king devil hawkweed (Hieracium pratense)
ODA rating: A
Other common names
tall hawkweed, yellow king devil hawkweed
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.
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Images courtesy of Wisconsin State Herberium
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Distribution in Oregon
This species is not yet known to occur in Oregon.
Map legend
Yellow: limited distribution
Red: abundant
Grey: not known to be present
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
WeedMapper
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