor List shrub

Isatis tinctoria

Class A annual herb

Euphorbia oblongata

Class A perennial herb

Paulownia tomentosa

Monitor List tree

Hedera helix 'Baltica', 'Pittsburgh', and 'Star'; Hedera hibernica 'Hibernica

Eurasian Frogs-Bit

Hydrocharis morsus-ranae

Monitor List aquatic emergent

Eurasian Watermilfoil

Myriophyllum spicatum

Class B (Designate) aquatic submersed

Eurasian watermilfoil hybrid

Myriophyllum spicatum x Myriophyllum sibiricum

Class C aquatic submersed

European Coltsfoot

Tussilago farfara

Class B (Designate) perennial herb

Evergreen Blackberry

Rubus laciniatus

Brachypodium sylvaticum

Class A perennial herb

Cabomba caroliniana

Class B (Designate) aquatic submersed

February Daphne

Daphne mezereum

Monitor List shrub

Convolvulus arvensis

Floating Primrose-Willow

Ludwigia peploides

Class A aquatic emergent

Butomus umbellatus

Class A aquatic emergent

Fragrant Waterlily

Nymphaea odorata

Class C aquatic emergent

Genista monspessulana

Petasites japonicus

Monitor List perennial herb

Garden Helleborine

Epipactis helleborine

Monitor List perennial herb

Garden Loosestrife

Lysimachia vulgaris

Class B (Designate) perennial herb

Alliaria petiolata

Class A perennial herb

Heracleum mantegazzianum

Class A perennial herb

Polygonum sachalinense

Class B (Designate) perennial herb

Monitor List perennial herb

Galega officinalis

Class A perennial herb

Class B (Designate) shrub

Aegopodium podagraria

Monitor List perennial herb

Grass-Leaved Arrowhead

Sagittaria graminea

Class B (Designate) aquatic submersed

Monitor List perennial herb

Pentaglottis sempervirens

Class C perennial herb

Lepidium appelianum

Class C perennial herb

Hairy Willow-Herb

Epilobium hirsutum

Class B (Designate) aquatic emergent

Class B (Designate) perennial herb

Hawkweed Oxtongue

Picris hieracioides

Class B (Designate) annual herb

Geranium robertianum

Class B (Designate) annual herb

Himalayan Blackberry

Rubus armeniacus

Himalayan Knotweed

Persicaria wallichii

Class B (Designate) perennial herb

Berteroa incana

Class B (Designate) annual herb

Class C perennial herb

Cynoglossum officinale

Class B (Designate) perennial herb

Hydrilla verticillata

Class A aquatic submersed

Amorpha fruticosa

Class B (Designate) shrub

Class C perennial herb

Italian Thistle

Carduus pycnocephalus

Class A annual herb

Japanese Eelgrass

Nanozostera japonica

Class C aquatic emergent

Japanese Knotweed

Polygonum cuspidatum

Class B (Designate) shrub

Sorghum halepense

Class A perennial herb

Jointed Goatgrass

Aegilops cylindrica

Class C annual herb

Cortaderia jubata

Class C perennial herb

Bassia scoparia

Class B (Designate) annual herb

Pueraria montana var. lobata

Soliva sessilis

Class C annual herb

Euphorbia virgata

Class B (Designate) perennial herb

Doronicum sp., Doronicum x willdenowii

Monitor List perennial herb

Lepyrodiclis holosteoides

Class C annual herb

Lesser Celandine

Class B (Designate) perennial herb

Longspine Sandbur

Cenchrus longispinus

Class C annual herb

Monitor List tree

Miscanthus sinensis

Monitor List perennial herb

Malta starthistle

Centaurea melitensis

Class B (Designate) annual herb

Cirsium palustre

Class A perennial herb

Salvia pratensis

Class A perennial herb

Meadow Knapweed

Centaurea x moncktonii

Class B (Designate) perennial herb

Mediterranean Sage

Salvia aethiopis

Class A perennial herb

Taeniatherum caput-medusae

Class C annual herb

Silybum marianum

Class A perennial herb

Euphorbia lathyris

Monitor List perennial herb

Sorbus aucuparia

Monitor List tree

Multiflora Rose

Rosa multiflora

Monitor List shrub

Class B (Designate) annual herb

Euphorbia myrsinites

Class B (Designate) perennial herb

Nonnative Cattails

Class C perennial herb

Nonnative Hawkweed Species & Hybrids of Meadow Subgenus

Hieracium subgenus Pilosella

Class B (Designate) perennial herb

Nonnative Hawkweed Species & Hybrids of Wall Subgenus

Hieracium subgenus Hieracium

Class B (Designate) perennial herb

Acer platanoides

Old Man's Beard

Clematis vitalba

Orange Hawkweed

Hieracium aurantiacum

Class B (Designate) perennial herb

Oriental Clematis

Clematis orientalis

Leucanthemum vulgare

Class C perennial herb

Palmer Amaranth

Amaranthus palmeri

Class A annual herb

Cortaderia selloana

Class C perennial herb

Myriophyllum aquaticum

Class B (Designate) aquatic submersed

Perennial Cornflower

Centaurea montana

Monitor List perennial herb

Perennial Peavine

Lathyrus latifolius

Monitor List vine

Perennial Pepperweed

Lepidium latifolium

Class B (Designate) perennial herb

Perennial Sowthistle

Sonchus arvensis ssp. arvensis

Class C perennial herb

Periwinkle, large and small

Vinca minor, Vinca major

Monitor List perennial herb

Plumeless Thistle

Carduus acanthoides

Class B (Designate) biennial herb

Conium maculatum

Class B (Designate) biennial herb

Phytolacca americana

Monitor List perennial herb

Policeman's Helmet

Impatiens glandulifera

Class B (Designate) annual herb

Privet, Common and California Privets

Ligustrum vulgare, Lingustrum ovalifolium

Monitor List shrub

Tribulus terrestris

Class B (Designate) vine

Purple Loosestrife

Lythrum salicaria

Class B (Designate) aquatic emergent

Purple Starthistle

Centaurea calcitrapa

Class A annual herb

Tripidium ravennae

Class B (Designate) perennial herb

Reed Canarygrass

Phalaris arundinacea

Class C perennial herb

Reed Sweetgrass

Glyceria maxima

Class A perennial herb

Ricefield Bulrush

Schoenoplectus mucronatus

Class A aquatic emergent

Chaerophyllum temulum

Class B (Designate) biennial herb

Round Leaf Bittersweet

Celastrus orbiculatus

Rush Skeletonweed

Chondrilla juncea

Class B (Designate) perennial herb

Russian Knapweed

Rhaponticum repens

Class B (Designate) perennial herb

Elaeagnus angustifolia

Salt Meadow Cordgrass

Spartina patens

Class A perennial herb

Tamarix ramosissima

Class B (Designate) tree

Scentless Mayweed

Matricaria perforata

Class C annual herb

Cytisus scoparius

Class B (Designate) shrub

Onopordum acanthium

Class B (Designate) annual herb

Sessile-fruited arrowhead

Sagittaria rigida

Monitor List aquatic emergent

Geranium lucidum

Class B (Designate) annual herb

Silverlace Vine

Polygonum aubertii

Monitor List vine

Silverleaf Nightshade

Solanum elaeagnifolium

Class A perennial herb

Silvery Cinquefoil

Potentilla argentea

Monitor List perennial herb

Slenderflower Thistle

Carduus tenuiflorus

Class A perennial herb

Small-flowered Jewelweed

Impatiens parviflora

Class A annual herb

Smooth Cordgrass

Spartina alterniflora

Class A perennial herb

Smoothseed Alfalfa Dodder

Cuscuta approximata

Class C annual herb

South American spongeplant

Limnobium laevigatum

Class A aquatic emergent

Spartium junceum

Centromadia pungens

Class C annual herb

Spiny Cocklebur

Xanthium spinosum

Class C annual herb

Spotted Jewelweed

Impatiens capensis

Class C annual herb

Spotted Knapweed

Centaurea stoebe

Class B (Designate) perennial herb

Thymelaea passerina

Class B (Designate) annual herb

Daphne laureola

Class B (Designate) shrub

Iris foetidissima

Monitor List perennial herb

Sulfur Cinquefoil

Potentilla recta

Class B (Designate) perennial herb

Sunflower broomrape

Orobanche cumana

Sphaerophysa salsula

Class C perennial herb

Sweetbriar rose

Rosa rubiginosa

Monitor List shrub

Swollen Bladderwort

Utricularia inflata

Monitor List aquatic emergent

Syrian Bean-Caper

Zygophyllum fabago

Cyperus eragrostis

Monitor List perennial herb

Verbena bonariensis

Monitor List perennial herb

Jacobaea vulgaris

Class B (Designate) annual herb

Helianthus ciliaris

Class A perennial herb

Ailanthus altissima

Turkish thistle

Carduus cinereus

Class A annual herb

Variable-Leaf Milfoil, and Hybrid variable-leaf milfoil

Myriophyllum heterophyllum, Myriophyllum heterophyllum x Myriophyllum hippuroides

Class A aquatic submersed

Abutilon theophrasti

Class B (Designate) annual herb

Ventenata dubia

Class C annual herb

Virginia Creeper

Parthenocissus vitacea

Monitor List tree

Vochin Knapweed

Centaurea nigrescens

Class A perennial herb

Wand Loosestrife

Lythrum virgatum

Class B (Designate) perennial herb

Eichhornia crassipes

Monitor List aquatic emergent

Ludwigia hexapetala

Class B (Designate) aquatic emergent

Ipomoea aquatica

Monitor List vine

Amaranthus tuberculatus

Class A annual herb

Class B (Designate) vine

Silene latifolia ssp. alba

Class C perennial herb

Clinopodium vulgare

Class B (Designate) perennial herb

Class C annual herb

Anthriscus sylvestris

Class B (Designate) perennial herb

Wild Four O'Clock

Mirabilis nyctaginea

Class A perennial herb

Tulipa sylvestris

Monitor List perennial herb

Woolly Distaff Thistle

Carthamus lanatus

Monitor List annual herb

Yellow Archangel

Lamiastrum galeobdolon

Class B (Designate) perennial herb

Yellow Flag Iris

Iris pseudacorus

Class C aquatic emergent

Yellow Floating Heart

Nymphoides peltata

Class B (Designate) aquatic emergent

Yellow Nutsedge

Cyperus esculentus

Class B (Designate) perennial herb

Yellow Starthistle

Centaurea solstitialis

Class B (Designate) annual herb

Yellow Toadflax

Linaria vulgaris

Class C perennial herb

WA Noxious Weed Classifications

Class A: Statewide eradication required. Landowners must eliminate all plants.
Class B (Designate): Required control in your NWCB region. All of western WA is Region 1.
Class B (Non-designate): Listed statewide but not designated for required control in this region.
Class C: Selected by individual counties for local control requirements.
Monitor List: Tracked for potential future listing. No control requirement.

Source: Washington State Noxious Weed Control Board