Tillamook County Soil and Water Conservation District

Common Weeds of Tillamook County

Note: The links below go to external websites and are intended to provide information only.  If you have any further questions or would like assistance handling a weed infestation on your property, please contact the Tillamook County Soil and Water Conservation District Weed Program Coordinator.

Oregon Department of Agriculture lists ‘noxious’ weeds as being either “A” or “B” listed, and those definitions are listed below:

“A” Listed Weed: – a weed of known economic importance which occurs in Oregon in small enough infestations to make eradication or containment possible; or is not known to occur, but its presence in neighboring states make future occurrence here seem imminent.

“B” Listed Weed – a weed of economic importance which is regionally abundant but which may have limited distribution in some counties.


This list constitutes the bulk of the species that Tillamook County SWCD is monitoring for and taking action against.  It is by no means comprehensive.  Plants of this list are either currently in the county and are problematic, or they are in neighboring counties.

PhotoCommon & Scientific NameODA ListPrevalenceWhy it is a problem
English Ivy

English Ivy

English Ivy (Hedera helix)B ListNearly ubiquitous in Tillamook CountyPromotes erosion and kills trees
Garlic Mustard

Garlic Mustard

Garlic Mustard (Alliaria petiolata)B ListNot common in Tillamook County, but problematic elsewhereSpreads through prolific seed production and plant pieces being moved around.
Giant Hogweed

Giant Hogweed

Giant Hogweed (Heracleum mantegazzianum)A ListAt least one known site in Tillamook CountyGiant Hogweed is increadibly invasive in riparian areas, but can grow in many habitats. The sap is toxic and can severly burn your skin if exposed to sunlight.
galega officinalis


Goats-rue (Galega officinalis)A ListFound in neighboring countyIs is not yet established in Tillamook County, but is highly invasive.


Gorse (Ulex europaeus)B ListLimited to a few known sites in Tillamook County.Gorse is basically scotch broom with thorns, plus it is highly flammable.
italian arum

Italian Arum

Italian Arum (Arum italicum)Not listedCommon horticultural plant, a few incidental sightings.Spreads via tubers and very difficult to remove once established.
Japanese knotweed

Japanese Knotweed

Japanese Knotweed (Fallopia japonica)B ListUbiquitous in waterways in North Tillamook County, less well-established in south Tillamook County.Prevents trees from re-seeding stream sides, causes erosion, alters nutrient cycling and can damage building foundations.
lesser celandine

Lesser Celandine

Lesser Celandine (ranunculus ficaria)B ListOne reported site in Tillamook CountyPersists due to mini tuber production and not yet established in Tillamook County.

Mouse-ear Hawkweed

Mouse-ear Hawkweed (Hieracium pilosella)A ListFound in neighboring countyIt is not yet established in Tillamook county, but is highly invasive.
Old Man's Beard (Clematis Vitalba)

Old Man's Beard

Old Man's Beard (Clematis vitalba)B ListFound in neighboring coutniesIt over-tops and kills trees
orange hawkweed

Orange Hawkweed

Orange Hawkweed (Heiracium aurantiacum)A ListFound in neighboring countyIt is not yet established in Tillamook County, but is highly invasive.
policemans helmet

Policeman's Helmet

Policeman's Helmet (Impatiens glandulifera)B ListBecoming established in Tillamook County. Many large populations have been observed.It displaces other plants and its shallow roots don't hold the river banks that it colonizes.

Purple Loosestrife

Purple Loosestrife (Lythrum salicaria)B ListLimited to a few site in Tillamook CountyIt forms dense monocultures in wetlands and displaces wildlife.

Scotch Broom

Scotch Broom (Cytisus scoparius)B ListExtremely common weedy shrub, has long-lived seedsOnce a seed bank is established, it can last for over 50 years.


Coltsfoot (Tussilago farfara)A ListPreviously found in neighboring countyIt is not yet established in Tillamook County, but is highly invasive.


Vinca (Vinca minor)B ListCommon landscaping plant, used as ground cover.It frequently escapes and creates dense monocultures.

Water Primrose

Water Primrose (Ludwigia peploides)B ListFound in neighboring countiesReduces oxygen levels in water and displaces native species.

Yellow Archangel

Yellow Archangel (Lamiastrum galeobdolon)B ListFairly common ornamental weed in Tillamook County.Spreads into forest understory and can grow from cutting and yard waste.
yellow flag iris

Yellow Flag Iris

Yellow Flag Iris (Iris pseudacorus)B ListCommon riparian area weedIt tends to take over sensitive habitat in estuaries and slow moving waterways.
nymphoides peltata-2

Yellow Floating Heart

Yellow Floating Heart (Nymphoides pelata)B ListFound in neighboring county.It is not yet established in our county, but is highly invasive.
WATCH LIST The species below are not officially listed as noxious weeds, but have characteristics of invasive species or are invasive in other areas with similar climates to our own in Tillamook County.

Japanese Coltsfoot

Japanese Coltsfoot (Petasites japonicus)Not Listed2 known sites, spreads in shady locations.It spreads through a shallow root system and thrives in shaded environments.
Darwin's Barberry

Darwin's Barberry

Darwin's Barberry (Berberis darwinii)Not ListedA few plants have been observed away from their original plantings.Problematic in New Zealand where the climate is similar to Tillamook County.