Carduus acanthoides may exceed 2 metres (6.6 ft) in height and can form weedy monotypic stands.

[1] The plant starts from a flat, basal rosette and then bolts an erect stem with occasional toothed, wrinkled, spiny leaves.

[4] At the top of each branch of the stem is an inflorescence of one to several flower heads, each rounded, covered in spiny phyllaries, and bearing many threadlike, purple or pink disc florets.

The plant has introduced broadly across much of North America where it is sometimes considered a noxious weed or invasive species.

[4] In Michigan and Wisconsin, it does not occur in remnant, native habitats, but rather those with a history of disturbance, such as railroad right-of-ways, roadsides, and farm fields.