Meadow hawkweed subgenus identification and control
Hieracium, subgenus Pilosella, Asteraceae Family
Hawkweeds are dandelion-like plants that are generally hairy, with clusters of small yellow or orange dandelion-like flowerheads, mostly basal leaves, and often creeping stolons or rhizomes. Stems exude a milky sap when broken and plants have white and/or black hairs on the stems, leaves and flowerheads. The meadow group of hawkweeds are distinguished by strap-shaped leaves that are not obviously toothed, flowerheads that are generally in compact clusters on tops of mostly leafless, hairy stems, and the presence of creeping stolons (runners). Flowerheads generally have black hairs that are especially noticeable on the tightly packed, round flower buds.
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. Nonnative hawkweed species can be difficult to tell apart, especially if they hybridize.
On the state noxious weed list, the nonnative yellow flowered hawkweeds are grouped into two Class B noxious weed listings by subgenus Pilosella (meadow group) and subgenus Hieracium (wall group). Nonnative hawkweeds in 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). Orange hawkweed (H. aurantiacum) is also in this subgenus but is listed separately on the state noxious weed list because of its distinctive orange flowers. All species in this group are Class B noxious weeds designated by the State Noxious Weed Board for required control in King County.
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