Photo Credit: Nicole Kimmel, Alberta Agriculture & Forestry
Plumeless thistle is native to southern Europe and western Asia. It was introduced to North America in the 1870s in ballast water of ships.
Infestations of plumeless thistle can reduce the productivity of pastures because it suppresses the growth of available vegetation for livestock. This plant is generally unpalatable to grazing animals. It thrives in a variety of conditions and can out-compete native species.
The flowers are purple in color and the flower heads are 30-35 mm wide. Its bracts have a short spine at their tip.
The leaves of plumeless thistle are deeply lobed, dark green on the top side, lighter green on the underside, and have spines along the edges.
This thistle can grow up to 2 m tall and is covered in spines.
Learn more about this species:
See Fact Sheets - Alberta Invasive Species Council