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Washington State Noxious Weed List

Class B Weeds

These species are established in some regions of Washington, but are of limited distribution or not present in other regions of the state. Because of differences in distribution, treatment of Class B weeds varies between regions of the state. In regions where a Class B is unrecorded or of limited distribution, prevention of seed production is required. In these areas, the weed is a "Class B designate," meaning it is designated for control by state law. In regions where a Class B species is already abundant or widespread, control is a local option. In these areas the weed is a "Class B non-designate," with containment, gradual reduction, and prevention of further spread being the chief goals

Scientific Name:

Common Name:

 Washington State Noxious Weed List - Class B Weeds

Common Name

Scientific Name

Common Name

Scientific Name

Annual bugloss

Anchusa arvensis

Musk thistle

Carduus nutans

Austrian fieldcress

Rorippa austriaca

Myrtle spurge

Euphorbia myrsinites

Black knapweed

Centaurea nigra

Orange hawkweed

Hieracium aurantiacum


Alopecurus myosuroides

Oxeye daisy

Leucanthemum vulgare


Echium vulgare

Oxtongue hawkweed

Picris hieracioides

Bohemian knotweed

Polygonum bohemicum


Myriophyllum aquaticum

Brazilian elodea

Egeria densa

Perennial pepperweed

Lepidium latifolium

Brown knapweed

Centaurea jacea

Perennial sowthistle

Sonchus arvensis


Alhagi maurorum

Plumeless thistle

Carduus acanthoides

Common bugloss

Anchusa officinalis

Polar hawkweed

Hieracium atratum

Common catsear

Hypochaeris radicata

Policeman's helmet

Impatiens glandulifera

Common cordgrass

Spartina anglica


Tribulus terrestris

Dalmatian toadflax

Linaria dalmatica ssp. Dalmatica

Purple loosestrife

Lythrum salicaria

Diffuse knapweed

Centaurea diffusa

Queendevil hawkweed

Hieracium glomeratum

Eurasian watermilfoil

Myriophyllum spicatum

Rush skeletonweed

Chondrilla juncea


Cabomba caroliniana

Russian knapweed

Acroptilon repens

Garden loosestrife

Lysimachia vulgaris


Tamarix ramosissima

Giant knotweed

Polygonum sachalinense

Scotch broom

Cytisus scoparius


Ulex europaeus

Scotch thistle

Onopordum acanthium

Grass-leaved arrowhead

Sagittaria graminea

Smooth cordgrass

Spartina alterniflora


Torilis arvensis

Smooth hawkweed

Hieracium laevigatum


Geranium robertianum

Spotted knapweed

Centaurea biebersteinii

Himalayan knotweed

Polygonum polystachyum

Sulfur cinquefoil

Potentilla recta

Hoary alyssum

Berteroa incana


Sphaerophysa salsula


Cynoglossum officinale

Tansy ragwort

Senecio jacobaea


Amorpha fruticosa

Wand loosestrife

Lythrum virgatum

Japanese knotweed

Polygonum cuspidatum

Water primrose

Ludwigia hexapetala


Kochia scoparia

White bryony

Bryonia alba

Leafy spurge

Euphorbia esula

Wild carrot

Daucus carota


Lepyrodiclis holosteoides

Wild chervil

Anthriscus sylvestris

Longspine sandbur

Cenchrus longispinus

Yellow floating heart

Nymphoides peltata

Meadow knapweed

Centaurea pratensis

Yellow hawkweed

Hieracium caespitosum

Mouseear hawkweed

Hieracium pilosella



Pictures for many of these weeds may be found at Washington State Noxious Weed Board's website.

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