Nonnative Hawkweed Species & Hybrids of Meadow Subgenus
Hieracium subgenus Pilosella
Washington State Classification
Class B — Control Required (Designated)
These nonnative hawkweed species and hybrids are invasive, spread readily, and have negative impacts to rangeland and other habitats, especially in mid to upper elevations and in areas with low fertility soils.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Perennial, herbaceous plants that exude a milky sap when broken, have various types of hairs, and have flowerheads of yellow flowers. Nonnative hawkweed species can be difficult to tell apart, especially if they hybridize. The nonnative yellow flowered hawkweeds are grouped into two Class B noxious weed listings by subgenus Pilosella and subgenus Hieracium. Nonnative hawkweeds in meadow 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).
Leaves
Plants in this subgenus typically have basal leaves and few to no stem leaves. Leaf edges are smooth or minutely toothed.
Flowers
Flowerheads are composed of all yellow ray flowers (dandelion-like). Bracts at base of flowerheads have various types of hairs. Flowerheads can be solitary (as with mouseear hawkweed) but generally are in clusters.
Fruit & Seeds
Seeds are small, with ribs or grooves and have bristles on one end.
Impact
These nonnative hawkweed species and hybrids are invasive, spread readily, and have negative impacts to rangeland and other habitats, especially in mid to upper elevations and in areas with low fertility soils.
Ecology & Spread
Habitat
Typically found in fields, meadows, pastures, forest clearings and disturbed areas such as roadsides and abandoned farmland. Please click here to see a county level distribution map of nonnative hawkweed species and hybrids of meadow subgenus in Washington.
Spread Mechanisms
Reproduction
Plants can spread by roots, stolons and by seed.
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Control Methods
Mechanical
- Mechanically controlling hawkweed species can be difficult to do in pastures and rangelands. Mowing plants to get rid of flowerheads only stimulates vegetative growth. If there are only a few plants, hand digging is a feasible option, but all of the roots must be removed. Once plants are dug up, put them into a city yard waste container or throw them in the trash. Do not put pulled plants in home compost piles as they might not get hot enough to kill them, and many species can vegetatively spread.
Cultural / Prevention
- Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.