Scientific Name: Cirsium vulgare

Common Name: bull thistle

Other Common Names: thistle, common thistle, spear thistle

Synonyms: Carduus lanceolatus, Carduus vulgaris, Cirsium lanceolatum

Habit: Bull thistle blooms from June to October. Bull thistle rosettes remain green and continue growing throughout the winter.

Leaves: The rosette leaves ranging between 3 to 7 inches long. The upper portion of the leaf is dark green and covered with sharp prickly hairs, while the lower portion of the leaf is a lighter green and is covered with soft hairs that have a wooly feel. The stem leaves are somewhat similar to rosette leaves just smaller in size. Leaves are attached to the stem and extend down it offering a winged looked. Leaves are indented around the edge with groups of 2 or 3 spine-tipped lobes interspersed with non-lobed portions.

Identifying Characteristics: Reproduction is performed only through the seeds. Bull thistle plants can produce approximately 7000 seeds.

Flower Seed Head: The flowers are located at the end of stems covered in spiny hairs. The outer rim of the flower is green and spiny itself, and contains many disk shaped flowers that are reddish-purple.

Seed Fruit: The seeds are straw colored with a black streak approximately 1/6 inch long. One end of the seed contains many brown hairs.

Where Found: The bull thistle is now established on every continent except the frozen tundra of Antarctica. It grows as a weed in pastures, roadsides, and fields that have been abandoned. It prefers disturbed areas with rich and moist soils.

  • Life cycle: biennial

  • Milky sap: Not Present

  • Plant type: Herb

  • Thorns: Present

  • Plant family: Asteraceae

  • Leaf arrangement: opposite; rosette; alternate

  • Leaf shape: oval

  • Ochrea: Not Present

  • Leaf margin: serrated; entire; lobed

  • Stem hairs: has hairs

  • Flower color: purple; red

  • Growth habit: upright and nonwoody

  • Stem: round or oval

  • Leaf structure: simple

  • Leaf hairs: has hairs

  • Flower diameter: half dollar; nickle; quarter; larger

  • Flower symmetry: radial symetery

  • Root structure: taproot

  • Leaf stalk: none