Artemisia tridentata
This species is found in western Colorado, usually on open outcrops of clay-based soils called "adobe hills". Habitat types include pinyon-juniper woodland, sagebrush, saltbrush, and shrublands. Dominant plant species include "Pinus edulis" (pinyon pine), "Juniperus osteosperma" (Utah juniper), "Artemisia tridentata" (big sagebrush), "Artemisia tridentata" ssp. "wyomingensis" (Wyoming sagebrush), "Atriplex confertifolia" (saltbush), "Amelanchier utahensis" (Utah serviceberry), and "Quercus gambelii" (Gambel's oak). The thistle grows in open areas that are sparsely vegetated. It can tolerate some disturbance and may occur on roadsides.