Hawkweed Oxtongue
Picris hieracioides
Washington State Classification
Class B — Control Required (Designated)
Hawkweed oxtongue is weedy in other parts of the United States and is closely related to another noxious weed in California.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Hawkweed oxtongue is an annual, biennial or perennial plant with upright, branching stems reaching 1 to 2.4 feet tall. Stems have a milky juice.
Leaves
It has basal and stem leaves. Basal leaves may have stalks (petioles) and are narrow to narrowly oval with smooth or rounded teeth or lobed margins, up to 11.8 inches long. Leaf face with bristled hairs that have hooked tips. Stem leaves without stalks.
Flowers
Flower heads on short stems in spreading clusters, each one about .5 inch to .8 inch in diameter. Flower heads have yellow ray (ligulate) flowers. Flower head base is covered in bracts of unequal size, the outer ones spreading and bristly.
Fruit & Seeds
Seeds are small, about .1 inch long with 5 to 10 ribs, reddish brown in color. Seeds have a feathery pappus attached to one end to aid in dispersal.
Impact
Hawkweed oxtongue is weedy in other parts of the United States and is closely related to another noxious weed in California. Only a limited amount has been found in Washington.
Ecology & Spread
Habitat
Only known to occur in Skamania County, hawkweed oxtongue can grow along pond edges, meadows, grain fields, cultivated fields, clear cuts and waste places like old quarries. Please click here to see a county level distribution map of hawkweed oxtongue in Washington.
Spread Mechanisms
Reproduction
Oxtongue hawkweed reproduces by seed.
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Control Methods
Mechanical
- Hand-pulling or grubbing out small, new infestations should be effective.
Cultural / Prevention
- Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.