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Colorado Parks and Wildlife offices will be closed on December 24, December 25, December 26 and January 1.
Yellow Starthistle
The yellow starthistle is an invasive, noxious weed that causes damage to Colorado's ecosystem.
About This Species
Yellow starthistle is not native to Colorado. It is classified as a "List A" species in the Colorado Noxious Weed Act, designating it for statewide eradication.
Photos courtesy of Minnesota Department of Agriculture
More Information:
Physical Characteristics
Yellow starthistle is an annual or winter annual forb that grows 2-3 feet tall and has a vigorous taproot. The flowers are yellow, located singly on the ends of branches. Below the flowers are sharp, stiff thorns about ¾ inch in length. The flower emerges as a rosette with deeply lobed leaves in the early spring. The upper leaf edges are smooth and sharply pointed. The stems are branching, winged and covered with cottony hairs.
Habitat
Yellow starthistle prefers rangeland, pastures, roadsides, wastelands, and lower elevations.