Bull thistle is a herbaceous biennial. Flowering plants can range from 1-7' tall. Stems are spiny winged.
Leaves: First year basal rosette leaves can be 20" long. Stem leaves are alternate and coarsely lobed. Lobe tips have stout spines. Leaves are spiny on top and have white woolly hair below.
Flowers: Flower heads are brush like and are pink to purple. There can be on or a cluster of flower heads at the end of the stem. Flower heads are .5" to 2" across, and are on winged stems; bracts with spiny tips. Blooms in May-August.
Fruits & Seeds: Seeds have a tuft of feathery bristles and are dispersed in the wind.
Roots: Has a taproot system.
- Bull thistle will invade prairies, fields, pastures, roadsides, and ditches.