King County Noxious Weed List
By scientific name
- Class A Noxious Weeds
- Class B Noxious Weeds
- Class C Noxious Weeds
- Non-Regulated Noxious Weeds
- Weeds of Concern List
Regulated Class A noxious weeds
(eradication required throughout Washington State including King County)
| Scientific name | Common name | State class |
|---|---|---|
| Alliaria petiolata | garlic mustard | A |
| Brachypodium sylvaticum | false brome | A |
| Butomus umbellatus | flowering-rush | A |
| Carduus cinereus (external link)9l | ashen thistle | A |
| Carduus pycnocephalus (external link)9m | shore thistle | A |
| Carduus tenuiflorus | slenderflower thistle | A |
| Centaurea calcitrapa | purple starthistle | A |
| Centaurea macrocephala | bighead knapweed | A |
| Centaurea nigrescens9h | short fringed knapweed | A |
| Clematis orientalis9i | orange peel clematis | A |
| Crufpina vulgaris | common crupina | A |
| Euphorbia oblongata (external link) | eggleaf spurge | A |
| Galega officinalis | goatsrue | A |
| Genista monspessulana | French broom | A |
| Glyceria maxima | reed sweetgrass | A |
| Helanthus ciliarus | Texas blueweed | A |
| Heracleum mantegazzianum | giant hogweed | A |
| Hydrilla verticillata | hydrilla | A |
| Impatiens parviflora | small-flowered jewelweed | A |
| Isatis tinctoria | dyers woad | A |
| Limnobium laevigatum (external link)9k | smooth frogbit | A |
| Ludwigia peploides | floating primrose-willow | A |
| Mirabilis nyctaginea (external link) | wild four o'clock | A |
| Myriophyllum heterophyllum | variable-leaf milfoil | A |
| Pueraria montana var. lobata | kudzu | A |
| Salvia pratensis | meadow clary | A |
| Salvia sclarea | clary sage | A |
| Salvia aethiopis | Mediterranean sage | A |
| Schoenoplectus mucronatus (external link) | ricefield bulrush | A |
| Silybum marianum | milk thistle | A |
| Solanum elaeagnifolium (external link) | silverleaf nightshade | A |
| Sorghum halepense (external link) | Johnsongrass | A |
| Spartina alterniflora | smooth cordgrass | A |
| Spartina anglica | common cordgrass | A |
| Spartina densiflora (external link) | dense flower cordgrass | A |
| Spartina patens | salt meadow cordgrass | A |
| Spartium junceum9j | rush broom | A |
| Zygophyllum fabago9g | bean-caper | A |
Regulated Class B noxious weeds
(control is required for these species in King County)
| Scientific name | Common name | State class |
|---|---|---|
| Abutilon theophrasti | velvetleaf | B |
| Alhagi maurorum (external link) | camelthorn | B |
| Amorpha fruticosa (external link) | indigobush | B |
| Anchusa officinalis | common bugloss | B |
| Anthriscus sylvestris |
wild chervil | B |
| Bassia scoparia |
kochia | B |
| Berteroa incana (external link) | hoary alyssum | B |
| Bryonia alba (external link) | white bryony | B |
| Cabomba caroliniana | fanwort | B |
| Carduus nutans | musk thistle | B |
| Carduus acanthoides (external link) |
plumeless thistle | B |
| Centaurea melitensis (external link) 9n | Malta starthistle | B |
| Centaurea solstitialis | yellow starthistle | B |
| Centaurea biebersteinii | spotted knapweed | B |
| Centaurea nigra | black knapweed | B |
| Centaurea jacea | brown knapweed | B |
| Centaurea diffusa | diffuse knapweed | B |
| Centaurea x gerstlaueri | meadow knapweed | B |
| Chondrilla juncea | rush skeletonweed | B |
| Clinopodium vulgare8a | wild basil | B |
| Cynoglossum officinale | houndstongue | B |
| Cyperus esculentus | yellow nutsedge | B |
| Echium vulgare | blueweed, viper's bugloss | B |
| Egeria densa1, 9a | Egeria; Brazilian elodea | B |
| Epilobium hirsutum | hairy willowherb | B |
| Euphorbia virgata | leafy spurge | B |
| Geranium lucidum | shiny geranium | B |
| Hieracium, subgenus Pilosella2 | hawkweeds: all non-native species and hybrids of the meadow subgenus | B |
| Hieracium aurantiacum | orange hawkweed | B |
| Hieracium sabaudum | European hawkweed | B |
| Impatiens glandulifera | policeman's helmet | B |
| Jacobaea vulgaris3 |
tansy ragwort | B |
| Lepidium latifolium | perennial pepperweed | B |
| Linaria dalmatica ssp. dalmatica | Dalmatian toadflax | B |
| Ludwigia hexapetala | water primrose | B |
| Lycopus arvensis |
annual bugloss | B |
| Lysimachia vulgaris | garden loosestrife | B |
| Lythrum salicaria | purple loosestrife | B |
| Myriophyllum aquaticum | parrotfeather | B |
| Nymphoides peltata | yellow floating heart | B |
| Onopordum acanthium | Scotch thistle | B |
| Phragmites australis | common reed (non-native genotypes) | B |
| Picris hieracioides (external link) | hawkweed oxtongue | B |
| Potentilla recta | sulfur cinquefoil | B |
| Rhaponticum repens |
Russian knapweed | B |
| Sagittaria graminea (external link) | grass-leaved arrowhead | B |
| Tamarix ramosissima | saltcedar | B |
| Tussilago farfara | European coltsfoot | B |
| Ulex europaeus | gorse | B |
| 1. Egeria is designated for control throughout King County except in Lake Washington, Lake Sammamish, Lake Union, Lake Fenwick, Lake Doloff and the Sammamish River. | ||
| 2. Non-native yellow-flowered hawkweeds (Hieracium species): the 11 separate listings of yellow-flowered hawkweeds that were previously on the noxious weed list are now consolidated into two Class B listings by subgenus - meadow (Pilosella) and wall (Hieracium). In general, the meadow subgenus species have stolons present, have no or few leaves on the stems, and have leaf edges that are smooth or minutely toothed. The wall subgenus species in contrast generally lack stolons, have stem leaves, and have leaf edges that are conspicuously toothed or lobed. The wall subgenus species of hawkweed are not designated by the State Weed Board for control in King County. However, the species European hawkweed (Hieracium sabaudum) in the wall subgenus has been selected by the King County Weed Board for required control in all areas of King County. All species of the meadow subgenus are designated by the State Weed Board for required control in King County. | ||
| 3. Tansy ragwort is not designated by the State Weed Board for control in King County, but has been selected by the King County Weed Board for required control in all areas of King County. | ||
Regulated Class C noxious weeds
(control is required for these species in King County)
| Scientific name | Common name | State class |
|---|---|---|
| Artemisia absinthium | absinth wormwood | C |
| Solanum rostratum | buffalobur | C |
Non-regulated Class B and C noxious weeds
(Class B and C noxious weeds that are not designated for control in King County, control recommended but not required in King County. Species that are classified with "selective" require control within specific parameters. See notes for details.)
| Scientific name | Common name | State class |
|---|---|---|
| Ailanthus altissima (external link) | tree-of-heaven | C |
| Arum italicum (external link) | Italian arum | C |
| Berberis vulgaris (external link) | common barberry | C |
| Buddleia davidii | butterfly bush | B |
| Carex pendula (ssp. pendula and ssp. agastachys)5 |
hanging sedge | B (selective) |
| Chaerophyllum temulum5 | rough chervill | B (selective |
| Cirsium arvense9e | creeping thistle; Canada thistle | C |
| Cirsium vulgare | bull thistle | C |
| Clematis vitalba | old man's beard | C |
| Conium maculatum | poison-hemlock | B (selective) |
| Convolvulus arvensis | field bindweed | C |
| Cortaderia jubata (external link) | jubata grass | C |
| Cortaderia selloana (external link) | Pampas grass | C |
| Crataegus monogyna9b | common hawthorn; English hawthorn | C |
| Cytisus scoparius6 | Scotch broom | B (selective) |
| Daphne laureola | spurge laurel | B |
| Daucus carota | wild carrot | C |
| Dipsacus fullonum | common teasel | C |
| Fallopia x bohemica5, 9c | hybrid knotweed; Bohemian knotweed | B (selective) |
| Fallopia japonica5, 9d | itadori knotweed; Japanese knotweed | B (selective) |
| Fallopia sachalinensis5 | giant knotweed | B (selective) |
| Ficaria verna (external link) | lesser celandine | B |
| Foeniculum vulgare (excluding F. vulgare var. azoricum) (external link) | common fennel (except bulbing variety azoricum) | B |
| Geranium lucidum8b,10 | shiny geranium | B (selective) |
| Geranium robertianum | herb Robert | B |
| Hedera helix Baltica | English ivy | C |
| Hedera helix Pittsburgh | English ivy | C |
| Hedera helix Star | English ivy | C |
| Hedera hibernica | Atlantic ivy | C |
| Hieracium, subgenus Hieracium (except Hieracium sabaudum)2 | hawkweeds: all non-native species and hybrids of the wall subgenus | B |
| Hypericum perforatum4 | common St. Johnswort | C |
| Hypochaeris radicata (external link) | common catsear | C |
| Impatiens capensis (external link) | spotted jewelweed | C |
| Iris pseudacorus | yellow flag iris | C |
| Lamiastrum galeobdolon | yellow archangel | B |
| Lepidium draba (external link) | hoary cress | C |
| Lepidium appelianum (external link) | hairy whitetop | C |
| Leucanthemum vulgare | oxeye daisy | C |
| Linaria vulgaris | yellow toadflax | C |
| Myriophyllum spicatum | Eurasian watermilfoil | B |
| Myriophyllum spicatum x. M. sibiricum (external link) | Eurasian watermilfoil hybrid | C |
| Nymphaea odorata | fragrant water lily | C |
| Persicaria wallichii5 | Himalayan knotweed | B (selective) |
| Phalaris arundinacea | reed canarygrass | C |
| Potamogeton crispus (external link) | curly-leaf pondweed | C |
| Rubus bifrons or Rubus armeniacus | Himalayan blackberry | C |
| Rubus laciniatus |
evergreen blackberry | C |
| Senecio vulgaris (external link) | common groundsel | C |
| Silene latifolia (external link) | white cockle | C |
| Soliva sessilis | lawnweed | C |
| Sonchus arvensis ssp. arvensis | perennial sowthistle | C |
| Tanacetum vulgare | common tansy | C |
| Tripidium ravennae (external link) | Ravenna grass | B |
| Tripleurospermum inodorum (external link) | Scentless mayweed | B |
| Typha spp. including Typha angustifolia, T. domingensis, and T. x glauca (and any other nonnative Typha spp.) (does not include native species T. latifolia) (external link) | nonnative cattail species and hybrids (does not include native species common cattail) | C |
| Ventenata dubia (external link) | Ventenata | C |
| Xanthium spinosum (external link) | spiny cocklebur | C |
King County weeds of concern
(This list is for educational purposes only; these species are not classified as noxious weeds in Washington State. These species often impact and degrade native plant and animal habitat. Control is recommended where possible and new plantings are discouraged.)
| Scientific name | Common name | State class |
|---|---|---|
| Acer platanoides8a | harlequin maple; Norway maple | NONE |
| Aegopodium podagraria | bishop's weed | NONE |
| Aesculus hippocastanum | horse-chestnut | NONE |
| Carex pendula | hanging sedge | NONE |
| Chaerophyllum temulum |
rough chervil | NONE |
| Convolvulus sepium | hedge bindweed; morning glory | NONE |
| Fallopia baldschuanica (syn. Polygonum aubertii) |
silver lace vine | NONE |
| Ilex aquifolium8c | common holly; English holly | NONE |
| Lotus corniculatus | bird's-foot trefoil | NONE |
| Prunus avium | bird cherry | NONE |
| Prunus laurocerasus | cherry laurel; English laurel | NONE |
| Ranunculus acris | tall buttercup | NONE |
| Ranunculus repens | creeping buttercup | NONE |
| Robinia pseudoacacia | black locust | NONE |
| Lathyrus sylvestris, L. latifolius8a | introduced peavines | NONE |
| Rosa multiflora | multiflora rose | NONE |
| Solanum dulcamara | bittersweet nightshade | NONE |
| Sorbus aucuparia | European mountain-ash |
NONE |
|
NOTESBold font indicates a change for 2023 (see note 8)
1. Egeria is designated for control throughout King County except in Lake Washington, Lake Sammamish, Lake Union, Lake Fenwick, Lake Doloff and the Sammamish River.
2. Non-native yellow-flowered hawkweeds (Hieracium species) are consolidated into two Class B listings by subgenus - meadow (Pilosella) and wall (Hieracium). All species of the meadow subgenus are designated by the State Weed Board for required control in King County. The species European hawkweed (Hieracium sabaudum) in the wall hawkweed subgenus has been selected by the King County Weed Board for required control throughout King County. Control of all other species in the wall hawkweed subgenus is not required in King County.
3. Tansy ragwort is not designated by the State Weed Board for control in King County, but has been selected by the King County Weed Board for required control in all areas of King County.
4. Permit from KC Weed Board required to grow common St. Johnswort as a crop in King County.
5. Control of rough chervil; hanging sedge; hybrid, itadori, giant, and Himalayan knotweed is required on the Green River and its tributaries upstream of the Auburn City Limits and on the Cedar River and its tributaries upstream of the Renton City Limits (tributaries included are those defined as Type S, F or N aquatic areas in KCC 21A.24.355). Control of these invasive knotweed species is required up to the ordinary high water mark (or up to the top of the bank if the ordinary high water mark cannot be identified) and in the adjacent buffer area as specified in KCC 21A.24.358. This requirement to control knotweed is contingent upon the noxious weed program or program partners providing knotweed control services in the selected area for affected private landowners who request assistance.
6. Control of Scotch broom is required on the right-of-way of King County's section of SR-2 and on the I-90 right-of-way between mile marker 34 and the King/Kittitas county line.
7. Control of poison hemlock is required on all public lands and public rights-of-way within King County.
8. Change indicated from 2022 list:
a. Additions to list: harlequin or Norway maple; introduced peavines
b. Additions to rules: shiny geranium selection defined in note 10
c. Common names to be changed to uniquely descriptive name or away from nationalist and/or exclusionary language: common or English holly
9. Previous common name changes (within the last 3 years): a. Brazilian elodea; b. English hawthorn; c. Bohemian knotweed; d. Japanese knotweed; e. Canada thistle; f. English laurel; g. Syrian bean-caper; h. Vochin knapweed; i. Oriental clematis; j. Spanish broom; k. South American spongeplant; l. Turkish thistle; m. Italian thistle; n. Malta starthistle; o. Italian arum 10. Control of shiny geranium is required is required at any elevation equal to or greater than 1000 feet within King County.
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Related information
Related agencies
Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact staff, see the Noxious Weed Control Program Directory, send an email, or call 206-477-WEED (206-477-9333).