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king devil hawkweed (Hieracium pratense)
NOT KNOWN TO OCCUR IN OREGON PLEASE CALL 1-866-INVADER IF YOU SUSPECT YOU HAVE FOUND THIS SPECIES
USDA Symbol:  HIPI2

ODA rating: A
King devil hawkweed risk assessment
Noxious weed listing process
 

Other common names
tall hawkweed, yellow king devil hawkweed
 
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Images courtesy of Wisconsin State Herberium

 
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
 
Description
Perennial; flowers June to July in lower elevations. Grows 10 to 36 inches tall. Leaves are hairy, spatula shaped and almost exclusively basal. Flower heads are clustered, yellow, 1/2 wide, and number up to 30 per plant. Extensive stolons form dense mats of vegetation. King-devil hawkweed (H. piloselloides), yellow hawkweed (H. floribundum) and meadow hawkweed (H. pratense) are all very similar and difficult to classify. Native hawkweeds have numerous stem leaves, lack stolons and generally have solitary flowers.
 
Impacts
Plants of the hawkweed complex produce mats of rosettes that prevent desirable plants from establishing or surviving. Hawkweeds dominate sites by out-competing other species for water and nutrients and by releasing alleopathic compounds from their own decaying leaves. They grow well in moist sunny grassy areas, but do tolerate shade in some areas. They are becoming troublesome weeds in native meadows, prairies, pastures and lawns. Wilderness areas in the Pacific Northwest are at risk of invasion.
 
Distribution in Oregon
This species is not yet known to occur in Oregon.
 
Biological controls
Biological control agents are not used on "A" listed weeds in Oregon. If this weed is found in the state it will be managed for eradication or containment.
 
Informational links:
Oregon WeedMapper