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Meadow hawkweed subgenus identification and control
Information about the noxious weeds in the meadow hawkweed subgenus. Meadow Hawkweed subgenus is also known by its Latin name, Hieracium, subgenus Pilosella.
About this weed
The species in the meadow hawkweed subgenus are regulated Class B noxious weeds in King County. This means control is required in King County under the state noxious weed law. Meadow hawkweed subgenus is also on the Washington quarantine list and it is illegal to buy or sell them in the state.
The meadow hawkweed subgenus is known as Hieracium, subgenus Pilosella and it is in the aster (daisy) family. These introduced species of hawkweed are native to Europe. They were transported to the United States as herbal remedies and ornamentals. Nonnative hawkweeds in subgenus Pilosella include whiplash (Hieracium flagellare), yellowdevil (H. x floribundum), yellow or meadow (H. caespitosum), queen-devil (H. glomeratum), pale (H. lactucella), mouseear (H. pilosella), and tall (H. piloselloides). Orange hawkweed (H. aurantiacum) is also in this subgenus but is listed separately on the state noxious weed list because of its distinctive orange flowers.
Why it's a problem
Members of the meadow hawkweed subgenus spread readily and have negative impacts to rangeland and other habitats, especially in mid to upper elevations and in areas with low fertility soils. Many species spread by creeping roots as well as seed and form large monocultures (large areas filled with one species of plant) that can suppress grasses and other plants needed as forage by wildlife and range animals.
Plant description
General characteristics of hawkweeds
Traits of non-native hawkweeds:
- All perennials (plants that have a 2+ year life cycle)
- Many non‐native hawkweeds have stolons (horizontal plant stems that root and form new plants), but no native Washington hawkweed species have stolons
- They contain a milky juice
- Flowers are dandelion‐like and yellow or orange
- Leaves and stems are covered with bristly hairs
- Plants have rosettes (a circular cluster of leaves on ground level)
- The leaves of most hawkweeds persist through flowering
Traits of meadow hawkweed subgenus
Distinguishing traits of meadow hawkweed subgenus:
- Leaves have smooth margins or only a little toothed
- Stems are hairy and often leafless
- Most have creeping stolons
- Distinct clusters of flower buds with black hairs
- Flowers are yellow or orange, clustered at the top of the stem
Be aware of look-alike plants
The meadow hawkweed subgenus can be confused with the wall (Hieracium) hawkweed subgenus. To compare the two groups, wall hawkweeds typically do not have stolons like many meadow hawkweeds. They do have stem leaves while meadow hawkweeds usually do not. And the leaf edges are toothed or lobed rather than smooth like meadow hawkweeds.
When in doubt, take photos and share them with us or report them on iNaturalist or EDDMapS.
What to do if you find it
Property owners are required to control meadow hawkweed subgenus on lands that they manage. Please notify us if you see any of these plants growing in King County. Our program staff can provide the property owner or appropriate public agency with site-specific advice on how best to remove it. We map all known locations of regulated noxious weeds in order to help us and others locate new infestations in time to control them.
Control methods
In areas with few weeds, it is important to act quickly before they become harder to control. Make a long-term plan as it often takes several years to get rid of most weeds. Start in the least infested areas first and then move into more heavily infested areas. To reduce costs and environmental impacts, please consider a combination of methods. King County’s best management practices have more detailed information for control of hawkweeds.
Small infestations
If there are only a few plants, hand pulling is an option, but the entire root must be removed. Adding fertilizer or managing soil fertility may also be effective for small populations of hawkweed.
Large infestations
Spot spraying with selective herbicides can be effective, but cleared areas may become reinfested. To compete with any new weeds, consider replanting cleared areas with desirable species. Apply to plants in spring or early summer when they are actively growing and before flowering. Flowering plants can go to seed after being sprayed. Continue checking the area for new plants for several years. Always read the label before using herbicide and follow state and local regulations.
For specific chemical recommendations, please refer to the PNW Pest Management Handbook.
Disposal instructions
Bag all flower heads. If the plants already have seeds, carefully cut the seed head and place in a bag before pulling plants. Dispose of in the household garbage or take to a transfer station. Do not compost or put in yard waste. Never dump plant material in parks or natural areas because weeds can spread from yard waste piles.
Washington State Noxious Weed Control Board pamphlet on noxious weed disposal