Plumeless Thistle

Common Name: Plumeless Thistle Scientific Name: Carduus acanthoides Habitat: farmland, roadsides, disturbed areas, grassland and dry grassland Provincial Designation: Prohibited Noxious Prohibited Noxious weeds are plant species that are designated as "prohibited noxious" in the Alberta weed regulation. Prohibited noxious weeds must be destroyed, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable.

Origin

Plumeless thistle is native to Southern Europe and Western Asia. It was introduced to North America in the 1870s in ballast water of ships. 

Legislated Because

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.

Description

The flowers are purple in colour 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