Class C Weeds

Each species is already widely established in Washington or is of special interest to the state’s agricultural industry. Placement on the state noxious weed list allows counties to enforce control if locally desired. Other counties may choose simply to provide education or technical consultation to county residents.

Canada thistle, a Class C noxious weed, illustrated the desirability of a law that provides local flexibility. This species is widely established in Washington, and most counties prefer to provide technical consultation to landowners on methods of suppression and control. Enforcement of control is the preferred policy, however, in those counties which have crops grown for certified seed. 

Washington State Noxious Weed List - Class C Weeds

Common NameScientific Name
babysbreathGypsophila paniculata
bindweed, fieldConvolvulus arvensis
Butterfly BushBuddleia davidii
canarygrass, reedPhalaris arundinacea
cockle, whiteSilene latifolia ssp. alba
cocklebur, spinyXanthium spinosum
Common Reed (non native genotypes)Phragmites australis
cress, hoaryCardaria draba
Curly-leaf pondweedPotamogeton crispus
dodder,Cuscuta approximata
goatgrass, jointedAegilops cylindrica
Groundsel, commonSenecio vulgaris
hawkweed, spp*Non-Native hieracium
henbane, blackHyoscyamus niger
iris, yellow flagIris pseudocorus
ivy, English*4 Cultivars only
  • Hedera helix ’Star’
  • Hedera helix ’Baltica’
  • Hedera helix ’Pittsburgh’
  • Hedera hibernica ’Hibernica’
Knotweed bohemianPolygonum Bohemicum
Mayweed, scentlessMatricaria perforata
old man’s beardClematis vitalba
poison-hemlockConium maculatum
rye, cerealSecale cereale
spikeweedHemizonia pungens
St. Johnswort, commonHypericum perforatum
tansy, commonTanacetum vulgare
thistle, bullCirsium vulgare
thistle, CanadaCirsium arvense
toadflax, YellowLinaria vulgaris
Willowherb, hairyEpilobium hirsutum
wormwood, absinthArtemisia absinthium