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King County noxious weeds list
The King County Noxious Weed Control Board has adopted this Noxious Weed List based on these state laws:
About the noxious weeds list
Find noxious weeds using the tables below. The tables organize weeds by class and lists entries alphabetically. There are tabs for scientific and common names. The superscript numbers refer to additional notes, which are listed at the bottom of each tab.
For the "In King County" column:
Yes: Known to occur in King County.
Historically: Historically present but thought to be eradicated.
No: Not present in King County.This tab displays noxious weeds listed alphabetically by their common names.
- Class A noxious weeds
- Class B noxious weeds
- Class C noxious weeds
- Non-Regulated noxious weeds
- Weeds of concern
- Notes
Regulated Class A weeds
State law requires property owners to eradicate all Class A species due to potential threat and limited distribution:
| In King County |
Common name |
Scientific name |
Class |
|---|---|---|---|
| No | bean-caper9g | Zygophyllum fabago | A |
| Yes | common crupina | Crupina vulgaris | A |
| Yes | cordgrass, common | Spartina anglica | A |
| No | cordgrass, dense flowered | Spartina densiflora | A |
| No | cordgrass, salt meadow | Spartina patens | A |
| No | cordgrass, smooth | Spartina alterniflora | A |
| No | dyers woad | Isatis tinctoria | A |
| Yes | eggleaf spurge | Euphorbia oblongata | A |
| Yes | false brome | Brachypodium sylvaticum | A |
| Yes | floating primrose-willow | Ludwigia peploides | A |
| No | flowering rush | Butomus umbellatus | A |
| Yes | garlic mustard | alliaria petiolata | A |
| Yes | giant hogweed | Heracleum mantegazzianum | A |
| Yes | goatsrue | Galega officinalis | A |
| Historically | hydrilla | Hydrilla verticillata | A |
| No | Johnsongrass | Sorghum halepense | A |
| Yes | knapweed, bighead | Centaurea macrocephala | A |
| No | kudzu | Pueraria montana var. lobata | A |
| No | meadow clary | Salvia pratensis | A |
| No | orange peel clematis9i | Clematis orientalis | A |
| No | purple starthistle | Centaurea calcitrapa | A |
| Yes | reed sweetgrass | Glyceria maxima | A |
| Yes | ricefield bulrush | Schoenoplectus mucronatus | A |
| Yes | rush broom9j | Spartium junceum | A |
| Historically | sage, clary | Salvia sclarea | A |
| No | sage, Mediterranean | Salvia aethiopis | A |
| No | silverleaf nightshade | Solanum elaeagnifolium | A |
| Yes | small-flowered jewelweed | Impatiens parviflora | A |
| Yes | smooth frogbit9k | Limnobium laevigatum | A |
| Yes | soft broom | Genista monspessulana | A |
| No | Texas blueweed | Helianthus ciliaris | A |
| No | thistle, ashen9l | Carduus cinereus | A |
| Yes | thistle, milk | Silybum marianum | A |
| No | thistle, shore9m | Carduus pycnocephalus | A |
| No | thistle, slenderflower | Carduus tenuiflorus | A |
| No | variable-leaf milfoil | Myriophyllum heterophyllum | A |
| No | wild four o'clock | Mirabilis nyctaginea | A |
Regulated Class B weeds
Regulated in counties where they are limited in distribution or a local priority. The following Class B weeds have been designated by the State Weed Board or selected by the King County Weed Board. Property owners in King County are required to control these species.
| In King County |
Common name |
Scientific name |
Class |
|---|---|---|---|
| Yes | blueweed; viper's bugloss | Echium vulgare | B-Regulated |
| Historically | bugloss, annual | Lycopsis arvensis | B-Regulated |
| Yes | bugloss, common | Anchusa officinalis | B-Regulated |
| Yes | camelthorn | Alhagi maurorum | B-Regulated |
| Yes | common reed (non-native genotypes) | Phragmites australis | B-Regulated |
| Yes | Dalmatian toadflax | Linaria dalmatica ssp. dalmatica | B-Regulated |
| Yes | Egeria1,9a | Egeria densa | B-Regulated |
| Yes | European coltsfoot | Tussilago farfara | B-Regulated |
| No | fanwort | Cabomba caroliniana | B-Regulated |
| Yes | gorse | Ulex europaeus | B-Regulated |
| No | grass-leaved arrowhead | Sagittaria graminea | B-Regulated |
| Yes | hairy willow-herb | Epilobium hirsutum | B-Regulated |
| Yes | hawkweeds: all non-native species and hybrids of the meadow subgenus2 Hieracium, subgenus | Pilosella | B-Regulated |
| Yes | hawkweed, European | Hieracium sabaudum | B-Regulated |
| Yes | hawkweed, orange | Hieracium aurantiacum | B-Regulated |
| No | hawkweed oxtongue | Picris hieracioides | B-Regulated |
| No | hoary alyssum | Berteroa incana | B-Regulated |
| Yes | houndstongue | Cynoglossum officinale | B-Regulated |
| No | indigobush | Amorpha fruticosa | B-Regulated |
| No | knapweed, black | Centaurea nigra | B-Regulated |
| Historically | knapweed, brown | Centaurea jacea | B-Regulated |
| Yes | knapweed, diffuse | Centaurea diffusa | B-Regulated |
| Yes | knapweed, meadow | Centaurea x gerstlaueri | B-Regulated |
| No | knapweed, Russian | Rhaponticum repens | B-Regulated |
| Yes | knapweed, spotted | Centaurea stoebe | B-Regulated |
| Yes | kochia | Bassia scoparia | B-Regulated |
| Yes | loosestrife, garden | Lysimachia vulgaris | B-Regulated |
| Yes | loosestrife, purple | Lythrum salicaria | B-Regulated |
| Yes | parrotfeather | Myriophyllum aquaticum | B-Regulated |
| Yes | perennial pepperweed | Lepidium latifolium | B-Regulated |
| Yes | policeman's helmet | Impatiens glandulifera | B-Regulated |
| Yes | rush skeletonweed | Chondrilla juncea | B-Regulated |
| Yes | saltcedar | Tamarix ramosissima | B-Regulated |
| Yes | spurge, leafy | Euphorbia virgata | B-Regulated |
| Yes | starthistle, yellow | Centaurea solstitialis | B-Regulated |
| Yes | sulfur cinquefoil | Potentilla recta | B-Regulated |
| Yes | tansy ragwort3 | Jacobaea vulgaris | B-Regulated |
| Yes | thistle, musk | Carduus nutans | B-Regulated |
| Yes | thistle, plumeless | Carduus acanthoides | B-Regulated |
| Yes | thistle, Scotch | Onopordum acanthium | B-Regulated |
| No | tocalote9n | Centaurea melitensis | B-Regulated |
| Yes | velvetleaf | Abutilon theophrasti | B-Regulated |
| Historically | water primrose | Ludwigia hexapetala | B-Regulated |
| Yes | white bryony | Bryonia alba | B-Regulated |
| Yes | wild basil8a | Clinopodium vulgare | B-Regulated |
| Yes | wild chervil | Anthriscus sylvestris | B-Regulated |
| No | yellow floating heart | Nymphoides peltata | B-Regulated |
| Yes | yellow nutsedge | Cyperus esculentus | B-Regulated |
Regulated Class C weeds
The following Class C weeds have been selected by the King County Weed Board based on potential threat and feasibility of control. Property owners in King County are required to control these species.
| In King County |
Common name |
Scientific name |
Class |
|---|---|---|---|
| Yes | absinth wormwood |
Artemisia absinthium |
C-Regulated |
Non-regulated noxious weeds
Property owners in King County are not required to control the following Class B and C weeds, but control is recommended where feasible due to their impacts. Species that are classified with "selective" require control within specific geographical parameters. See footnotes for details.
| In King County |
Common name |
Scientific name |
Class |
|---|---|---|---|
| Yes | blackberry, cutleaf | Rubus laciniatus | C-Non-Regulated |
| Yes | blackberry, Himalayan | Rubus bifrons | C-Non-Regulated |
| Yes | buffalobur |
Solanum rostratum |
C-Non-Regulated |
| Yes | butterfly bush | Buddleja davidii | B-Non-Regulated |
| Yes | cattail, nonnative species and hybrids (does not include native species common cattail) | Typha angustifolia, T. domingensis, and T. x glauca (and any other nonnative Typha spp.) (does not include native cattail T. latifolia) | C-Non-Regulated |
| No | common barberry | Berberis vulgaris | C-Non-Regulated |
| Yes | common catsear | Hypochaeris radicata | C-Non-Regulated |
| Yes | common fennel | Foeniculum vulgare (excluding F. vulgare var. azoricum) | B-Non-Regulated |
| Yes | common groundsel | Senecio vulgaris | C-Non-Regulated |
| Yes | common hawthorn9b | Crataegus monogyna | C-Non-Regulated |
| Yes | common St. Johnswort4 | Hypericum perforatum | C-Non-Regulated |
| Yes | common tansy | Tanacetum vulgare | B-Non-Regulated |
| Yes | common teasel | Dipsacus fullonum | C-Non-Regulated |
| Yes | curly-leaf pondweed | Potamogeton crispus | C-Non-Regulated |
| Yes | Eurasian watermilfoil | Myriophyllum spicatum | B-Non-Regulated |
| No | Eurasian watermilfoil hybrid | Myriophyllum spicatum x M. sibiricum | C-Non-Regulated |
| Yes | field bindweed | Convolvulus arvensis | C-Non-Regulated |
| Yes | fragrant water lily | Nymphaea odorata | C-Non-Regulated |
| Yes | green alkanet | Pentaglottis sempervirens | C-Non-Regulated |
| Yes | hairy whitetop | Lepidium appelianum | C-Non-Regulated |
| Yes | hanging sedge5 | Carex pendula (ssp. pendula and ssp. agastachys) | B-Selective |
| Yes | hawkweeds; all non-native species and hybrids of the wall subgenus except European hawkweed2 | Hieracium, subgenus Hieracium (except Hieracium sabaudum) | B-Non-Regulated |
| Yes | herb Robert | Geranium robertianum | B-Non-Regulated |
| Yes | hoary cress | Lepidium draba | C-Non-Regulated |
| Yes | ivy, Atlantic | Hedera hibernica | C-Non-Regulated |
| Yes | ivy, English | Hedera helix 'Baltica', Hedera helix 'Pittsburgh', Hedera helix 'Star' | C-Non-Regulated |
| Yes | jubata grass | Cortaderia jubata | C-Non-Regulated |
| Yes | knotweed, hybrid5,9c | Fallopia x bohemica | B-Selective |
| Yes | knotweed, giant5 | Fallopia sachalinensis | B-Selective |
| Yes | knotweed, Himalayan5 | Persicaria wallichii | B-Selective |
| Yes | knotweed, itadori5,9d | Fallopia japonica | B-Selective |
| Yes | lesser celandine | Ficaria verna | B-Non-Regulated |
| Yes | myrtle spurge | Euphorbia myrsinites | B-Non-Regulated |
| Yes | old man's beard | Clematis vitalba | C-Non-Regulated |
| Yes | orange candleflower9o | Arum italicum | C-Non-Regulated |
| Yes | oxeye daisy | Leucanthemum vulgare | C-Non-Regulated |
| Yes | Pampas grass | Cortaderia selloana | C-Non-Regulated |
| Yes | poison hemlock7 | Conium maculatum | B-Selective |
| No | Ravenna grass | Tripidium ravennae | B-Non-Regulated |
| Yes | reed canarygrass | Phalaris arundinacea | C-Non-Regulated |
| Yes | rough chervil5 | Chaerophyllum temulum | B-Selective |
| Yes | scentless mayweed | Tripleurospermum inodorum | C-Non-Regulated |
| Yes | Scotch broom6 | Cytisus scoparius | B-Selective |
| Yes | shiny geranium8b,10 | Geranium lucidum | B-Selective |
| Yes | spotted jewelweed | Impatiens capensis | C-Non-Regulated |
| Yes | spurge laurel | Daphne laureola | B-Non-Regulated |
| Yes | thistle, bull | Cirsium vulgare | C-Non-Regulated |
| Yes | thistle, creeping9e | Cirsium arvense | C-Non-Regulated |
| Yes | tree of heaven | Ailanthus altissima | C-Non-Regulated |
| Yes | ventenata | Ventenata dubia | C-Non-Regulated |
| Yes | white cockle | Silene latifolia | C-Non-Regulated |
| Yes | wild carrot | Daucus carota (excluding ssp. sativus) | C-Non-Regulated |
| Yes | yellow archangel | Lamium galeobdolon | B-Non-Regulated |
| Yes | yellow flag iris | Iris pseudacorus | C-Non-Regulated |
| Yes | yellow toadflax | Linaria vulgaris | C-Non-Regulated |
Weeds of concern
The King County Weed Board also encourages control of non-native, invasive plants that are not on the state noxious weed list but have impacts in King County. Plants on this list are considered Invasive Vegetation in King County's Critical Areas Ordinance (KCC 21A.06.641C). Property owners are not required to control these plants. Education is being provided as authorized by RCW 17.10.090.
| In King County |
Scientific name |
Common name |
Category |
|---|---|---|---|
| Yes | bindweed, nonnative species and hybrids (does not include native hedge bindweed) | Calystegia silvatica ssp. disjuncta, C. x lucana | Weed of Concern |
| Yes | bird cherry | Prunus avium | Weed of Concern |
| Yes | bird's-foot trefoil | Lotus corniculatus | Weed of Concern |
| Yes | bishop's weed | Aegopodium podagraria | Weed of Concern |
| Yes | bittersweet nightshade | Solanum dulcamara | Weed of Concern |
| Yes | black locust | Robinia pseudoacacia | Weed of Concern |
| Yes | bur chervil | Anthriscus caucalis | Weed of Concern |
| Yes | buttercup, creeping | Ranunculus repens | Weed of Concern |
| Yes | buttercup, tall | Ranunculus acris | Weed of Concern |
| Yes | cherry laurel9f | Prunus laurocerasus | Weed of Concern |
| Yes | common holly; English holly8c | Ilex aquifolium | Weed of Concern |
| Yes | European mountain-ash | Sorbus aucuparia | Weed of Concern |
| Yes | harlequin maple; Norway maple8a | Acer platanoides | Weed of Concern |
| Yes | horse chestnut | Aesculus hippocastanum | Weed of Concern |
| Yes | introduced peavines8a | Lathyrus sylvestris, L. latifolius | Weed of Concern |
| Yes | multiflora rose | Rosa multiflora | Weed of Concern |
| Yes | silver lace vine | Fallopia baldschuanica (syn. Polygonum aubertii) | Weed of Concern |
| Yes | vested blackberry | Rubus vestitus | Weed of Concern |
Notes
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.
This tab displays noxious weeds listed alphabetically by their scientific names.
- Class A noxious weeds
- Class B noxious weeds
- Class C noxious weeds
- Non-Regulated noxious weeds
- Weeds of concern
- Notes
Regulated Class A weeds
State law requires property owners to eradicate all Class A species due to potential threat and limited distribution:
| In King County |
Scientific name |
Common name |
Class |
|---|---|---|---|
| Yes | Alliaria petiolata | garlic mustard | A |
| Yes | Brachypodium sylvaticum | false brome | A |
| No | Butomus umbellatus | flowering rush | A |
| No | Carduus cinereus | thistle, ashen9l | A |
| No | Carduus pycnocephalus | thistle, shore9m | A |
| No | Carduus tenuiflorus | thistle, slenderflower | A |
| No | Centaurea calcitrapa | purple starthistle | A |
| Yes | Centaurea macrocephala | knapweed, bighead | A |
| No | Clematis orientalis | orange peel clematis9i | A |
| Yes | Crupina vulgaris | common crupina | A |
| Yes | Euphorbia oblongata | eggleaf spurge | A |
| Yes | Galega officinalis | goatsrue | A |
| Yes | Genista monspessulana | French broom | A |
| Yes | Glyceria maxima | reed sweetgrass | A |
| No | Helianthus ciliaris | Texas blueweed | A |
| Yes | Heracleum mantegazzianum | giant hogweed | A |
| Historically |
Hydrilla verticillata | hydrilla | A |
| Yes | Impatiens parviflora | small-flowered jewelweed | A |
| No | Isatis tinctoria | dyers woad | A |
| Yes | Limnobium laevigatum | smooth frogbit9k | A |
| Yes | Ludwigia peploides | floating primrose-willow | A |
| No | Mirabilis nyctaginea | wild four o'clock | A |
| No | Myriophyllum heterophyllum | variable-leaf milfoil | A |
| No | Pueraria montana var. lobata | kudzu | A |
| No | Salvia aethiopis | sage, Mediterranean | A |
| No | Salvia pratensis | meadow clary | A |
| Historically |
Salvia sclarea | sage, clary | A |
| Yes | Schoenoplectus mucronatus | ricefield bulrush | A |
| Yes | Silybum marianum | thistle, milk | A |
| No | Solanum elaeagnifolium | silverleaf nightshade | A |
| No | Sorghum halepense | Johnsongrass | A |
| No | Spartina alterniflora | cordgrass, smooth | A |
| Yes | Spartina anglica | cordgrass, common | A |
| No | Spartina densiflora | cordgrass, dense flowered | A |
| No | Spartina patens | cordgrass, salt meadow | A |
| Yes | Spartium junceum | rush broom9j | A |
| No | Zygophyllum fabago | bean-caper9g | A |
Regulated Class B weeds
Regulated in counties where they are limited in distribution or a local priority. The following Class B weeds have been designated by the State Weed Board or selected by the King County Weed Board. Property owners in King County are required to control these species.
| In King County |
Scientific name |
Common name |
Class |
|---|---|---|---|
| Yes | Abutilo theophrasti | velvetleaf | B-Regulated |
| Yes | Alhagi maurorum | camelthorn | B-Regulated |
| No | Amorpha fruticosa | indigobush | B-Regulated |
| Yes | Anchusa officinalis | bugloss, common | B-Regulated |
| Yes | Anthriscus sylvestris | wild chervil | B-Regulated |
| Yes | Bassia scoparia | kochia | B-Regulated |
| No | Berteroa incana | hoary alyssum | B-Regulated |
| Yes | Bryonia alba | white bryony | B-Regulated |
| No | Cabomba caroliniana | fanwort | B-Regulated |
| Yes | Carduus acanthoides | thistle, plumeless | B-Regulated |
| Yes | Carduus nutans | thistle, musk | B-Regulated |
| Yes | Centaurea diffusa | knapweed, diffuse | B-Regulated |
| Yes | Centaurea x gerstlaueri | knapweed, meadow | B-Regulated |
| Historically | Centaurea jacea | knapweed, brown | B-Regulated |
| No | Centaurea melitensis | tocalote9n | B-Regulated |
| No | Centaurea nigra | knapweed, black | B-Regulated |
| Yes | Centaurea solstitialis | starthistle, yellow | B-Regulated |
| Yes | Centaurea stoebe | knapweed, spotted | B-Regulated |
| Yes | Chondrilla juncea | rush skeletonweed | B-Regulated |
| Yes | Clinopodium vulgare | wild basil8a | B-Regulated |
| Yes | Cynoglossum officinale | houndstongue | B-Regulated |
| Yes | Cyperus esculentus | yellow nutsedge | B-Regulated |
| Yes | Echium vulgare | blueweed; viper's bugloss | B-Regulated |
| Yes | Egeria densa | Egeria1,9a | B-Regulated |
| Yes | Epilobium hirsutum | hairy willow-herb | B-Regulated |
| Yes | Euphorbia virgata | spurge, leafy | B-Regulated |
| Yes | Hieracium aurantiacum | hawkweed, orange | B-Regulated |
| Yes | Hieracium sabaudum | hawkweed, European | B-Regulated |
| Yes | Hieracium, subgenus Pilosella | hawkweeds: all non-native species and hybrids of the meadow subgenus2 | B-Regulated |
| Yes | Impatiens glandulifera | policeman's helmet | B-Regulated |
| Yes | Jacobaea vulgaris | tansy ragwort3 | B-Regulated |
| Yes | Lepidium latifolium | perennial pepperweed | B-Regulated |
| Yes | Linaria dalmatica ssp. dalmatica | Dalmatian toadflax | B-Regulated |
| Historically | Ludwigia hexapetala | water primrose | B-Regulated |
| Historically | Lycopsis arvensis | bugloss, annual | B-Regulated |
| Yes | Lysimachia vulgaris | loosestrife, garden | B-Regulated |
| Yes | Lythrum salicaria | loosestrife, purple | B-Regulated |
| Yes | Myriophyllum aquaticum | parrotfeather | B-Regulated |
| No | Nymphoides peltata | yellow floating heart | B-Regulated |
| Yes | Onopordum acanthium | thistle, Scotch | B-Regulated |
| Yes | Phragmites australis | common reed (non-native genotypes) | B-Regulated |
| No | Picris hieracioides | hawkweed oxtongue | B-Regulated |
| Yes | Potentilla recta | sulfur cinquefoil | B-Regulated |
| No | Rhaponticum repens | knapweed, Russian | B-Regulated |
| No | Sagittaria graminea | grass-leaved arrowhead | B-Regulated |
| Yes | Tamarix ramosissima | saltcedar | B-Regulated |
| Yes | Tussilago farfara | European coltsfoot | B-Regulated |
| Yes | Ulex europaeus | gorse | B-Regulated |
Regulated Class C weeds
The following Class C weeds have been selected by the King County Weed Board based on potential threat and feasibility of control. Property owners in King County are required to control these species.
| In King County |
Scientific name |
Common name | Class |
|---|---|---|---|
| Yes | Artemisia absinthium |
absinth wormwood |
C-Regulated |
Non-Regulated noxious weeds
Property owners in King County are not required to control the following Class B and C weeds, but control is recommended where feasible due to their impacts. Species that are classified with "selective" require control within specific geographical parameters. See footnotes for details.
| In King County |
Scientific name |
Common name |
Class |
|---|---|---|---|
| Yes | Ailanthus altissima | tree of heaven | C-Non-Regulated |
| Yes | Arum italicum | orange candleflower9o | C-Non-Regulated |
| No | Berberis vulgaris | common barberry | C-Non-Regulated |
| Yes | Buddleja davidii | butterfly bush | B-Non-Regulated |
| Yes | Carex pendula (ssp. pendula and ssp. agastachys) | hanging sedge5 | B-Selective |
| Yes | Chaerophyllum temulum | rough chervil5 | B-Selective |
| Yes | Cirsium arvense | thistle, creeping9e | C-Non-Regulated |
| Yes | Cirsium vulgare | thistle, bull | C-Non-Regulated |
| Yes | Clematis vitalba | old man's beard | C-Non-Regulated |
| Yes | Conium maculatum | poison hemlock7 | B-Selective |
| Yes | Convolvulus arvensis | field bindweed | C-Non-Regulated |
| Yes | Cortaderia jubata | jubata grass | C-Non-Regulated |
| Yes | Cortaderia selloana | Pampas grass | C-Non-Regulated |
| Yes | Crataegus monogyna | common hawthorn9b | C-Non-Regulated |
| Yes | Cytisus scoparius | Scotch broom6 | B-Selective |
| Yes | Daphne laureola | spurge laurel | B-Non-Regulated |
| Yes | Daucus carota (excluding ssp. sativus) | wild carrot | C-Non-Regulated |
| Yes | Dipsacus fullonum | common teasel | C-Non-Regulated |
| Yes | Euphorbia myrsinites | myrtle spurge | B-Non-Regulated |
| Yes | Fallopia x bohemica | knotweed, hybrid5,9c | B-Selective |
| Yes | Fallopia japonica | knotweed, itadori5,9d | B-Selective |
| Yes | Fallopia sachalinensis | knotweed, giant5 | B-Selective |
| Yes | Ficaria verna | lesser celandine | B-Non-Regulated |
| Yes | Foeniculum vulgare (excluding F. vulgare var. azoricum) | common fennel | B-Non-Regulated |
| Yes | Geranium lucidum | shiny geranium8b,10 | B-Selective |
| Yes | Geranium robertianum | herb Robert | B-Non-Regulated |
| Yes | Hedera helix 'Baltica', Hedera helix 'Pittsburgh', Hedera helix 'Star' | ivy, English | C-Non-Regulated |
| Yes | Hedera hibernica | ivy, Atlantic | C-Non-Regulated |
| Yes | Hieracium, subgenus Hieracium (except Hieracium sabaudum) | hawkweeds; all non-native species and hybrids of the wall subgenus except European hawkweed2 | B-Non-Regulated |
| Yes | Hypericum perforatum | common St. Johnswort4 | C-Non-Regulated |
| Yes | Hypochaeris radicata | common catsear | C-Non-Regulated |
| Yes | Impatiens capensis | spotted jewelweed | C-Non-Regulated |
| Yes | Iris pseudacorus | yellow flag iris | C-Non-Regulated |
| Yes | Lamium galeobdolon | yellow archangel | B-Non-Regulated |
| Yes | Lepidium appelianum | hairy whitetop | C-Non-Regulated |
| Yes | Lepidium draba | hoary cress | C-Non-Regulated |
| Yes | Leucanthemum vulgare | oxeye daisy | C-Non-Regulated |
| Yes | Linaria vulgaris | yellow toadflax | C-Non-Regulated |
| Yes | Myriophyllum spicatum | Eurasian watermilfoil | B-Non-Regulated |
| No | Myriophyllum spicatum x M. sibiricum | Eurasian watermilfoil hybrid | C-Non-Regulated |
| Yes | Nymphaea odorata | fragrant water lily | C-Non-Regulated |
| Yes | Pentaglottis sempervirens | green alkanet | C-Non-Regulated |
| Yes | Persicaria wallichii | knotweed, Himalayan5 | B-Selective |
| Yes | Phalaris arundinacea | reed canarygrass | C-Non-Regulated |
| Yes | Potamogeton crispus | curly-leaf pondweed | C-Non-Regulated |
| Yes | Rubus armeniacus | blackberry, Himalayan | C-Non-Regulated |
| Yes | Rubus laciniatus | blackberry, evergreen | C-Non-Regulated |
| Yes | Senecio vulgaris | common groundsel | C-Non-Regulated |
| Yes | Silene latifolia | white cockle | C-Non-Regulated |
| Yes | Solanum rostratum |
buffalobur |
C-Regulated |
| Yes | Tanacetum vulgare | common tansy | B-Non-Regulated |
| No | Tripidium ravennae | Ravenna grass | B-Non-Regulated |
| Yes | Tripleurospermum inodorum | scentless mayweed | C-Non-Regulated |
| Yes | Typha angustifolia, T. domingensis, and T. x glauca (and any other nonnative Typha spp.) (does not include native cattail T. latifolia) | cattail, nonnative species and hybrids (does not include native species common cattail) | C-Non-Regulated |
| Yes | Ventenata dubia | ventenata | C-Non-Regulated |
Weeds of concern
The King County Weed Board also encourages control of non-native, invasive plants that are not on the state noxious weed list but have impacts in King County. Plants on this list are considered Invasive Vegetation in King County’s Critical Areas Ordinance (KCC 21A.06.641C). Property owners are not required to control these plants. Education is being provided as authorized by RCW 17.10.090.
| In King County |
Scientific name |
Common name |
Category |
|---|---|---|---|
| Yes | Acer platanoides | harlequin maple; Norway maple8a | Weed of Concern |
| Yes | Aegopodium podagraria | bishop's weed | Weed of Concern |
| Yes | Aesculus hippocastanum | horse chestnut | Weed of Concern |
| Yes | Anthriscus caucalis | bur chervil | Weed of Concern |
| Yes | Calystegia silvatica ssp. disjuncta, C. x lucana | bindweed, nonnative species and hybrids (does not include native hedge bindweed) | Weed of Concern |
| Yes | Fallopia baldschuanica (syn. Polygonum aubertii) | silver lace vine | Weed of Concern |
| Yes | Ilex aquifolium | common holly; English holly8c | Weed of Concern |
| Yes | Lathyrus sylvestris, L. latifolius | introduced peavines8a | Weed of Concern |
| Yes | Lotus corniculatus | bird's-foot trefoil | Weed of Concern |
| Yes | Prunus avium | bird cherry | Weed of Concern |
| Yes | Prunus laurocerasus | cherry laurel9f | Weed of Concern |
| Yes | Ranunculus acris | buttercup, tall | Weed of Concern |
| Yes | Ranunculus repens | buttercup, creeping | Weed of Concern |
| Yes | Robinia pseudoacacia | black locust | Weed of Concern |
| Yes | Rosa multiflora | multiflora rose | Weed of Concern |
| Yes | Rubus vestitus | vested blackberry | Weed of Concern |
| Yes | Solanum dulcamara | bittersweet nightshade | Weed of Concern |
| Yes | Sorbus aucuparia | European mountain-ash | Weed of Concern |
Notes
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.