- Carduus acanthoides is an annual or biennial herbaceous plant that grows to 5 ft. (1.5 m) tall.
- This thistle may exceed two meters in height and can form weedy monotypic stands. The stem and foliage are spiny and sometimes woolly.
- Flowering occurs from May to August. The flower heads are reddish-purple in color and up to 1 in. (2.5 cm) in diameter. Flower stems are branched with spiny wings extending to the flower heads.
- Seeds are oblong, striate, and slightly curved.
- Ecological Threat
- Carduus acanthoides infests open, disturbed areas such as pastures, roadsides, and railroad right-of-ways. It can form thick stands that reduce the forage potential of pastures and suppress the growth of desirable vegetation.