Yellow Toadflax Linaria vulgaris Michael Shephard, USDA Forest Service, Bugwood.org A 1-3 foot tall perennial with yellow flowers and narrow leaves. Grows in a wide range of habitats, including pristine meadows. Establishes large colonies through an aggressive creeping root system.
Sulfur cinquefoil A 1-3 foot tall perennial with light yellow flowers and hairy leaves. Impacts rangeland and forests by forming large monocultures and reducing grass production. Sulfur cinquefoil is unpalatable to most wildlife and livestock. Potentilla recta Montana Statewide Noxious Weed Awareness and Education Program Archive, Montana State University, Bugwood.org
Black henbane Steve Dewey, Utah State University, Bugwood.org A 1-3 foot tall annual or biennial covered in sticky hairs with a foul odor. Grows in pastures and waste areas. Introduced as an ornamental, it is considered a narcotic and poisonous to humans and livestock. Hyoscyamus niger
St. John s wort Richard Old, XID Services, Inc., Bugwood.org A 1-3 foot tall perennial with yellow flowers. The leaves, when held up to the light, appear to have pin holes in them. Impacts pastures and rangeland and is toxic to livestock. Hypericum perforatum
Oxeye daisy A 1-3 foot tall perennial with white daisy like flowers, similar to Shasta daisy. Grows in pastures, meadows, and rangeland. Impacts include decreased forage production for cattle and livestock. Leucanthemum vulgare Mary Ellen (Mel) Harte,, Bugwood.org
Poison hemlock Ohio State Weed Lab Archive, Ohio State University, Bugwood.org A 3-8 foot tall biennial with white flowers, purple spotted stems, and ferny leaves. Can be mistaken for wild carrot. Found in pastures, crops and along ditch banks, it is highly poisonous to humans and livestock. Conium maculatum
Houndstongue Richard Old, XID Services, Inc., Bugwood.org A 1-3 foot tall biennial with reddish flowers and rough hairy leaves. Burs spread long distances by sticking to clothing and fur. Impacts rangeland and pastures and is toxic to wildlife and livestock. Cynoglossum officinale
Salt cedar Forest & Kim Starr, U.S. Geological Survey; Richard Old, XID Services, Inc., Bugwood.org A foot tall shrub with pink flowers and salt encrusted leaves. Impacts native plant communities by replacing native plants, monopolizing water reserves, and increasing fire & flood frequency. Tamarix ramosissima
The Knapweeds Spotted Centaurea biebersteinii Steve Dewey, Utah State University, Bugwood.org Cindy Roche, Bugwood.org Diffuse Centaurea diffusa Russian Acroptilion repens
Spotted Knapweed Centaurea maculosa Marisa Williams, University of Arkansas, Fayetteville, Bugwood.org A 4 foot tall perennial with branching stems that crowds out native species therefore reducing habitat for wildlife and livestock. Grows in a range of habitats from moist riparian areas to dry rocky slopes.
Diffuse knapweed Richard old, xidservices.com Centaurea diffusa A 1-4 foot branching perennial, with generally white (sometimes pink or lavender) flowers surrounded by fringed bracts and a long tipped spine. Impacts rangeland and grasslands by displacing native plant species.
Leafy Spurge A deep rooted perennial with toxic properties that is highly competitive with native vegetation. Grows in a range of habitats including pastureland, riparian areas, and dry rocky slopes. Euphorbia esula (c)Barry A. Price/The Nature Conservancy; Norman E. Rees, USDA Agricultural Research Service, Bugwood.org