Hieracium pratense L.
Yellow hawkweed is a fibrous-rooted perennial herb that can grow up to 12 inches tall. The hairy leaves are mostly basal with 1 or 2 small leaves occasionally occurring on the bristly stem. The plants contain a milky juice and have 5 to 35 clustered flower heads; the dandelion-like flowers are yellow with notched tips. Yellow hawkweed spreads via stolons, rhizomes, seeds, and root buds. Severe infestations of dense mats can choke out all other vegetation.
There are currently very few yellow hawkweed infestations in Teton County, most of which occur in Grand Teton National Park. Please note that this particular species of invasive hawkweed in difficult to identify because of the many native yellow-flowered hawkweeds in the region.
If you find this weed on your property or around Teton County, please report it immediately at 733-8419.