Noxious Weeds

Spartina Update

Class A Noxious Weed – Law Requires Eradication

Spartina anglica is a non-native invasive plant species found in the intertidal zone of North Puget Sound. Referred to as a bioengineer, the plant is able to accrete sediments, altering elevation. The result of this increased elevation can be as dramatic as creating a salt march where a mud flat once existed. This can cause major disruptions to native marine habitat.Photo of spartina, a class A noxious weed

Intentionally introduced as a shoreline stabilizer in the early 1960s, spartina was believed to be sterile. Only after firm establishment was it discovered that spartina reproduced vegetatively as well as through viable seed production. Drift card studies indicate that spartina seeds and root fragments quite likely spread from Port Susan Bay to the Hood Canal region and from the Georgia Basin, near Vancouver, B.C., to North Puget Sound. In 1975, the total infestation of North Puget Sound was estimated to total less than 15 acres. By 1997, there were approximately 430 solid acres of spartina found in seven North Puget Sound counties.

The Island County Noxious Weed Control Board began treating Spartina in 1997. At that time, there was more infested acres of spartina in Island County than in any other county in North Puget Sound. At the height of infestation, Island County had approximately 250 solid acres of dpartina. Today,  fewer than 5 acres of spartina remain.

How You Can Help Eradicate Spartina

  • Educate yourself, your neighbors and your friends.
  • Learn to Identify spartina. Inform your neighbors and friends about the problems associated with this species.
  • Walk the beach.
  • If you don’t own property along the water, walk your favorite beach, or explore a new one. Look for seedlings as well as clones. Report what you find to the Weed Control Office.
  • Dig it up.

Mechanical control of Spartina using a garden fork or shovel has proven to be incredibly effective. It is very important that care be taken to remove all roots and fragments. Take a bucket and dispose of the plants above the high water mark.


While there are several chemicals that are safe, effective and legal, the application of herbicides to aquatic environments is strictly controlled. Appropriate licenses and permits must be obtained before herbicides may be applied in these environments.

Pictorial Index - Click on Images for More Information

Class A Noxious Weeds - Required to Eradicate

purple starthistle

Centaurea calcitrapa

meadow clary

Salvia pratensis

thistle, milk

Silybum marianum

Spanish broom

Spartium junceum

knapweed, bighead

Centaurea macrocephala

giant hogweed

Heracleum mantegazzianum

garlic mustard

Allaria petiolata

cordgrass, densflowered

Spartina densiflora

safe, clary

Salvia sclarea

cordgrass, common


Class B Noxious Weeds - Asked to Control

spurge laurel

Daphne laureola

Brazilian elodea

Egeria densa


Buddleja davidii

common fennel

Foeniculum vulgare

common reed (non-native genotypes)

Phragmites australis

Dalmatian toadflax

Linaria dalmatica ssp. dalmatica

Eurasian watermilfoil

Myriophyllum spicatum


Ulex europaeus

hairy willowherb

Epilobium hirsutum

hawkweed, orange

Hieracium aurantiacum

Hawkweed, yellow

Hieracium caespitosum


Geranium robertianum

knapweed, brown

Centaurea jacea

knapweed, diffuse

Centaurea diffusa

knapweed, meadow

Centaurea jacea x nigra

knapweed, spotted

Centaurea stoebe

knotweed, Bohemian

Polygonum x bohemicum

knotweed, giant

Polygonum sachalinense

knotweed, Himalayan

Polygonum polystachyum

knotweed, Japanese

Polygonum cuspidatum

More Class B Noxious Weeds - Asked to Control

loosestrife, purple

Lythrum salicaria


Myriophyllum aquaticum

poison hemlock

Conium maculatum

Scotch broom

Cytisus scoparius

sulfur cinquefoil


tansy ragwort

Senecio jacobaea

thistle, musk

Carduus nutans


Abutilon theophrasti

wild chervil

Anthriscus sylvestris

yellow archangel

Lamiastrum galeobdolon

Class C Noxious Weeds

bull thistle

Cirsium vulgare

Canada thistle

Cirsium arvense

absinth wormwood

Artemisia absinthium


Gypsophila paniculata


Solanum rostratum

common catsear

Hypochaeris radicata


Clematis vitalba

common groundsel

Senecio vulgaris

common St. Johnswort

Hypericum perforatum

common tansy

Tanacetum vulgare

common teasel

Dipsacus fullonum

curlyleaf pondweed

Potamogeton crispus

English ivy – four cultivars only

Hedera helix ‘Baltica’, ‘Pittsburgh’, and ‘Star’ H. hibernica ‘Hibernica’

evergreen blackberry

Rubus laciniatus

field bindweed

Convolvulus arvensis

Himalayan blackberry

Rubus armeniacus

Italian arum

Arum italicum

Japanese eelgrass

Zostera japonica

More Class C Noxious Weeds

jubata grass

Cortaderia jubata


Clematis vitalba

oxeye daisy

Leucanthemum vulgare

pampas grass

Cortaderia selloana

reed canarygrass

Phalaris arundinacea

scentless mayweed

Matricaria perforata

smoothseed alfalfa dodder

Cuscuta approximata

wild carrot

Daucus carota

yellowflag iris

Iris pseudacorus

yellow toadflax

Linaria vulgaris

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