Tall hawkweed identification and control
Hieracium piloselloides Asteracae Family
History and impactyellow hawkweed and queen-devil hawkweed.
Legal status in King County, Washington
Public and private landowners are required to control infestations of tall hawkweed on their property in King County. Tall hawkweed is a Class B Noxious Weed in Washington, in the group of hawkweeds known as meadow hawkweeds (in the subgenus Pilosella). Tall hawkweed was first added to the weed list in 2013. Meadow hawkweeds are designated for required control in King County by the Washington State Noxious Weed Control Board and as a group are on the list of Regulated Class B Noxious Weeds in King County. For more information, see Noxious Weed Lists and Laws or visit the website of the Washington State Noxious Weed Control Board.
Identification (see below for additional photos)
- Resembles a tall, leggy dandelion with many small flowers in a loose cluster near the tops of the stems
- Stems and flowers are somewhat hairy
- Plant exudes a milky sap when stems or leaves are broken
- Leaves are mostly found at the base of the plant, with a few leaves on the stems
- Leaves are narrow, smooth on the upper surface and hairy along the edges and the mid-rib on the underside.
Growth and habitat
Tall hawkweed has a shallow root system and underground creeping stems called rhizomes. New plants can arise from buds on the rhizomes and on the roots. Tall hawkweed does not form stolons like some of the other yellow-flowered non-native hawkweeds. Tall hawkweed is a perennial and spreads by seeds, root buds and rhizomes. It usually flowers in June and July and sets seed by August.
Tall hawkweed is mostly found in low-nutrient, coarse soils, particularly along roadsides and in outwash areas. It has been documented in King, Snohomish, Cowlitz and Grays Harbor counties.
- Washington State Noxious Weed Control Board (external link)
- Hawkweed weed alert (1.76 MB Acrobat file)
- Hawkweed Best Management Practices (82 KB Acrobat file)
- University of Washington Burke Museum Herbarium (external link)
What to do if you find this plant in King County, Washington
Please notify us if you see tall hawkweed 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. Also, because tall hawkweed is not well-established in King County, we have an opportunity to stop it from spreading if we act quickly. We map all known locations of regulated noxious weeds such as tall hawkweed in order to help us and others locate new infestations in time to control them.
Tall hawkweed photos
Report tall hawkweed in King County, Washington
- Please notify us through our online infestation form
Locate tall hawkweed in King County, Washington
- Use our interactive noxious weed map and search for yellow hawkweed