Orange hawkweed
Hieracium aurantiacum
Keys to Identification
Orange hawkweed is a perennial member of the sunflower family (Asteraceae)- It likes moist grassy areas and can be found along creeks, in meadows, and along rights-of-way
- Reproduces by runners and by seed
- Each bright orange flower is between 1/2 to 1 inch wide. They are grouped at the top of a slender stem and tend to close up when it is shady, making the plants difficult to see
- Hairy leaves are found at the base of the plant
- Orange hawkweed is found in only a few places in Colorado and is on the A List, requiring eradication
This information courtesy of the Colorado Natural Areas Program
Family: Asteraceae (Sunflower)
Other Names: Devil's paintbrush
USDA Code: HIAU
Legal Status: Colorado Noxious Weed List A
New in Colorado – Notify your county weed supervisor if you find this plant!
Identification
Lifecycle: Perennial
Growth form: Forb
Flower: Orange in groups of up to 13 at the end of stem. June-July.
Seeds/Fruit: With papus
Leaves: Basal. Dark green hairy.
Stems: Fine, leafless. 1-2 ft tall. With stiff hairs
Roots: Fibrous spreading with stolons at nodes
Seedling: Seedling leaves have bristly hairs
Similar Species
Exotics: Yellow hawkweed
Natives: Native hawkweeds and false dandelion
Impacts
Agricultural: Infests hay fields, animals will not feed
Ecological: Forms mats that prevent other plants from growing
Habitat and Distribution
General requirements: Likes shady areas. Can be found in grassy areas. Moist pastures, stream banks
Distribution: Found in a number of counties in Colorado in small populations. Native to Europe, also found throughout northern US
Biology/Ecology
Life cycle: Perennial plants form rosettes in spring and early summer, spread primarily through stolons. Plants flower in June-July
Mode of reproduction: Seed, stolons, rhizomes
Seed production: Each stem may produce thousands of seeds
Seed bank: Not known
Dispersal: Wildflower seed mixes, wind, water and possibly animals
Integrated Management Summary
This species is not yet widespread in Colorado, and should be a priority for immediate eradication if found. As with other plants which reproduce solely by seed, integrated management efforts of myrtle spurge must include the elimination of seed production and the depletion of the seed bank. Combine herbicide or mechanical removal of rosettes with removal of flowering parts from any plants that have bolted.
References
Callihan, R.H., L.M. Wilson, J.P. McCaffery, T.W. Miller, 1997. Hawkweeds. Pacific Northwest Extension Publication 499. Cooperatively published by the University of Idaho Cooperative Extension, Oregon State Cooperative Extension Service, Washington State Cooperative Extension and the U.S. Department of Agriculture.
Hoffman, R. & K. Kearns, Eds.. 1997. Wisconsin Manual of Control Recommendations for Ecologically Invasive Plants. Wisconsin Dept. Natural Resources. Madison, Wisconsin.. 102pp.
Whitson, T.D. (Ed.) et al.. 1996. Weeds of the West. Western Society of Weed Science in cooperation with Cooperative Extension Services, University of Wyoming. Laramie, Wyoming. 630pp.
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