Invasive Species: Hieracium aurantiacum, Orange Hawkweed
Orange hawkweed is an invasive perennial plant that can grow up to 11.8 to 23.6 in. (30 to 60 cm) tall and produces a milky sap. Leaves are mostly basal, elliptical, 2 to 8 in. (5 to 20 cm) long, 0.4 to 1.2 in. (1 to 3 cm) wide, and covered with short, stiff, black hairs. Flowers are orange to red, have square-edged petals, and appear in May to June on leafless flower stalks. Dandelion-like fruit have a white pappus attached that aids in wind dispersal. Orange hawkweed is native to Europe and occurs in grasslands.
What are invasive species and why should we be concerned about them?
Taxonomy: Scientific and Common Names for This Species
Asterales > Asteraceae > Hieracium aurantiacum L.
Hieracium aurantiacum – USDA PLANTS Profile
Distribution Maps
Orange hawkweed – The reported distribution of this invasive species across the United States. (Source: Invasive Plant Atlas of the United States)
Up-to-the-minute distribution maps and why they are important
Reporting This Invasive Species
What is the best way and place to report the occurrence of an invasive species?
How to report an invasive species sighting to EDDMapS – Early Detection & Distribution Mapping System
EDDMapS – Report an invasive species to EDDMapS
Cooperative Extension Offices – Find your local Cooperative Extension office on this map provided by USDA
How to Identify
This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.
Plant
Orange hawkweed is an invasive perennial plant that is 11.8 to 23.6 in. (30 to 60 cm) tall and produces a milky sap.
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| Michael Shephard, USDA Forest Service, bugwood.org | Jamie Nielsen, University of Alaska Fairbanks, Cooperative Extension Service, bugwood.org |
Foliage
Leaves are mostly basal, elliptical, 2 to 8 in. (5 to 20 cm) long, 0.4 to 1.2 in. (1 to 3 cm) wide and covered with short, stiff, black hairs.
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| Michael Shephard, USDA Forest Service, bugwood.org | John Cardina, Ohio State University, bugwood.org |
Flower
Flowers are orange to red, have square-edged petals, and appear in May to June on leafless flower stalks.
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| Michael Shephard, USDA Forest Service, bugwood.org | Joseph M. DiTomaso, University of California-Davis, bugwood.org |
Fruit
Dandelion-like fruit have a white pappus attached that aids in wind dispersal.
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| Michael Shephard, USDA Forest Service, bugwood.org | Ken Chamberlain, Ohio State University, bugwood.org |
Native Species That Resemble Orange Hawkweed
All species within this genus, including natives, are designated as noxious weeds.
Hieracium gronovii, gronovius hawkweed – Images at invasive.org
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| James H. Miller & Ted Bodner, Southern Weed Science Society, bugwood.org | James H. Miller & Ted Bodner, Southern Weed Science Society, bugwood.org |
– Images at invasive.org
| bugwood.org | bugwood.org |
Additional Images for Orange Hawkweed
Orange hawkweed – Images at Invasive.org
Learning Resources for Orange Hawkweed
Additional Information, Biology, Control and Management Resources
Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state’s land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.
United States Land-Grant University System – Find your land-grant university’s College of Agriculture, Cooperative Extension Service, or other related partner on this map provided by USDA.
Weed of the Week – USDA Forest Service
Fire Effects Information System – USDA Forest Service
Hieracium aurantiacum (Orange Hawkweed) – Minnesota Wildflowers
Montana War on Weeds – Montana Department of Agriculture
Noxious Weeds – King County