An erect biennial with spines on the leaves and stems. Found throughout the United States,
primarily a weed of pastures.
egg-shaped, young leaves develop as a rosette. Leaves are oblong with small spines along
the margins. Second true leaf and subsequent young leaves contain many hairs on the upper
Flowers: Clustered or solitary
at the ends of branches. Flowers are 1.5-2 inches wide, rose to reddish-purple, and
surrounded by spiny-tipped bracts.
Fruit: An achene (3-4 mm long).
Leaves: Arranged alternately on the flowering stem,
lanceolate with deeply cut margins and stiff spines on the lobes. Leaves are coarsely
hairy on the upper side and contain softer whitish hairs below. Leaf bases continue down
the flowering stem.
Stems: 2 to 5 feet tall,
branching, hairy, green or brown with age, and with the leaf margins extending down the
stem (spiny "wings").
Identifying Characteristics:Spiny-winged stems and leaves with rough hairs on the upper surface and softer
whitish hairs below. This weed is often confused with Musk
Thistle (Carduus nutans), but the leaves of mature musk thistle plants
usually lack hairs. Additionally, Canada Thistle (Cirsium
arvense) is a perennial from rhizomes, and young plants do not develop as a rosette,
unlike bull thistle.